scripted/pyApiMeshShape.py

#-
# ===========================================================================
# Copyright 2015 Autodesk, Inc.  All rights reserved.
#
# Use of this software is subject to the terms of the Autodesk license
# agreement provided at the time of installation or download, or which
# otherwise accompanies this software in either electronic or hard copy form.
# ===========================================================================
#+

import sys, math, ctypes, collections
import maya.api.OpenMaya as om
import maya.api.OpenMayaUI as omui
import maya.api.OpenMayaRender as omr

def maya_useNewAPI():
    """
    The presence of this function tells Maya that the plugin produces, and
    expects to be passed, objects created using the Maya Python API 2.0.
    """
    pass

## helper function
def useSelectHighlight(selectedList, path):
    
    displayStatus = omr.MGeometryUtilities.displayStatus(path)
    if displayStatus == omr.MGeometryUtilities.kHilite or displayStatus == omr.MGeometryUtilities.kActiveComponent:
        return True
    
    pathCopy = om.MDagPath(path)

    while pathCopy.length() > 0:
        if selectedList.hasItem(pathCopy):
            return True
        pathCopy.pop()

    return False

def floatApproxEqual(left, right):
    return abs(left - right) < 0.0001

################################################################################
##
## This class holds the underlying geometry for the shape or data.
## This is where geometry specific data and methods should go.
##
################################################################################
class apiMeshGeomUV:
    def __init__(self, other=None):
        if other:
            self.copy(other)
        else:
            self.reset()

    def uvId(self, fvi):
        return self.faceVertexIndex[fvi]

    def getUV(self, uvId):
        return [ self.ucoord[uvId], self.vcoord[uvId] ]

    def u(self, uvId):
        return self.ucoord[uvId]

    def v(self, uvId):
        return self.vcoord[uvId]

    def uvcount(self):
        return len(self.ucoord)

    def append_uv(self, u, v):
        self.ucoord.append( u ) 
        self.vcoord.append( v ) 

    def reset(self):
        self.ucoord = om.MFloatArray()
        self.vcoord = om.MFloatArray()
        self.faceVertexIndex = om.MIntArray()

    def copy(self, other):
        self.ucoord = om.MFloatArray(other.ucoord)
        self.vcoord = om.MFloatArray(other.vcoord)
        self.faceVertexIndex = om.MIntArray(other.faceVertexIndex)

class apiMeshGeom:
    def __init__(self):
        self.vertices = om.MPointArray()
        self.face_counts = om.MIntArray()
        self.face_connects = om.MIntArray()
        self.normals = om.MVectorArray()
        self.uvcoords = apiMeshGeomUV()
        self.faceCount = 0

    def copy(self, other):
        self.vertices = om.MPointArray(other.vertices)
        self.face_counts = om.MIntArray(other.face_counts)
        self.face_connects = om.MIntArray(other.face_connects)
        self.normals = om.MVectorArray(other.normals)
        self.uvcoords = apiMeshGeomUV(other.uvcoords)
        self.faceCount = other.faceCount

################################################################################
##
## Provides a data type for some arbitrary user geometry.
## 
## A users geometry class can exist in the DAG by creating an
## MPxSurfaceShape (and UI) class for it and can also be passed through
## DG connections by creating an MPxGeometryData class for it.
## 
## MPxGeometryData is the same as MPxData except it provides 
## additional methods to modify the geometry data via an iterator.
##
################################################################################
## Ascii file IO defines
##
kDblQteChar     = "\""
kSpaceChar      = " "
kWrapString     = "\n\t\t"
kVertexKeyword  = "v"
kNormalKeyword  = "vn"
kTextureKeyword = "vt"
kFaceKeyword    = "face"
kUVKeyword      = "uv" 

class apiMeshGeomIterator(om.MPxGeometryIterator):
    def __init__(self, userGeometry, components):
        om.MPxGeometryIterator.__init__(self, userGeometry, components)
        self.geometry = userGeometry
        self.reset()

    def reset(self):
        ## Resets the iterator to the start of the components so that another
        ## pass over them may be made.
        ##
        om.MPxGeometryIterator.reset(self)
        self.currentPoint = 0
        if self.geometry:
            maxVertex = len(self.geometry.vertices)
            self.maxPoints = maxVertex

    def point(self):
        ## Returns the point for the current element in the iteration.
        ## This is used by the transform tools for positioning the
        ## manipulator in component mode. It is also used by deformers.  
        ##
        pnt = om.MPoint()
        if self.geometry:
            pnt = self.geometry.vertices[ self.index() ]
        return pnt

    def setPoint(self, pnt):
        ## Set the point for the current element in the iteration.
        ## This is used by deformers.    
        ##
        if self.geometry:
            self.geometry.vertices[ self.index() ] = pnt

    def iteratorCount(self):
        ## Return the number of vertices in the iteration.
        ## This is used by deformers such as smooth skinning
        ##
        if self.geometry:
            return len(self.geometry.vertices)
        return 0

    def hasPoints(self):
        ## Returns true since the shape data has points.
        ##
        return True

class apiMeshData(om.MPxGeometryData):
    typeName = "apiMeshData"
    id = om.MTypeId(0x80777)

    @staticmethod
    def creator():
        return apiMeshData()

    def __init__(self):
        om.MPxGeometryData.__init__(self)
        self.fGeometry = apiMeshGeom()

    def __del__(self):
        self.fGeometry = None

    def readASCII(self, argList, idx):
        idx = self.readVerticesASCII(argList, idx)
        idx = self.readNormalsASCII(argList, idx)
        idx = self.readFacesASCII(argList, idx)
        idx = self.readUVASCII(argList, idx)
        return idx

    def readBinary(self, inputData, length):
        ## not implemented
        return 0

    def writeASCII(self):
        data  = self.writeVerticesASCII()
        data += self.writeNormalsASCII()
        data += self.writeFacesASCII()
        data += writeUVASCII()
        return data

    def writeBinary(self):
        ## not implemented
        return bytearray()

    def copy(self, src):
        self.fGeometry.copy(src.fGeometry)
    
    def typeId(self):
        return apiMeshData.id

    def name(self):
        return apiMeshData.typeName

    ##################################################################
    ##
    ## Overrides from MPxGeometryData
    ##
    ##################################################################

    def iterator(self, componentList, component, useComponents, world=None):
        if useComponents:
            return apiMeshGeomIterator(self.fGeometry, componentList)

        return apiMeshGeomIterator(self.fGeometry, component)
    
    ##################################################################
    ##
    ## Helper methods
    ##
    ##################################################################

    def readVerticesASCII(self, argList, idx):
        geomStr = ""
        try:
            geomStr = argList.asString(idx)
        except:
            geomStr = ""
            pass

        if geomStr == kVertexKeyword:
            idx = argList.lastArgUsed()+1
            vertexCount = argList.asInt(idx)
            idx = argList.lastArgUsed()+1
            for i in xrange(vertexCount):
                vertex = argList.asPoint(idx)
                idx = argList.lastArgUsed()+1
                self.fGeometry.vertices.append(vertex)

        return idx

    def readNormalsASCII(self, argList, idx):
        geomStr = ""
        try:
            geomStr = argList.asString(idx)
        except:
            geomStr = ""
            pass

        if geomStr == kNormalKeyword:
            idx = argList.lastArgUsed()+1
            normalCount = argList.asInt(idx)
            idx = argList.lastArgUsed()+1
            for i in xrange(normalCount):
                normal = argList.asVector(idx)
                idx = argList.lastArgUsed()+1
                self.fGeometry.normals.append(normal)

        return idx

    def readFacesASCII(self, argList, idx):
        geomStr = ""
        try:
            geomStr = argList.asString(idx)
        except:
            geomStr = ""
            pass

        while geomStr == kFaceKeyword:
            idx = argList.lastArgUsed()+1
            faceCount = argList.asInt(idx)
            idx = argList.lastArgUsed()+1
            self.fGeometry.face_counts.append(faceCount)
            for i in xrange(faceCount):
                vid = argList.asInt(idx)
                idx = argList.lastArgUsed()+1
                self.fGeometry.face_connects.append(vid)

            try:
                geomStr = argList.asString(idx)
            except:
                geomStr = ""
                pass

        self.fGeometry.faceCount = len(self.fGeometry.face_counts)
        return idx

    def readUVASCII(self, argList, idx):
        self.fGeometry.uvcoords.reset()

        geomStr = ""
        try:
            geomStr = argList.asString(idx)
        except:
            geomStr = ""
            pass

        if geomStr == kUVKeyword:
            idx = argList.lastArgUsed()+1
            uvCount = argList.asInt(idx)
            idx = argList.lastArgUsed()+1
            faceVertexListCount = argList.asInt(idx)
            idx = argList.lastArgUsed()+1
            for i in xrange(uvCount):
                u = argList.asDouble(idx)
                idx = argList.lastArgUsed()+1
                v = argList.asDouble(idx)
                idx = argList.lastArgUsed()+1
                self.fGeometry.uvcoords.append_uv(u, v)

            for i in xrange(faceVertexListCount):
                fvi = argList.asInt(idx)
                idx = argList.lastArgUsed()+1
                self.fGeometry.uvcoords.faceVertexIndex.append( fvi )

        return idx

    def writeVerticesASCII(self):
        vertexCount = len(self.fGeometry.vertices)

        data  = "\n"
        data += kWrapString
        data += kDblQteChar + kVertexKeyword + kDblQteChar + kSpaceChar + str(vertexCount)

        for i in xrange(vertexCount):
            vertex = self.fGeometry.vertices[i]

            data += kWrapString
            data += str(vertex[0]) + kSpaceChar + str(vertex[1]) + kSpaceChar + str(vertex[2])

        return data

    def writeNormalsASCII(self):
        normalCount = len(self.fGeometry.normals)

        data  = "\n"
        data += kWrapString
        data += kDblQteChar + kNormalKeyword + kDblQteChar + kSpaceChar + str(normalCount)

        for i in xrange(normalCount):
            normal = self.fGeometry.normals[i]

            data += kWrapString
            data += str(normal[0]) + kSpaceChar + str(normal[1]) + kSpaceChar + str(normal[2])

        return data

    def writeFacesASCII(self):
        numFaces = len(self.fGeometry.face_counts)

        data = ""
        vid = 0

        for i in xrange(numFaces):
            faceVertexCount = self.fGeometry.face_counts[i]

            data += "\n"
            data += kWrapString
            data += kDblQteChar + kFaceKeyword + kDblQteChar + kSpaceChar + str(faceVertexCount)

            data += kWrapString

            for v in xrange(faceVertexCount):
                value = self.fGeometry.face_connects[vid]

                data += str(value) + kSpaceChar
                vid += 1

        return data

    def writeUVASCII(self):
        uvCount = self.fGeometry.uvcoords.uvcount()
        faceVertexCount = len(self.fGeometry.uvcoords.faceVertexIndex)

        data = ""

        if uvCount > 0:
            data  = "\n"
            data += kWrapString
            data += kDblQteChar + kUVKeyword + kDblQteChar + kSpaceChar + str(uvCount) + kSpaceChar + str(faceVertexCount)

            for i in xrange(uvCount):
                uv = self.fGeometry.uvcoords.getUV(i)

                data += kWrapString
                data += uv[0] + kSpaceChar + uv[1] + kSpaceChar

            for i in xrange(faceVertexCount):
                value = self.fGeometry.uvcoords.faceVertexIndex[i]

                data += kWrapString
                data += value + kSpaceChar

        return data


################################################################################
##
## apiMeshShape
##
## Implements a new type of shape node in maya called apiMesh.
##
## INPUTS
##     inputSurface    - input apiMeshData
##     outputSurface   - output apiMeshData
##     worldSurface    - array of world space apiMeshData, each element
##                       represents an istance of the shape
## OUTPUTS
##     mControlPoints  - inherited control vertices for the mesh. These values
##                       are tweaks (offsets) that will be applied to the
##                       vertices of the input shape.
##     bboxCorner1     - bounding box upper left corner
##     bboxCorner2     - bounding box lower right corner
##
################################################################################
class apiMesh(om.MPxSurfaceShape):
    id = om.MTypeId(0x80099)

    ##########################################################
    ##
    ## Attributes
    ##
    ##########################################################
    inputSurface = None
    outputSurface = None
    worldSurface = None

    useWeightedTransformUsingFunction = None
    useWeightedTweakUsingFunction = None

    ## used to support tweaking of points, the inputSurface attribute data is
    ## transferred into the cached surface when it is dirty. The control points
    ## tweaks are added into it there.
    ##
    cachedSurface = None

    bboxCorner1 = None
    bboxCorner2 = None

    @staticmethod
    def creator():
        return apiMesh()

    @staticmethod
    def initialize():
        typedAttr = om.MFnTypedAttribute()
        numericAttr = om.MFnNumericAttribute()

        ## ----------------------- INPUTS --------------------------
        apiMesh.inputSurface = typedAttr.create( "inputSurface", "is", apiMeshData.id, om.MObject.kNullObj )
        typedAttr.storable = False
        om.MPxNode.addAttribute( apiMesh.inputSurface )

        apiMesh.useWeightedTransformUsingFunction = numericAttr.create( "useWeightedTransformUsingFunction", "utru", om.MFnNumericData.kBoolean, True )
        numericAttr.keyable = True
        om.MPxNode.addAttribute( apiMesh.useWeightedTransformUsingFunction )

        apiMesh.useWeightedTweakUsingFunction = numericAttr.create( "useWeightedTweakUsingFunction", "utwu", om.MFnNumericData.kBoolean, True )
        numericAttr.keyable = True
        om.MPxNode.addAttribute( apiMesh.useWeightedTweakUsingFunction )

        ## ----------------------- OUTPUTS -------------------------

        ## bbox attributes
        ##
        apiMesh.bboxCorner1 = numericAttr.create( "bboxCorner1", "bb1", om.MFnNumericData.k3Double, 0 )
        numericAttr.array = False
        numericAttr.usesArrayDataBuilder = False
        numericAttr.hidden = False
        numericAttr.keyable = False
        om.MPxNode.addAttribute( apiMesh.bboxCorner1 )

        apiMesh.bboxCorner2 = numericAttr.create( "bboxCorner2", "bb2", om.MFnNumericData.k3Double, 0 )
        numericAttr.array = False
        numericAttr.usesArrayDataBuilder = False
        numericAttr.hidden = False
        numericAttr.keyable = False
        om.MPxNode.addAttribute( apiMesh.bboxCorner2 )

        ## local/world output surface attributes
        ##
        apiMesh.outputSurface = typedAttr.create( "outputSurface", "os", apiMeshData.id, om.MObject.kNullObj )
        typedAttr.writable = False
        om.MPxNode.addAttribute( apiMesh.outputSurface )

        apiMesh.worldSurface = typedAttr.create( "worldSurface", "ws", apiMeshData.id, om.MObject.kNullObj )
        typedAttr.cached = False
        typedAttr.writable = False
        typedAttr.array = True
        typedAttr.usesArrayDataBuilder = True
        typedAttr.disconnectBehavior = om.MFnAttribute.kDelete
        typedAttr.worldSpace = True
        om.MPxNode.addAttribute( apiMesh.worldSurface )

        ## Cached surface used for file IO
        ##
        apiMesh.cachedSurface = typedAttr.create( "cachedSurface", "cs", apiMeshData.id, om.MObject.kNullObj )
        typedAttr.readable = True
        typedAttr.writable = True
        typedAttr.storable = True
        om.MPxNode.addAttribute( apiMesh.cachedSurface )

        ## ---------- Specify what inputs affect the outputs ----------
        ##
        om.MPxNode.attributeAffects( apiMesh.inputSurface, apiMesh.outputSurface )
        om.MPxNode.attributeAffects( apiMesh.inputSurface, apiMesh.worldSurface )
        om.MPxNode.attributeAffects( apiMesh.outputSurface, apiMesh.worldSurface )
        om.MPxNode.attributeAffects( apiMesh.inputSurface, apiMesh.bboxCorner1 )
        om.MPxNode.attributeAffects( apiMesh.inputSurface, apiMesh.bboxCorner2 )
        om.MPxNode.attributeAffects( apiMesh.cachedSurface, apiMesh.outputSurface )
        om.MPxNode.attributeAffects( apiMesh.cachedSurface, apiMesh.worldSurface )

        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlPoints, apiMesh.outputSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueX, apiMesh.outputSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueY, apiMesh.outputSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueZ, apiMesh.outputSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlPoints, apiMesh.cachedSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueX, apiMesh.cachedSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueY, apiMesh.cachedSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueZ, apiMesh.cachedSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlPoints, apiMesh.worldSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueX, apiMesh.worldSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueY, apiMesh.worldSurface )
        om.MPxNode.attributeAffects( om.MPxSurfaceShape.mControlValueZ, apiMesh.worldSurface )

    def __init__(self):
        om.MPxSurfaceShape.__init__(self)

    ##########################################################
    ##
    ## Overrides
    ##
    ##########################################################

    ## From MPxNode
    ##
    def postConstructor(self):
        ##
        ## Description
        ##
        ##    When instances of this node are created internally, the MObject associated
        ##    with the instance is not created until after the constructor of this class
        ##    is called. This means that no member functions of MPxSurfaceShape can
        ##    be called in the constructor.
        ##    The postConstructor solves this problem. Maya will call this function
        ##    after the internal object has been created.
        ##    As a general rule do all of your initialization in the postConstructor.
        ##

        ## This call allows the shape to have shading groups assigned
        ##
        self.isRenderable = True

        ## Is there input history to this node
        ##
        self.fHasHistoryOnCreate = False

        ## Is the shape dirty? Used by VP2.0 sub-scene evaluator
        ##
        self.fShapeDirty = True
        self.fMaterialDirty = True

    def compute(self, plug, datablock):
        ##
        ## Description
        ##
        ##    When input attributes are dirty this method will be called to
        ##    recompute the output attributes.
        ##
        ## Arguments
        ##
        ##    plug      - the attribute that triggered the compute
        ##    datablock - the nodes data
        ##

        if plug == apiMesh.outputSurface:
            return self.computeOutputSurface( plug, datablock )

        elif plug == apiMesh.cachedSurface:
            return self.computeOutputSurface( plug, datablock )

        elif plug == apiMesh.worldSurface:
            return self.computeWorldSurface( plug, datablock )

        else:
            return None

    def preEvaluation(self, context, evaluationNode):
        ##
        ## Description
        ##
        ##    Pre evaluate will mark the shape as dirty
        ##    PreEvaluate will be called before each evaluation of this node 
        ##
        ## Arguments
        ##
        ##    context        - Evaluation context in which the compute happen
        ##    evaluationNode - contains information about the dirtyness of plugs
        ##
        if context.isNormal():
            if evaluationNode.dirtyPlugExists(apiMesh.inputSurface) or evaluationNode.dirtyPlugExists(apiMesh.mControlPoints):
                self.setShapeDirty()

    def postEvaluation(self, context, evaluationNode, evalType):
        ##
        ## Description
        ##
        ##    Post evaluate will signal viewport dirty so that renderer can pick it up
        ##    PostEvaluate will be called before each evaluation of this node 
        ##
        ## Arguments
        ##
        ##    context        - Evaluation context in which the compute happen
        ##    evaluationNode - contains information about the dirtyness of plugs
        ##    evalType       - type of evaluation that was performed
        ##
        if context.isNormal():
            if evaluationNode.dirtyPlugExists(apiMesh.inputSurface) or evaluationNode.dirtyPlugExists(apiMesh.mControlPoints):
                self.notifyViewport()

    def setDependentsDirty(self, plug, plugArray):
        ##
        ## Description
        ##
        ##  Horribly abuse the purpose of this method to notify the Viewport 2.0
        ##  renderer that something about this shape has changed and that it should
        ##  be retranslated.
        ##

        ## if the dirty attribute is the output mesh then we need to signal the
        ## the renderer that it needs to update the object

        if plug == apiMesh.inputSurface or plug == om.MPxSurfaceShape.mControlPoints or plug == om.MPxSurfaceShape.mControlValueX or plug == om.MPxSurfaceShape.mControlValueY or plug == om.MPxSurfaceShape.mControlValueZ:
            self.signalDirtyToViewport()

    def getInternalValue(self, plug, handle):
        ##
        ## Description
        ##
        ##    Handle internal attributes.
        ##
        ##    Attributes that require special storage, bounds checking,
        ##    or other non-standard behavior can be marked as "Internal" by
        ##    using the "MFnAttribute.setInternal" method.
        ##
        ##    The get/setInternalValue methods will get called for internal
        ##    attributes whenever the attribute values are stored or retrieved
        ##    using getAttr/setAttr or MPlug getValue/setValue.
        ##
        ##    The inherited attribute mControlPoints is internal and we want
        ##    its values to get stored only if there is input history. Otherwise
        ##    any changes to the vertices are stored in the cachedMesh and outputMesh
        ##    directly.
        ##
        ##    If values are retrieved then we want the controlPoints value
        ##    returned if there is history, this will be the offset or tweak.
        ##    In the case of no history, the vertex position of the cached mesh
        ##    is returned.
        ##
        isOk = True

        if plug == om.MPxSurfaceShape.mControlPoints or plug == om.MPxSurfaceShape.mControlValueX or plug == om.MPxSurfaceShape.mControlValueY or plug == om.MPxSurfaceShape.mControlValueZ:
            ## If there is input history then the control point value is
            ## directly returned. This is the tweak or offset that
            ## was applied to the vertex.
            ##
            ## If there is no input history then return the actual vertex
            ## position and ignore the controlPoints attribute.
            ##
            if self.hasHistory():
                return om.MPxNode.getInternalValue(self, plug, handle)

            else:
                if plug == om.MPxSurfaceShape.mControlPoints and not plug.isArray():
                    index = plug.logicalIndex()
                    pnt = self.getPointValue(index)
                    handle.set3Double( pnt[0], pnt[1], pnt[2] )

                elif plug == om.MPxSurfaceShape.mControlValueX:
                    parentPlug = plug.parent()
                    index = parentPlug.logicalIndex()
                    val = self.getChannelValue( index, 0 )
                    handle.setDouble( val )

                elif plug == om.MPxSurfaceShape.mControlValueY:
                    parentPlug = plug.parent()
                    index = parentPlug.logicalIndex()
                    val = self.getChannelValue( index, 1 )
                    handle.setDouble( val )

                elif plug == om.MPxSurfaceShape.mControlValueZ:
                    parentPlug = plug.parent()
                    index = parentPlug.logicalIndex()
                    val = self.getChannelValue( index, 2 )
                    handle.setDouble( val )

        ## This inherited attribute is used to specify whether or
        ## not this shape has history. During a file read, the shape
        ## is created before any input history can get connected.
        ## This attribute, also called "tweaks", provides a way to
        ## for the shape to determine if there is input history
        ## during file reads.
        ##
        elif plug == om.MPxSurfaceShape.mHasHistoryOnCreate:
            handle.setBool( self.fHasHistoryOnCreate )

        else:
            isOk = om.MPxSurfaceShape.getInternalValue(self, plug, handle)

        return isOk

    def setInternalValue(self, plug, handle):
        ##
        ## Description
        ##
        ##    Handle internal attributes.
        ##
        ##    Attributes that require special storage, bounds checking,
        ##    or other non-standard behavior can be marked as "Internal" by
        ##    using the "MFnAttribute.setInternal" method.
        ##
        ##    The get/setInternalValue methods will get called for internal
        ##    attributes whenever the attribute values are stored or retrieved
        ##    using getAttr/setAttr or MPlug getValue/setValue.
        ##
        ##    The inherited attribute mControlPoints is internal and we want
        ##    its values to get stored only if there is input history. Otherwise
        ##    any changes to the vertices are stored in the cachedMesh and outputMesh
        ##    directly.
        ##
        ##    If values are retrieved then we want the controlPoints value
        ##    returned if there is history, this will be the offset or tweak.
        ##    In the case of no history, the vertex position of the cached mesh
        ##    is returned.
        ##
        isOk = True

        if plug == om.MPxSurfaceShape.mControlPoints or plug == om.MPxSurfaceShape.mControlValueX or plug == om.MPxSurfaceShape.mControlValueY or plug == om.MPxSurfaceShape.mControlValueZ:
            ## If there is input history then set the control points value
            ## using the normal mechanism. In this case we are setting
            ## the tweak or offset that will get applied to the input
            ## history.
            ##
            ## If there is no input history then ignore the controlPoints
            ## attribute and set the vertex position directly in the
            ## cachedMesh.
            ##
            if self.hasHistory():
                self.verticesUpdated()
                return om.MPxNode.setInternalValue(self, plug, handle)

            else:
                if plug == om.MPxSurfaceShape.mControlPoints and not plug.isArray():
                    index = plug.logicalIndex()
                    self.setPointValue( index, handle.asDouble3() )

                elif plug == om.MPxSurfaceShape.mControlValueX:
                    parentPlug = plug.parent()
                    index = parentPlug.logicalIndex()
                    self.setChannelValue( index, 0, handle.asDouble() )

                elif plug == om.MPxSurfaceShape.mControlValueY:
                    parentPlug = plug.parent()
                    index = parentPlug.logicalIndex()
                    self.setChannelValue( index, 1, handle.asDouble() )

                elif plug == om.MPxSurfaceShape.mControlValueZ:
                    parentPlug = plug.parent()
                    index = parentPlug.logicalIndex()
                    self.setChannelValue( index, 2, handle.asDouble() )

        ## This inherited attribute is used to specify whether or
        ## not this shape has history. During a file read, the shape
        ## is created before any input history can get connected.
        ## This attribute, also called "tweaks", provides a way to
        ## for the shape to determine if there is input history
        ## during file reads.
        ##
        elif plug == om.MPxSurfaceShape.mHasHistoryOnCreate:
            self.fHasHistoryOnCreate = handle.asBool()

        else:
            isOk = om.MPxSurfaceShape.setInternalValue(self, plug, handle)

        return isOk

    def connectionMade(self, plug, otherPlug, asSrc):
        ##
        ## Description
        ##
        ##    Whenever a connection is made to this node, this method
        ##    will get called.
        ##

        if plug == apiMesh.inputSurface:
            thisObj = self.thisMObject()
            historyPlug = om.MPlug( thisObj, om.MPxSurfaceShape.mHasHistoryOnCreate )
            historyPlug.setBool( True )
        else:
            thisObj = self.thisMObject()
            dgNode = om.MFnDependencyNode( thisObj )
            instObjGroups = dgNode.findPlug("instObjGroups", True)
            if plug == instObjGroups:
                self.setMaterialDirty(True)

        return om.MPxNode.connectionMade(self, plug, otherPlug, asSrc )

    def connectionBroken(self, plug, otherPlug, asSrc):
        ##
        ## Description
        ##
        ##    Whenever a connection to this node is broken, this method
        ##    will get called.
        ##

        if plug == apiMesh.inputSurface:
            thisObj = self.thisMObject()
            historyPlug = om.MPlug( thisObj, om.MPxSurfaceShape.mHasHistoryOnCreate )
            historyPlug.setBool( False )
        else:
            thisObj = self.thisMObject()
            dgNode = om.MFnDependencyNode( thisObj )
            instObjGroups = dgNode.findPlug("instObjGroups", True)
            if plug == instObjGroups:
                self.setMaterialDirty(True)

        return om.MPxNode.connectionBroken(self, plug, otherPlug, asSrc )

    def shouldSave(self, plug):
        ##
        ## Description
        ##
        ##    During file save this method is called to determine which
        ##    attributes of this node should get written. The default behavior
        ##    is to only save attributes whose values differ from the default.
        ##

        result = True

        if plug == om.MPxSurfaceShape.mControlPoints or plug == om.MPxSurfaceShape.mControlValueX or plug == om.MPxSurfaceShape.mControlValueY or plug == om.MPxSurfaceShape.mControlValueZ:
            if self.hasHistory():
                ## Calling this will only write tweaks if they are
                ## different than the default value.
                ##
                result = om.MPxNode.shouldSave(self, plug)

            else:
                result = False

        elif plug == apiMesh.cachedSurface:
            if self.hasHistory():
                result = False

            else:
                data = plug.asMObject()
                result = not data.isNull()

        else:
            result = om.MPxNode.shouldSave(self, plug)

        return result

    ## Attribute to component (components)
    ##
    def componentToPlugs(self, component, list):
        ##
        ## Description
        ##
        ##    Converts the given component values into a selection list of plugs.
        ##    This method is used to map components to attributes.
        ##
        ## Arguments
        ##
        ##    component - the component to be translated to a plug/attribute
        ##    list      - a list of plugs representing the passed in component
        ##

        if component.hasFn(om.MFn.kSingleIndexedComponent):
            fnVtxComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(component) )
            thisNode = self.thisMObject()
            plug = om.MPlug( thisNode, om.MPxSurfaceShape.mControlPoints )
            ## If this node is connected to a tweak node, reset the
            ## plug to point at the tweak node.
            ##
            self.convertToTweakNodePlug(plug)

            for i in xrange(fnVtxComp.elementCount):
                plug.selectAncestorLogicalIndex(fnVtxComp.element(i), plug.attribute())
                list.add(plug)

    def matchComponent(self, item, spec, list):
        ##
        ## Description:
        ##
        ##    Component/attribute matching method.
        ##    This method validates component names and indices which are
        ##    specified as a string and adds the corresponding component
        ##    to the passed in selection list.
        ##
        ##    For instance, select commands such as "select shape1.vtx[0:7]"
        ##    are validated with this method and the corresponding component
        ##    is added to the selection list.
        ##
        ## Arguments
        ##
        ##    item - DAG selection item for the object being matched
        ##    spec - attribute specification object
        ##    list - list to add components to
        ##
        ## Returns
        ##
        ##    the result of the match
        ##

        result = om.MPxSurfaceShape.kMatchOk
        attrSpec = spec[0]
        dim = attrSpec.dimensions

        ## Look for attributes specifications of the form :
        ##     vtx[ index ]
        ##     vtx[ lower:upper ]
        ##
        if len(spec) == 1 and dim > 0 and attrSpec.name == "vtx":
            numVertices = len(self.meshGeom().vertices)
            attrIndex = attrSpec[0]

            upper = 0
            lower = 0
            if attrIndex.hasLowerBound():
                lower = attrIndex.getLower()
            if attrIndex.hasUpperBound():
                upper = attrIndex.getUpper()

            ## Check the attribute index xrange is valid
            ##
            if lower > upper or upper >= numVertices:
                result = om.MPxSurfaceShape.kMatchInvalidAttributeRange

            else:
                path = item.getDagPath(0)
                fnVtxComp = om.MFnSingleIndexedComponent()
                vtxComp = fnVtxComp.create( om.MFn.kMeshVertComponent )

                for i in xrange(lower, upper+1):
                    fnVtxComp.addElement( i )

                list.add( path, vtxComp )

        else:
            ## Pass this to the parent class
            result = om.MPxSurfaceShape.matchComponent(self, item, spec, list )

        return result

    def match(self, mask, componentList):
        ##
        ## Description:
        ##
        ##      Check for matches between selection type / component list, and
        ##      the type of this shape / or it's components
        ##
        ##      This is used by sets and deformers to make sure that the selected
        ##      components fall into the "vertex only" category.
        ##
        ## Arguments
        ##
        ##      mask          - selection type mask
        ##      componentList - possible component list
        ##
        ## Returns
        ##      True if matched any
        ##

        result = False

        if len(componentList) == 0:
            result = mask.intersects( om.MSelectionMask.kSelectMeshes )

        else:
            for comp in componentList:
                if comp.apiType() == om.MFn.kMeshVertComponent and mask.intersects(om.MSelectionMask.kSelectMeshVerts):
                    result = True
                    break

        return result

    ## Support deformers (components)
    ##
    def createFullVertexGroup(self):
        ##
        ## Description
        ##     This method is used by maya when it needs to create a component
        ##     containing every vertex (or control point) in the shape.
        ##     This will get called if you apply some deformer to the whole
        ##     shape, i.e. select the shape in object mode and add a deformer to it.
        ##
        ## Returns
        ##
        ##    A "complete" component representing all vertices in the shape.
        ##

        ## Create a vertex component
        ##
        fnComponent = om.MFnSingleIndexedComponent()
        fullComponent = fnComponent.create( om.MFn.kMeshVertComponent )

        ## Set the component to be complete, i.e. the elements in
        ## the component will be [0:numVertices-1]
        ##
        numVertices = len(self.meshGeom().vertices)
        fnComponent.setCompleteData( numVertices )

        return fullComponent

    def getShapeSelectionMask(self):
        ##
        ## Description
        ##     This method is overriden to support interactive object selection in Viewport 2.0
        ##
        ## Returns
        ##
        ##    The selection mask of the shape
        ##

        selType = om.MSelectionMask.kSelectMeshes
        return om.MSelectionMask( selType )

    def getComponentSelectionMask(self):
        ##
        ## Description
        ##     This method is overriden to support interactive component selection in Viewport 2.0
        ##
        ## Returns
        ##
        ##    The mask of the selectable components of the shape
        ##

        selMask = om.MSelectionMask(om.MSelectionMask.kSelectMeshVerts)
        selMask.addMask(om.MSelectionMask.kSelectMeshEdges)
        selMask.addMask(om.MSelectionMask.kSelectMeshFaces)
        return selMask

    def localShapeInAttr(self):
        ##
        ## Description
        ##
        ##    Returns the input attribute of the shape. This is used by
        ##    maya to establish input connections for deformers etc.
        ##    This attribute must be data of type kGeometryData.
        ##
        ## Returns
        ##
        ##    input attribute for the shape
        ##

        return apiMesh.inputSurface

    def localShapeOutAttr(self):
        ##
        ## Description
        ##
        ##    Returns the output attribute of the shape. This is used by
        ##    maya to establish out connections for deformers etc.
        ##    This attribute must be data of type kGeometryData.
        ##
        ## Returns
        ##
        ##    output attribute for the shape
        ##
        ##

        return apiMesh.outputSurface

    def worldShapeOutAttr(self):
        ##
        ## Description
        ##
        ##    Returns the output attribute of the shape. This is used by
        ##    maya to establish out connections for deformers etc.
        ##    This attribute must be data of type kGeometryData.
        ##
        ## Returns
        ##
        ##    output attribute for the shape
        ##
        ##

        return apiMesh.outputSurface

    def cachedShapeAttr(self):
        ##
        ## Description
        ##
        ##    Returns the cached shape attribute of the shape.
        ##    This attribute must be data of type kGeometryData.
        ##
        ## Returns
        ##
        ##    cached shape attribute
        ##

        return apiMesh.cachedSurface


    def geometryData(self):
        ##
        ## Description
        ##
        ##    Returns the data object for the surface. This gets
        ##    called internally for grouping (set) information.
        ##

        datablock = self.forceCache()
        handle = datablock.inputValue( apiMesh.inputSurface )
        return handle.data()

    def closestPoint(self, toThisPoint, theClosestPoint, tolerance):
        ##
        ## Description
        ##
        ##      Returns the closest point to the given point in space.
        ##      Used for rigid bind of skin.  Currently returns wrong results;
        ##      override it by implementing a closest point calculation.

        ## Iterate through the geometry to find the closest point within
        ## the given tolerance.
        ##
        geometry = self.meshGeom()
        numVertices = len(geometry.vertices)
        for i in xrange(numVertices):
            tryThisOne = geometry.vertices[i]

        ## Set the output point to the result (hardcode for debug just now)
        ##
        theClosestPoint = geometry.vertices[0]

    ## Support the translate/rotate/scale tool (components)
    ##
    def transformUsing(self, mat, componentList, cachingMode=om.MPxSurfaceShape.kNoPointCaching, pointCache=None):
        ##
        ## Description
        ##
        ##    Transforms the given components. This method is used by
        ##    the move, rotate, and scale tools in component mode.
        ##    The bounding box has to be updated here, so do the normals and
        ##    any other attributes that depend on vertex positions.
        ##
        ## Arguments
        ##    mat           - matrix to tranform the components by
        ##    componentList - list of components to be transformed,
        ##                    or an empty list to indicate the whole surface
        ##    cachingMode   - how to use the supplied pointCache (kSavePoints, kRestorePoints)
        ##    pointCache    - if non-None, save or restore points from this list base
        ##                    on the cachingMode
        ##

        geometry = self.meshGeom()

        ## Create cachingMode boolean values for clearer reading of conditional code below
        ##
        savePoints    = (cachingMode == om.MPxSurfaceShape.kSavePoints and pointCache is not None)
        restorePoints = (cachingMode == om.MPxSurfaceShape.kRestorePoints and pointCache is not None)

        cacheIndex = 0
        cacheLen = 0
        if pointCache:
            cacheLen = len(pointCache)

        if restorePoints:
            ## restore the points based on the data provided in the pointCache attribute
            ##
            if len(componentList) > 0:
                ## traverse the component list
                ##
                for comp in componentList:
                    fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
                    elemCount = fnComp.elementCount

                    for idx in xrange(elementCount):
                        elemIndex = fnComp.element(idx)
                        geometry.vertices[elemIndex] = pointCache[cacheIndex]
                        cacheIndex += 1
                        if cacheIndex >= cacheLen:
                            break

                    if cacheIndex >= cacheLen:
                        break

            else:
                ## if the component list is of zero-length, it indicates that we
                ## should transform the entire surface
                ##
                vertLen = len(geometry.vertices)
                for idx in xrange(vertLen):
                    geometry.vertices[idx] = pointCache[cacheIndex]
                    cacheIndex += 1
                    if cacheIndex >= cacheLen:
                        break

        else:
            ## Transform the surface vertices with the matrix.
            ## If savePoints is True, save the points to the pointCache.
            ##
            if len(componentList) > 0:
                ## Traverse the componentList
                ##
                setSizeIncrement = True
                for comp in componentList:
                    fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
                    elemCount = fnComp.elementCount

                    if savePoints and setSizeIncrement:
                        pointCache.sizeIncrement = elemCount
                        setSizeIncrement = False

                    for idx in xrange(elemCount):
                        elemIndex = fnComp.element(idx)
                        if savePoints:
                            pointCache.append(geometry.vertices[elemIndex])

                        geometry.vertices[elemIndex] *= mat
                        geometry.normals[idx] = geometry.normals[idx].transformAsNormal( mat )

            else:
                ## If the component list is of zero-length, it indicates that we
                ## should transform the entire surface
                ##
                vertLen = len(geometry.vertices)
                if savePoints:
                    pointCache.sizeIncrement = vertLen

                for idx in xrange(vertLen):
                    if savePoints:
                        pointCache.append(geometry.vertices[idx])

                    geometry.vertices[idx] *= mat
                    geometry.normals[idx] = geometry.normals[idx].transformAsNormal( mat )

        ## Update the surface
        self.updateCachedSurface( geometry, componentList )

    def tweakUsing(self, mat, componentList, cachingMode, pointCache, handle):
        ##
        ## Description
        ##
        ##    Transforms the given components. This method is used by
        ##    the move, rotate, and scale tools in component mode when the
        ##    tweaks for the shape are stored on a separate tweak node.
        ##    The bounding box has to be updated here, so do the normals and
        ##    any other attributes that depend on vertex positions.
        ##
        ## Arguments
        ##    mat           - matrix to tranform the components by
        ##    componentList - list of components to be transformed,
        ##                    or an empty list to indicate the whole surface
        ##    cachingMode   - how to use the supplied pointCache (kSavePoints, kRestorePoints, kUpdatePoints)
        ##    pointCache    - if non-null, save or restore points from this list base
        ##                    on the cachingMode
        ##    handle        - handle to the attribute on the tweak node where the
        ##                    tweaks should be stored
        ##

        geometry = self.meshGeom()

        ## Create cachingMode boolean values for clearer reading of conditional code below
        ##
        savePoints    = (cachingMode == om.MPxSurfaceShape.kSavePoints and pointCache is not None)
        updatePoints  = (cachingMode == om.MPxSurfaceShape.kUpdatePoints and pointCache is not None)
        restorePoints = (cachingMode == om.MPxSurfaceShape.kRestorePoints and pointCache is not None)

        builder = handle.builder()

        cacheIndex = 0
        cacheLen = 0
        if pointCache:
            cacheLen = len(pointCache)

        if restorePoints:
            ## restore points from the pointCache
            ##
            if len(componentList) > 0:
                ## traverse the component list
                ##
                for comp in componentList:
                    fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
                    elemCount = fnComp.elementCount

                    for idx in xrange(elementCount):
                        elemIndex = fnComp.element(idx)
                        cachePt = pointCache[cacheIndex]
                        elem = builder.addElement( elemIndex )
                        elem.set3Double(cachePt.x, cachePt.y, cachePt.z)
                        cacheIndex += 1
                        if cacheIndex >= cacheLen:
                            break

                    if cacheIndex >= cacheLen:
                        break

            else:
                ## if the component list is of zero-length, it indicates that we
                ## should transform the entire surface
                ##
                vertLen = len(geometry.vertices)
                for idx in xrange(vertLen):
                    cachePt = pointCache[cacheIndex]
                    elem = builder.addElement( idx )
                    elem.set3Double(cachePt.x, cachePt.y, cachePt.z)
                    cacheIndex += 1
                    if cacheIndex >= cacheLen:
                        break

        else:
            ## Tweak the points. If savePoints is True, also save the tweaks in the
            ## pointCache. If updatePoints is True, add the new tweaks to the existing
            ## data in the pointCache.
            ##
            if len(componentList) > 0:
                setSizeIncrement = True
                for comp in componentList:
                    fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
                    elemCount = fnComp.elementCount

                    if savePoints and setSizeIncrement:
                        pointCache.sizeIncrement = elemCount
                        setSizeIncrement = False

                    for idx in xrange(elementCount):
                        elemIndex = fnComp.element(idx)
                        currPt = newPt = geometry.vertices[elemIndex]
                        newPt *= mat
                        delta = newPt - currPt
                        elem = builder.addElement( elemIndex )
                        elem.set3Double(delta.x, delta.y, delta.z)

                        if savePoints:
                            ## store the points in the pointCache for undo
                            ##
                            pointCache.append(delta*(-1.0))

                        elif updatePoints and cacheIndex < cacheLen:
                            pointCache[cacheIndex] = pointCache[cacheIndex] - delta
                            cacheIndex += 1

            else:
                ## if the component list is of zero-length, it indicates that we
                ## should transform the entire surface
                ##
                vertLen = len(geometry.vertices)
                if savePoints:
                    pointCache.sizeIncrement = vertLen

                for idx in xrange(vertLen):
                    currPt = newPt = geometry.vertices[idx]
                    newPt *= mat
                    delta = newPt - currPt
                    elem = builder.addElement( idx )
                    elem.set3Double(delta.x, delta.y, delta.z)

                    if savePoints:
                        ## store the points in the pointCache for undo
                        ##
                        pointCache.append(delta*(-1.0))

                    elif updatePoints and idx < cacheLen:
                        pointCache[cacheIndex] = pointCache[cacheIndex] - delta
                        cacheIndex += 1

        ## Set the builder into the handle.
        ##
        handle.set(builder)

        ## Tell maya the bounding box for this object has changed
        ## and thus "boundingBox()" needs to be called.
        ##
        self.childChanged( om.MPxSurfaceShape.kBoundingBoxChanged )

        ## Signal to the viewport that it needs to update the object
        self.signalDirtyToViewport()

    ## Support the soft-select translate/rotate/scale tool (components)
    ##
    def weightedTransformUsing(self, xform, space, componentList, cachingMode, pointCache, freezePlane):
        ##
        ## Description
        ##
        ##    Transforms the given soft-selected components interpolated using the specified weights.
        ##    This method is used by the move, rotate, and scale tools in component mode.
        ##    The bounding box has to be updated here, so do the normals and
        ##    any other attributes that depend on vertex positions.
        ##    It is similar to the transformUsing() virtual function.
        ##
        ## Arguments
        ##
        ##    xform           the matrix representing the transformation that is to be applied to the components
        ##    space           the matrix representing the transformation space to perform the interpolated transformation.
        ##                    A value of None indicates it should be ignored.
        ##    componentList   a list of components to be transformed and their weights.  This list will not be empty.
        ##    cachingMode     whether the points should be added/updated in the pointCache, or restored from
        ##                    the pointCache, or transform using the original values in the pointCache.
        ##    pointCache      used to store for undo and restore points during undo
        ##    freezePlane     used for symmetric transformation of components.  A value of None indicates
        ##                    it is not used and there is no symmetric transformation.
        ##

        ## For example purposes only, use the default MPxSurfaceShape.weightedTransformUsing() if the
        ## useWeightedTransformUsingFunction is False
        ##
        plg_useWeightedTransformUsingFunction = om.MPlug( self.thisMObject(), apiMesh.useWeightedTransformUsingFunction )
        val_useWeightedTransformUsingFunction = plg_useWeightedTransformUsingFunction.asBool()
        if not val_useWeightedTransformUsingFunction:
            om.MPxSurfaceShape.weightedTransformUsing(self, xform, space, componentList, cachingMode, pointCache, freezePlane)
            self.signalDirtyToViewport()
            return

        ## Create cachingMode boolean values for clearer reading of conditional code below
        ##
        savePoints          = (cachingMode == om.MPxSurfaceShape.kSavePoints and pointCache is not None)
        updatePoints        = (cachingMode == om.MPxSurfaceShape.kUpdatePoints and pointCache is not None)
        restorePoints       = (cachingMode == om.MPxSurfaceShape.kRestorePoints and pointCache is not None)
        transformOrigPoints = (cachingMode == om.MPxSurfaceShape.kTransformOriginalPoints and pointCache is not None)

        ## Pre-calculate parameters
        spaceInv = om.MMatrix()
        if space:
            spaceInv = space.inverse()

        ## Traverse the componentList and modify the control points
        ##
        geometry = self.meshGeom()
        almostZero = 1.0e-5 ## Hardcoded tolerance
        pointCacheIndex = 0
        setSizeIncrement = True

        for comp in componentList:
            fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
            elemCount = fnComp.elementCount
            hasWeights = fnComp.hasWeights
            hasSeam = (freezePlane is not None)

            if savePoints and setSizeIncrement:
                pointCache.sizeIncrement = elemCount
                setSizeIncrement = False

            for idx in xrange(elementCount):
                elemIndex = fnComp.element( idx )
                perc = 1.0
                if hasWeights:
                    perc = fnComp.weight(idx).influence()   ## get the weight for the component

                ## Only act upon points (store in pointCache, transform, etc) that have a non-zero weight
                if perc > almostZero:   ## if the point has enough weight to be transformed
                    if restorePoints:
                        ## restore the original point from the point cache
                        geometry.vertices[elemIndex] = om.MVector( pointCache[pointCacheIndex] )
                        pointCacheIndex += 1

                    else:   ## perform point transformation
                        ## Update the pointCache with the original value
                        if savePoints:
                            pointCache.append( geometry.vertices[elemIndex] )

                        elif transformOrigPoints:   ## start by reverting points back to their original values stored in the pointCache for the transformation
                            geometry.vertices[elemIndex] = om.MVector( pointCache[pointCacheIndex] )

                        elif updatePoints:  ## update the pointCache with the current values
                            pointCache[pointCacheIndex] = geometry.vertices[elemIndex]

                        ## Compute interpolated transformation matrix
                        mat = om.MMatrix()
                        if perc == 1.0:
                            mat = xform.asMatrix()
                        elif space:
                            mat = space * xform.asMatrix(perc) * spaceInv
                        else:
                            mat = xform.asMatrix(perc)

                        ## transform to new position
                        currPt = newPt = geometry.vertices[elemIndex]
                        newPt *= mat

                        ## handle symmetry and reflection
                        if hasSeam and fnComp.weight(idx).seam() > 0.0:
                            newPt += freezePlane.normal() * (fnComp.weight(idx).seam() * (freezePlane.directedDistance(currPt) - freezePlane.directedDistance(newPt)))

                        ## Update the geometry with the new point
                        geometry.vertices[elemIndex] = newPt
                        pointCacheIndex += 1

        ## Update the surface
        self.updateCachedSurface( geometry, componentList )

    def weightedTweakUsing(self, xform, space, componentList, cachingMode, pointCache, freezePlane, handle):
        ##
        ## Description
        ##
        ##    Transforms the given soft-selected components interpolated using the specified weights.
        ##    This method is used by the move, rotate, and scale tools in component mode when the
        ##    tweaks for the shape are stored on a separate tweak node.
        ##    The bounding box has to be updated here, so do the normals and
        ##    any other attributes that depend on vertex positions.
        ##
        ##    It is similar to the tweakUsing() virtual function and is based on apiMesh.tweakUsing().
        ##
        ##
        ## Arguments
        ##
        ##    xform           the matrix representing the transformation that is to be applied to the components
        ##    space           the matrix representing the transformation space to perform the interpolated transformation.
        ##                    A value of None indicates it should be ignored.
        ##    componentList   a list of components to be transformed and their weights.  This list will not be empty.
        ##    cachingMode     whether the points should be added/updated in the pointCache, or restored from
        ##                    the pointCache, or transform using use the original values in the pointCache.
        ##    pointCache      used to store for undo and restore points during undo
        ##    freezePlane     used for symmetric transformation of components.  A value of None indicates
        ##                    it is not used and there is no symmetric transformation.
        ##    handle        - handle to the attribute on the tweak node where the
        ##                    tweaks should be stored
        ##
    
        ## For example purposes only, use the default MPxSurfaceShape.weightedTweakUsing() if the
        ## useWeightedTweakUsingFunction is False
        ##
        plg_useWeightedTweakUsingFunction = om.MPlug( self.thisMObject(), apiMesh.useWeightedTweakUsingFunction )
        val_useWeightedTweakUsingFunction = plg_useWeightedTweakUsingFunction.asBool()
        if not val_useWeightedTweakUsingFunction:
            om.MPxSurfaceShape.weightedTweakUsing(self, xform, space, componentList, cachingMode, pointCache, freezePlane, handle)
            return

        geometry = self.meshGeom()

        ## Create cachingMode boolean values for clearer reading of conditional code below
        ##
        savePoints          = (cachingMode == om.MPxSurfaceShape.kSavePoints and pointCache is not None)
        updatePoints        = (cachingMode == om.MPxSurfaceShape.kUpdatePoints and pointCache is not None)
        restorePoints       = (cachingMode == om.MPxSurfaceShape.kRestorePoints and pointCache is not None)
        transformOrigPoints = (cachingMode == om.MPxSurfaceShape.kTransformOriginalPoints and pointCache is not None)

        builder = handle.builder()

        cacheIndex = 0
        cacheLen = 0
        if pointCache:
            cacheLen = len(pointCache)

        if restorePoints:
            ## restore points from the pointCache
            ##
            ## traverse the component list
            ##
            for comp in componentList:
                fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
                elemCount = fnComp.elementCount

                for idx in xrange(elementCount):
                    elemIndex = fnComp.element( idx )
                    cachePt = pointCache[cacheIndex]
                    elem = builder.addElement( elemIndex )
                    elem.set3Double(cachePt.x, cachePt.y, cachePt.z)
                    cacheIndex += 1
                    if cacheIndex >= cacheLen:
                        break

        else:
            ## Tweak the points. If savePoints is True, also save the tweaks in the
            ## pointCache. If updatePoints is True, add the new tweaks to the existing
            ## data in the pointCache.
            ##

            ## Specify a few parameters (for weighted transformation)
            almostZero = 1.0e-5 ## Hardcoded tolerance
            setSizeIncrement = True
            spaceInv = om.MMatrix()
            if space:
                spaceInv = space.inverse()

            for comp in componentList:
                fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
                elemCount = fnComp.elementCount
                hasWeights = fnComp.hasWeights ## (for weighted transformation)
                hasSeam = (freezePlane is not None)  ## (for weighted transformation)

                if savePoints and setSizeIncrement:
                    pointCache.sizeIncrement = elemCount
                    setSizeIncrement = False

                for idx in xrange(elementCount):
                    elemIndex = fnComp.element( idx )
                    perc = 1.0
                    if hasWeights:
                        perc = fnComp.weight(idx).influence()   ## get the weight for the component

                    ## Only act upon points (store in pointCache, transform, etc) that have a non-zero weight
                    if perc > almostZero:   ## if the point has enough weight to be transformed (for weighted transformation)

                        ## Compute interpolated transformation matrix (for weighted transformation)
                        ##
                        mat = om.MMatrix()
                        if perc == 1.0:
                            mat = xform.asMatrix()
                        elif space:
                            mat = space * xform.asMatrix(perc) * spaceInv
                        else:
                            mat = xform.asMatrix(perc)

                        ## Start by reverting points back to their original values stored in
                        ## the pointCache for the transformation
                        ##
                        if transformOrigPoints:
                            geometry.vertices[elemIndex] = om.MVector( pointCache[cacheIndex] )

                        ## Perform transformation of the point
                        ##
                        currPt = newPt = geometry.vertices[elemIndex]
                        newPt *= mat

                        ## Handle symmetry and reflection (for weighted transformation)
                        ##
                        if hasSeam and fnComp.weight(idx).seam() > 0.0:
                            newPt += freezePlane.normal() * (fnComp.weight(idx).seam() * (freezePlane.directedDistance(currPt) - freezePlane.directedDistance(newPt)))

                        ## Calculate deltas and final positions
                        delta = newPt - currPt

                        elem = builder.addElement( elemIndex )
                        elem.set3Double(delta.x, delta.y, delta.z)

                        if savePoints:
                            ## store the points in the pointCache for undo
                            ##
                            pointCache.append(delta*(-1.0))
                        elif updatePoints and cacheIndex < cacheLen:
                            pointCache[cacheIndex] = pointCache[cacheIndex] - delta
                            cacheIndex += 1

        ## Set the builder into the handle.
        ##
        handle.set(builder)

        ## Tell maya the bounding box for this object has changed
        ## and thus "boundingBox()" needs to be called.
        ##
        self.childChanged( om.MPxSurfaceShape.kBoundingBoxChanged )

    ## Support the move tools normal/u/v mode (components)
    ##
    def vertexOffsetDirection(self, component, direction, mode, normalize):
        ##
        ## Description
        ##
        ##    Returns offsets for the given components to be used my the
        ##    move tool in normal/u/v mode.
        ##
        ## Arguments
        ##
        ##    component - components to calculate offsets for
        ##    direction - array of offsets to be filled
        ##    mode      - the type of offset to be calculated
        ##    normalize - specifies whether the offsets should be normalized
        ##
        ## Returns
        ##
        ##    True if the offsets could be calculated, False otherwise
        ##

        fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(component) )
        if component.apiType() != om.MFn.kMeshVertComponent:
            return False

        geometry = self.meshGeom()
        if not geometry:
            return False

        ## For each vertex add the appropriate offset
        ##
        for idx in fnComp:
            normal = geometry.normals[ idx ]

            if mode == om.MPxSurfaceShape.kNormal:
                if normalize:
                    normal.normalize()
                direction.append( normal )

            else:
                ## Construct an orthonormal basis from the normal
                ## uAxis, and vAxis are the new vectors.
                ##
                normal.normalize()

                i = 0
                a = math.abs(normal[0])

                if a < math.abs(normal[1]):
                   i = 1
                   a = fabs(normal[1])

                if a < math.abs(normal[2]):
                   i = 2

                j = (i+1)%3
                k = (j+1)%3

                a = math.sqrt(normal[i]*normal[i] + normal[j]*normal[j])
                uAxis[i] = -normal[j]/a
                uAxis[j] =  normal[i]/a
                uAxis[k] = 0.0
                vAxis = normal^uAxis

                if mode == om.MPxSurfaceShape.kUTangent or mode == om.MPxSurfaceShape.kUVNTriad:
                    if normalize:
                        uAxis.normalize()
                    direction.append( uAxis )

                if mode == om.MPxSurfaceShape.kVTangent or mode == om.MPxSurfaceShape.kUVNTriad:
                    if normalize:
                        vAxis.normalize()
                    direction.append( vAxis )

                if mode == om.MPxSurfaceShape.kUVNTriad:
                    if normalize:
                        normal.normalize()
                    direction.append( normal )

        return True

    ## Bounding box methods
    ##
    def isBounded(self):
        ##
        ## Description
        ##
        ##    Specifies that this object has a boundingBox.
        ##

        return True

    def boundingBox(self):
        ##
        ## Description
        ##
        ##    Returns the bounding box for this object.
        ##    It is a good idea not to recompute here as this funcion is called often.
        ##
        if self.fShapeDirty:
            # Update:
            self.meshObject()

        thisNode = self.thisMObject()
        c1Plug = om.MPlug( thisNode, apiMesh.bboxCorner1 )
        c2Plug = om.MPlug( thisNode, apiMesh.bboxCorner2 )
        corner1Object = c1Plug.asMObject()
        corner2Object = c2Plug.asMObject()

        fnData = om.MFnNumericData()
        fnData.setObject( corner1Object )
        corner1 = fnData.getData()

        fnData.setObject( corner2Object )
        corner2 = fnData.getData()

        corner1Point = om.MPoint( corner1[0], corner1[1], corner1[2] )
        corner2Point = om.MPoint( corner2[0], corner2[1], corner2[2] )

        return om.MBoundingBox( corner1Point, corner2Point )

    ## Associates a user defined iterator with the shape (components)
    ##
    def geometryIteratorSetup(self, componentList, components, forReadOnly=False):
        ##
        ## Description
        ##
        ##    Creates a geometry iterator compatible with his shape.
        ##
        ## Arguments
        ##
        ##    componentList - list of components to be iterated
        ##    components    - component to be iterator
        ##    forReadOnly   -
        ##
        ## Returns
        ##
        ##    An iterator for the components
        ##

        if components.isNull():
            vtxComponents = om.MObjectArray([self.convertToVertexComponent(c) for c in componentList])
            return apiMeshGeomIterator( self.meshGeom(), vtxComponents )

        return apiMeshGeomIterator( self.meshGeom(), self.convertToVertexComponent(components) )

    def acceptsGeometryIterator(self, arg0, arg1=None, arg2=None):
        ##
        ## Description
        ##
        ##    Specifies that this shape can provide an iterator for getting/setting
        ##    control point values.
        ##
        ## Arguments
        ##
        ##    writable   - maya asks for an iterator that can set points if this is True
        ##
        ##    OR
        ##
        ##    component   - the component
        ##    writable    - maya asks for an iterator that can set points if this is True
        ##    forReadOnly - maya asking for an iterator for querying only
        ##

        return True

    ##########################################################
    ##
    ## Helper methods
    ##
    ##########################################################

    def hasHistory(self):
        ##
        ## Description
        ##
        ##    Returns True if the shape has input history, False otherwise.
        ##
        return self.fHasHistoryOnCreate

    def shapeDirty(self):
        ##
        ## Description
        ##
        ##    Returns True if the input surface of the shape has been dirtied since
        ##    the last reset of the flag
        ##
        return self.fShapeDirty

    def resetShapeDirty(self):
        ##
        ## Description
        ##
        ##    Reset the shape dirty state of the node
        ##
        self.fShapeDirty = False

    def materialDirty(self):
        ##
        ## Description
        ##
        ##    Returns true if the shading group of the shape has been changed since
        ##    the last reset of the flag
        ##
        return self.fMaterialDirty

    def setMaterialDirty(self, dirty):
        ##
        ## Description
        ##
        ##    Reset the material dirty state of the node
        ##
        self.fMaterialDirty = dirty

    def computeInputSurface(self, plug, datablock):
        ##
        ## Description
        ##
        ##    If there is input history, evaluate the input attribute
        ##

        ## Get the input surface if there is history
        ##
        if self.hasHistory():
            inputHandle = datablock.inputValue( apiMesh.inputSurface )

            surf = inputHandle.asPluginData()
            if not isinstance(surf, apiMeshData):
                raise RuntimeError("computeInputSurface : invalid inputSurface data found")

            ## Create the cachedSurface and copy the input surface into it
            ##
            fnDataCreator = om.MFnPluginData()
            fnDataCreator.create( apiMeshData.id )

            newCachedData = fnDataCreator.data()
            if not isinstance(newCachedData, apiMeshData):
                raise RuntimeError("computeInputSurface : invalid proxy cached apiMeshData object")

            newCachedData.fGeometry.copy(surf.fGeometry)

            cachedHandle = datablock.outputValue( apiMesh.cachedSurface )
            if not isinstance(cachedHandle, om.MDataHandle):
                raise RuntimeError("computeInputSurface : invalid cachedSurface")

            cachedHandle.setMPxData( newCachedData )

    def computeOutputSurface(self, plug, datablock):
        ##
        ## Description
        ##
        ##    Compute the outputSurface attribute.
        ##
        ##    If there is no history, use cachedSurface as the
        ##    input surface. All tweaks will get written directly
        ##    to it. Output is just a copy of the cached surface
        ##    that can be connected etc.
        ##

        ## Check for an input surface. The input surface, if it
        ## exists, is copied to the cached surface.
        ##
        self.computeInputSurface( plug, datablock )

        ## Get a handle to the cached data
        ##
        cachedHandle = datablock.outputValue( apiMesh.cachedSurface )
        if not isinstance(cachedHandle, om.MDataHandle):
            raise RuntimeError("computeOutputSurface : invalid cachedSurface")

        cached = cachedHandle.asPluginData()
        if not isinstance(cached, apiMeshData):
            raise RuntimeError("computeOutputSurface : invalid cachedSurface data found")

        datablock.setClean( plug )

        ## Apply any vertex offsets.
        ##
        if self.hasHistory():
            self.applyTweaks( datablock, cached.fGeometry )

        else:
            cpHandle = datablock.inputArrayValue( om.MPxSurfaceShape.mControlPoints )
            cpHandle.setAllClean()

        ## Create some output data
        ##
        fnDataCreator = om.MFnPluginData()
        fnDataCreator.create( apiMeshData.id )

        newData = fnDataCreator.data()
        if not isinstance(newData, apiMeshData):
            raise RuntimeError("computeOutputSurface : invalid proxy cached apiMeshData object")

        ## Copy the data
        ##
        newData.fGeometry.copy(cached.fGeometry)

        ## Assign the new data to the outputSurface handle
        ##
        outHandle = datablock.outputValue( apiMesh.outputSurface )
        outHandle.setMPxData( newData )

        ## Update the bounding box attributes
        ##
        self.computeBoundingBox( datablock )

    def computeWorldSurface(self, plug, datablock):
        ##
        ## Description
        ##
        ##    Compute the worldSurface attribute.
        ##

        self.computeOutputSurface( plug, datablock )
        inHandle = datablock.outputValue( apiMesh.outputSurface )
        outSurf = inHandle.asPluginData()
        if not isinstance(outSurf, apiMeshData):
            raise RuntimeError("computeWorldSurface : invalid outSurf")

        ## Create some output data
        ##
        fnDataCreator = om.MFnPluginData()
        fnDataCreator.create( apiMeshData.id )

        newData = fnDataCreator.data()
        if not isinstance(newData, apiMeshData):
            raise RuntimeError("computeWorldSurface : invalid proxy cached apiMeshData object")

        ## Get worldMatrix from MPxSurfaceShape and set it to MPxGeometryData
        worldMat = self.getWorldMatrix(datablock, 0)
        newData.matrix = worldMat

        ## Copy the data
        ##
        newData.fGeometry.copy( outSurf.fGeometry )

        ## Assign the new data to the outputSurface handle
        ##
        arrayIndex = plug.logicalIndex()

        worldHandle = datablock.outputArrayValue( apiMesh.worldSurface )
        builder = worldHandle.builder()
        outHandle = builder.addElement( arrayIndex )

        outHandle.setMPxData( newData )

    def computeBoundingBox(self, datablock):
        ##
        ## Description
        ##
        ##    Use the larges/smallest vertex positions to set the corners
        ##    of the bounding box.
        ##

        ## Update bounding box
        ##
        lowerHandle = datablock.outputValue( apiMesh.bboxCorner1 )
        upperHandle = datablock.outputValue( apiMesh.bboxCorner2 )

        geometry = self.meshGeom()
        cnt = len(geometry.vertices)
        if cnt == 0:
            return

        ## This clears any old bbox values
        ##
        tmppnt = geometry.vertices[0]
        lower = [ tmppnt[0], tmppnt[1], tmppnt[2] ]
        upper = [ tmppnt[0], tmppnt[1], tmppnt[2] ]

        for i in xrange(cnt):
            pnt = geometry.vertices[i]

            if pnt[0] < lower[0]:   lower[0] = pnt[0]
            if pnt[1] < lower[1]:   lower[1] = pnt[1]
            if pnt[2] < lower[2]:   lower[2] = pnt[2]

            if pnt[0] > upper[0]:   upper[0] = pnt[0]
            if pnt[1] > upper[1]:   upper[1] = pnt[1]
            if pnt[2] > upper[2]:   upper[2] = pnt[2]

        lowerHandle.set3Double(lower[0], lower[1], lower[2])
        upperHandle.set3Double(upper[0], upper[1], upper[2])

        lowerHandle.setClean()
        upperHandle.setClean()

        ## Signal that the bounding box has changed.
        ##
        self.childChanged( om.MPxSurfaceShape.kBoundingBoxChanged )
        
    def convertToVertexComponent(self, components):
        """
            Converts edge and face components into vertex components. This
            allows applying transform offsets to the vertex when edge or faces
            are selected.
        """
        retVal = components

        try:
            srcComponent = om.MFnSingleIndexedComponent(components)
            srcComponentType = srcComponent.componentType
        except:
            return components
        
        if srcComponentType != om.MFn.kMeshVertComponent:
            srcIndices = set(srcComponent.getElements())
            retVal = srcComponent.create(om.MFn.kMeshVertComponent)
            vtxComponent = om.MFnSingleIndexedComponent(retVal)
            
            geomPtr = self.meshGeom()
            
            base = 0
            edgeId = 0
            for faceIdx in xrange(0, geomPtr.faceCount):
                # ignore degenerate faces
                numVerts = geomPtr.face_counts[faceIdx]
                if numVerts > 2:
                    for v in xrange(0, numVerts):
                        if srcComponentType == om.MFn.kMeshEdgeComponent:
                            if edgeId in srcIndices:
                                vindex1 = base + (v % numVerts)
                                vindex2 = base + ((v+1) % numVerts)

                                vertexId1 = geomPtr.face_connects[vindex1]
                                vertexId2 = geomPtr.face_connects[vindex2]

                                vtxComponent.addElement(vertexId1)
                                vtxComponent.addElement(vertexId2)

                            edgeId += 1
                        else:
                            # Face component:
                            if faceIdx in srcIndices:
                                vindex = base + (v % numVerts)
                                vertexId = geomPtr.face_connects[vindex]
                                vtxComponent.addElement(vertexId)

                    base += numVerts;

        return retVal

    def applyTweaks(self, datablock, geometry):
        ##
        ## Description
        ##
        ##    If the shape has history, apply any tweaks (offsets) made
        ##    to the control points.
        ##

        cpHandle = datablock.inputArrayValue( om.MPxSurfaceShape.mControlPoints )

        ## Loop through the component list and transform each vertex.
        ##
        while not cpHandle.isDone():
            elemIndex = cpHandle.elementLogicalIndex()
            pntHandle = cpHandle.outputValue()

            offset = pntHandle.asDouble3()

            ## Apply the tweaks to the output surface
            ##
            geometry.vertices[elemIndex] += om.MPoint(offset[0],offset[1],offset[2])

            cpHandle.next()


    def updateCachedSurface(self, geometry, componentList):
        ##
        ## Description
        ##
        ##    Update the cached surface attribute, handle the tweak history as appropriate,
        ##    and trigger a bounding box change calculation.
        ##
        ## Arguments
        ##    geometry       - the modified geometry to apply to the cached surface attribute
        ##

        ## Retrieve the value of the cached surface attribute.
        ## We will set the new geometry data into the cached surface attribute
        ##
        ## Access the datablock directly. This code has to be efficient
        ## and so we bypass the compute mechanism completely.
        ## NOTE: In general we should always go though compute for getting
        ## and setting attributes.
        ##
        datablock = self.forceCache()

        cachedHandle = datablock.outputValue( apiMesh.cachedSurface )
        cached = cachedHandle.asPluginData()

        dHandle = datablock.outputValue( om.MPxSurfaceShape.mControlPoints )

        ## If there is history then calculate the tweaks necessary for
        ## setting the final positions of the vertices.
        ##
        if self.hasHistory() and cached:
            ## Since the shape has history, we need to store the tweaks (deltas)
            ## between the input shape and the tweaked shape in the control points
            ## attribute.
            ##
            self.buildControlPoints( datablock, len(geometry.vertices) )

            cpHandle = om.MArrayDataHandle( dHandle )

            ## Loop through the component list and transform each vertex.
            ##
            for comp in componentList:
                fnComp = om.MFnSingleIndexedComponent( self.convertToVertexComponent(comp) )
                for elemIndex in fnComp.getElements():
                    cpHandle.jumpToLogicalElement( elemIndex )
                    pntHandle = cpHandle.outputValue()

                    pnt = pntHandle.asDouble3()

                    oldPnt = cached.fGeometry.vertices[elemIndex]
                    newPnt = geometry.vertices[elemIndex]
                    offset = newPnt - oldPnt

                    pnt[0] += offset[0]
                    pnt[1] += offset[1]
                    pnt[2] += offset[2]

                    pntHandle.set3Double(pnt[0], pnt[1], pnt[2])

        ## Copy outputSurface to cachedSurface
        ##
        if cached:
            cached.fGeometry.copy(geometry)

        pCPs = om.MPlug( self.thisMObject(), om.MPxSurfaceShape.mControlPoints)
        pCPs.setMDataHandle(dHandle)

        ## Moving vertices will likely change the bounding box.
        ##
        self.computeBoundingBox( datablock )

        ## Tell maya the bounding box for this object has changed
        ## and thus "boundingBox()" needs to be called.
        ##
        self.childChanged( om.MPxSurfaceShape.kBoundingBoxChanged )

        ## Signal to the viewport that it needs to update the object
        self.signalDirtyToViewport()

    def getPointValue(self, pntInd):
        ##
        ## Description
        ##
        ##    Helper function to return the value of a given vertex
        ##    from the cachedMesh.
        ##
        geometry = self.cachedGeom()
        if geometry:
            return geometry.vertices[ pntInd ]

        return om.MPoint()

    def getChannelValue(self, pntInd, vlInd):
        ##
        ## Description
        ##
        ##    Helper function to return the value of a given vertex
        ##    from the cachedMesh.
        ##
        geometry = self.cachedGeom()
        if geometry:
            return geometry.vertices[ pntInd ][ vlInd ]

        return 0

    def setPointValue(self, pntInd, val):
        ##
        ## Description
        ##
        ##    Helper function to set the value of a given vertex
        ##    in the cachedMesh.
        ##
        geometry = self.cachedGeom()
        if geometry:
            geometry.vertices[ pntInd ] = om.MPoint(val)
    
        self.verticesUpdated()

    def setChannelValue(self, pntInd, vlInd, val):
        ##
        ## Description
        ##
        ##    Helper function to set the value of a given vertex
        ##    in the cachedMesh.
        ##
        geometry = self.cachedGeom()
        if geometry:
            geometry.vertices[ pntInd ][ vlInd ] = val
    
        self.verticesUpdated()

    def meshObject(self):
        ##
        ## Description
        ##
        ##    Get a reference to the mesh data (outputSurface)
        ##    from the datablock. If dirty then an evaluation is
        ##    triggered.
        ##

        ## Get the datablock for this node
        ##
        datablock = self.forceCache()

        ## Calling inputValue will force a recompute if the
        ## connection is dirty. This means the most up-to-date
        ## mesh data will be returned by this method.
        ##
        handle = datablock.inputValue( apiMesh.outputSurface )
        return handle.data()

    def meshGeom(self):
        ##
        ## Description
        ##
        ##    Returns the apiMeshGeom of the outputSurface.
        ##

        fnData = om.MFnPluginData( self.meshObject() )
        data = fnData.data()
        if not isinstance(data, apiMeshData):
            raise RuntimeError("meshGeom : failed to get apiMeshData")

        return data.fGeometry

    def cachedObject(self):
        ##
        ## Description
        ##
        ##    Get a reference to the mesh data (cachedSurface)
        ##    from the datablock. No evaluation is triggered.
        ##

        ## Get the datablock for this node
        ##
        datablock = self.forceCache()
        handle = datablock.outputValue( apiMesh.cachedSurface )
        return handle.data()

    def cachedGeom(self):
        ##
        ## Description
        ##
        ##    Returns the apiMeshGeom of the cachedSurface.
        ##

        fnData = om.MFnPluginData( self.cachedObject() )
        data = fnData.data()
        if not isinstance(data, apiMeshData):
            raise RuntimeError("cachedGeom : failed to get apiMeshData")

        return data.fGeometry

    def buildControlPoints(self, datablock, count):
        ##
        ## Description
        ##
        ##    Check the controlPoints array. If there is input history
        ##    then we will use this array to store tweaks (vertex movements).
        ##

        cpH = datablock.outputArrayValue( om.MPxSurfaceShape.mControlPoints )

        oldBuilder = cpH.builder()
        if count != len(oldBuilder):
            ## Make and set the new builder based on the
            ## info from the old builder.
            builder = om.MArrayDataBuilder( oldBuilder )

            for vtx in xrange(count):
                builder.addElement( vtx )

            cpH.set( builder )

        cpH.setAllClean()

    def verticesUpdated(self):
        ##
        ## Description
        ##
        ##    Helper function to tell maya that this shape's
        ##    vertices have updated and that the bbox needs
        ##    to be recalculated and the shape redrawn.
        ##
        self.childChanged( om.MPxSurfaceShape.kBoundingBoxChanged )
        self.childChanged( om.MPxSurfaceShape.kObjectChanged )

    def setShapeDirty(self):
        self.fShapeDirty = True

    def notifyViewport(self):
        omr.MRenderer.setGeometryDrawDirty(self.thisMObject())

    def signalDirtyToViewport(self):
        self.setShapeDirty()
        self.notifyViewport()

################################################################################
##
## apiMeshShapeUI
##
## Encapsulates the UI portion of a user defined shape. All of the
## drawing and selection code goes here.
##
################################################################################
class apiMeshUI(omui.MPxSurfaceShapeUI):

    @staticmethod
    def creator():
        return apiMeshUI()

    def __init__(self):
        omui.MPxSurfaceShapeUI.__init__(self)

    #####################################################################
    ##
    ## Overrides
    ##
    #####################################################################

    ## Main draw routine for UV editor. This is called by maya when the 
    ## shape is selected and the UV texture window is visible. 
    ## 
    def drawUV(self, view, info):
        ## 
        ## Description: 
        ##   Main entry point for UV drawing. This method is called by the UV 
        ##   texture editor when the shape is 'active'. 
        ## 
        ## Input: 
        ##   A 3dView. 
        ##

        meshNode = self.surfaceShape()
        geom = meshNode.meshGeom()

        if geom.uvcoords.uvcount() > 0:
            view.setDrawColor( om.MColor( (1.0, 0.0, 0.0) ) )
        
            if info.drawingFunction == omui.MTextureEditorDrawInfo.kDrawWireframe: 
                self.drawUVWireframe( geom, view, info )

            elif info.drawingFunction == omui.MTextureEditorDrawInfo.kDrawEverything or info.drawingFunction == omui.MTextureEditorDrawInfo.kDrawUVForSelect:
                self.drawUVWireframe( geom, view, info ) 
                self.drawUVMapCoordNum( geom, view, info, True )

            else:
                self.drawUVWireframe( geom, view, info )

    def canDrawUV(self):
        ##
        ## Description: 
        ##  Tells Maya that this surface shape supports uv drawing. 
        ##

        meshNode = self.surfaceShape()
        geom = meshNode.meshGeom()
        return (geom.uvcoords.uvcount() > 0)

    ## Main selection routine
    ##
    def select(self, selectInfo, selectionList, worldSpaceSelectPts):
        ##
        ## Description:
        ##
        ##     Main selection routine
        ##
        ## Arguments:
        ##
        ##     selectInfo           - the selection state information
        ##     selectionList        - the list of selected items to add to
        ##     worldSpaceSelectPts  -
        ##

        selected = False
        componentSelected = False
        hilited = False

        hilited = (selectInfo.displayStatus() == omui.M3dView.kHilite)
        if hilited:
            componentSelected = self.selectVertices( selectInfo, selectionList, worldSpaceSelectPts )
            selected = selected or componentSelected

        if not selected:
            meshNode = self.surfaceShape()

            ## NOTE: If the geometry has an intersect routine it should
            ## be called here with the selection ray to determine if the
            ## the object was selected.

            selected = True
            priorityMask = om.MSelectionMask( om.MSelectionMask.kSelectNurbsSurfaces )

            item = om.MSelectionList()
            item.add( selectInfo.selectPath() )

            xformedPt = om.MPoint()
            if selectInfo.singleSelection():
                center = meshNode.boundingBox().center
                xformedPt = center
                xformedPt *= selectInfo.selectPath().inclusiveMatrix()

            selectInfo.addSelection( item, xformedPt, selectionList, worldSpaceSelectPts, priorityMask, False )

        return selected

    #####################################################################
    ##
    ## Helper routines
    ##
    #####################################################################

    def selectVertices(self, selectInfo, selectionList, worldSpaceSelectPts):
        ##
        ## Description:
        ##
        ##     Vertex selection.
        ##
        ## Arguments:
        ##
        ##     selectInfo           - the selection state information
        ##     selectionList        - the list of selected items to add to
        ##     worldSpaceSelectPts  -
        ##

        selected = False
        view = selectInfo.view()
        path = selectInfo.multiPath()
        singleSelection = selectInfo.singleSelection()

        ## Create a component that will store the selected vertices
        ##
        fnComponent = om.MFnSingleIndexedComponent()
        surfaceComponent = fnComponent.create( om.MFn.kMeshVertComponent )

        ## if the user did a single mouse click and we find > 1 selection
        ## we will use the alignmentMatrix to find out which is the closest
        ##
        alignmentMatrix = om.MMatrix()
        if singleSelection:
            alignmentMatrix = selectInfo.getAlignmentMatrix()

        singlePoint = om.MPoint()
        selectionPoint = om.MPoint()
        closestPointVertexIndex = -1
        previousZ = 0

        ## Get the geometry information
        ##
        meshNode = self.surfaceShape()
        geom = meshNode.meshGeom()

        ## Loop through all vertices of the mesh and
        ## see if they lie withing the selection area
        ##
        for currentPoint in geom.vertices:
            ## Sets OpenGL's render mode to select and stores
            ## selected items in a pick buffer
            ##
            view.beginSelect()

            glBegin( GL_POINTS )
            glVertex3f( currentPoint[0], currentPoint[1], currentPoint[2] )
            glEnd()

            if view.endSelect() > 0: ## Hit count > 0
                selected = True

                if singleSelection:
                    xformedPoint = currentPoint
                    xformedPoint.homogenize()
                    xformedPoint *= alignmentMatrix
                    z = xformedPoint.z
                    if closestPointVertexIndex < 0 or z > previousZ:
                        closestPointVertexIndex = vertexIndex
                        singlePoint = currentPoint
                        previousZ = z

                else:
                    ## multiple selection, store all elements
                    ##
                    fnComponent.addElement( vertexIndex )

        ## If single selection, insert the closest point into the array
        ##
        if selected and singleSelection:
            fnComponent.addElement(closestPointVertexIndex)

            ## need to get world space position for this vertex
            ##
            selectionPoint = singlePoint
            selectionPoint *= path.inclusiveMatrix()

        ## Add the selected component to the selection list
        ##
        if selected:
            selectionItem = om.MSelectionList()
            selectionItem.add( path, surfaceComponent )

            mask = om.MSelectionMask( om.MSelectionMask.kSelectComponentsMask )
            selectInfo.addSelection( selectionItem, selectionPoint, selectionList, worldSpaceSelectPts, mask, True )

        return selected

    def drawUVWireframe(self, geom, view, info):
        ##
        ## Description: 
        ##  Draws the UV layout in wireframe mode. 
        ## 

        view.beginGL()
        
        ## Draw the polygons
        ##
        vid = 0
        vid_start = vid
        for i in xrange(geom.faceCount):
            glBegin( GL_LINES )

            vid_start = vid 
            for v in xrange(geom.face_counts[i]-1):
                uvId1 = geom.uvcoords.uvId(vid)
                uvId2 = geom.uvcoords.uvId(vid+1)

                uv1 = geom.uvcoords.getUV(uvId1)
                uv2 = geom.uvcoords.getUV(uvId2)

                glVertex3f( uv1[0], uv1[1], 0.0 ) 
                glVertex3f( uv2[0], uv2[1], 0.0 ) 
                vid += 1
            
            uvId1 = geom.uvcoords.uvId(vid)
            uvId2 = geom.uvcoords.uvId(vid_start)

            uv1 = geom.uvcoords.getUV(uvId1)
            uv2 = geom.uvcoords.getUV(uvId2)

            glVertex3f( uv1[0], uv1[1], 0.0 ) 
            glVertex3f( uv2[0], uv2[1], 0.0 ) 
            vid += 1

            glEnd()
        
        view.endGL()

    def drawUVMapCoord(self, view, uvId, uv, drawNumbers):
        ##
        ## Description: 
        ##  Draw the specified uv value into the port view. If drawNumbers is True 
        ##  It will also draw the UV id for the the UV.  
        ##

        if drawNumbers:
            view.drawText( str(uvId), om.MPoint( uv[0], uv[1], 0 ), omui.M3dView.kCenter )

        glVertex3f( uv[0], uv[1], 0.0 )

    def drawUVMapCoordNum(self, geom, view, info, drawNumbers):
        ##
        ## Description: 
        ##  Draw the UV points for all uvs on this surface shape. 
        ##

        view.beginGL() 

        ptSize = glGetFloatv( GL_POINT_SIZE )
        glPointSize( 4.0 )

        for uvId in xrange(geom.uvcoords.uvcount()):
            uv = geom.uvcoords.getUV( uvId )
            self.drawUVMapCoord( view, uvId, uv, drawNumbers )

        glPointSize( ptSize )

        view.endGL() 
        
################################################################################
##
## apiMeshCreator
##
## A DG node that takes a maya mesh as input and outputs apiMeshData.
## If there is no input then the node creates a cube or sphere
## depending on what the shapeType attribute is set to.
##
################################################################################
class apiMeshCreator(om.MPxNode):
    id = om.MTypeId(0x80089)

    ##########################################################
    ##
    ## Attributes
    ##
    ##########################################################
    size = None
    shapeType = None
    inputMesh = None
    outputSurface = None

    @staticmethod
    def creator():
        return apiMeshCreator()

    @staticmethod
    def initialize():
        typedAttr = om.MFnTypedAttribute()
        numericAttr = om.MFnNumericAttribute()
        enumAttr = om.MFnEnumAttribute()

        ## ----------------------- INPUTS -------------------------
        apiMeshCreator.size = numericAttr.create( "size", "sz", om.MFnNumericData.kDouble, 1 )
        numericAttr.array = False
        numericAttr.usesArrayDataBuilder = False
        numericAttr.hidden = False
        numericAttr.keyable = True
        om.MPxNode.addAttribute( apiMeshCreator.size )

        apiMeshCreator.shapeType = enumAttr.create( "shapeType", "st", 0 )
        enumAttr.addField( "cube", 0 )
        enumAttr.addField( "sphere", 1 )
        enumAttr.hidden = False
        enumAttr.keyable = True
        om.MPxNode.addAttribute( apiMeshCreator.shapeType )
        
        apiMeshCreator.inputMesh = typedAttr.create( "inputMesh", "im", om.MFnData.kMesh, om.MObject.kNullObj )
        typedAttr.hidden = True
        om.MPxNode.addAttribute( apiMeshCreator.inputMesh )

        ## ----------------------- OUTPUTS -------------------------
        apiMeshCreator.outputSurface = typedAttr.create( "outputSurface", "os", apiMeshData.id, om.MObject.kNullObj )
        typedAttr.writable = False
        om.MPxNode.addAttribute( apiMeshCreator.outputSurface )

        ## ---------- Specify what inputs affect the outputs ----------
        ##
        om.MPxNode.attributeAffects( apiMeshCreator.inputMesh, apiMeshCreator.outputSurface )
        om.MPxNode.attributeAffects( apiMeshCreator.size, apiMeshCreator.outputSurface )
        om.MPxNode.attributeAffects( apiMeshCreator.shapeType, apiMeshCreator.outputSurface )

    def __init__(self):
        om.MPxNode.__init__(self)

    ##########################################################
    ##
    ## Overrides
    ##
    ##########################################################

    def compute(self, plug, datablock):
        ##
        ## Description
        ##
        ##    When input attributes are dirty this method will be called to
        ##    recompute the output attributes.
        ##

        if plug == apiMeshCreator.outputSurface:
            ## Create some user defined geometry data and access the
            ## geometry so we can set it
            ##
            fnDataCreator = om.MFnPluginData()
            fnDataCreator.create( apiMeshData.id )

            newData = fnDataCreator.data()
            if not isinstance(newData, apiMeshData):
                raise RuntimeError("compute : invalid proxy cached apiMeshData object")

            geometry = newData.fGeometry

            ## If there is an input mesh then copy it's values
            ## and construct some apiMeshGeom for it.
            ##
            hasHistory = self.computeInputMesh( plug, datablock, geometry )
                                                
            ## There is no input mesh so check the shapeType attribute
            ## and create either a cube or a sphere.
            ##
            if not hasHistory:
                sizeHandle = datablock.inputValue( apiMeshCreator.size )
                shape_size = sizeHandle.asDouble()
                typeHandle = datablock.inputValue( apiMeshCreator.shapeType )
                shape_type = typeHandle.asShort()

                if shape_type == 0: ## build a cube
                    self.buildCube( shape_size, geometry )
                elif shape_type == 1: ## build a sphere
                    self.buildSphere( shape_size, 32, geometry )

            geometry.faceCount = len(geometry.face_counts)

            ## Assign the new data to the outputSurface handle
            ##
            outHandle = datablock.outputValue( apiMeshCreator.outputSurface )
            outHandle.setMPxData( newData )
            datablock.setClean( plug )

    ##########################################################
    ##
    ## Helper methods
    ##
    ##########################################################

    def computeInputMesh(self, plug, datablock, geometry):
        ##
        ## Description
        ##
        ##     This function takes an input surface of type kMeshData and converts
        ##     the geometry into this nodes attributes.
        ##     Returns kFailure if nothing is connected.
        ##

        ## Get the input subdiv
        ##        
        inputData = datablock.inputValue( apiMeshCreator.inputMesh )
        surf = inputData.asMesh()

        ## Check if anything is connected
        ##
        thisObj = self.thisMObject()
        surfPlug = om.MPlug( thisObj, apiMeshCreator.inputMesh )
        if not surfPlug.isConnected:
            datablock.setClean( plug )
            return False

        ## Extract the mesh data
        ##
        surfFn = om.MFnMesh(surf)
        geometry.vertices = surfFn.getPoints(om.MSpace.kObject)

        ## Check to see if we have UVs to copy. 
        ##
        hasUVs = surfFn.numUVs() > 0
        uvs = surfFn.getUVs()
        geometry.uvcoords.ucoord = uvs[0]
        geometry.uvcoords.vcoord = uvs[1]

        for i in xrange(surfFn.numPolygons()):
            polyVerts = surfFn.getPolygonVertices(i)

            pvc = len(polyVerts)
            geometry.face_counts.append( pvc )

            for v in xrange(pvc):
                if hasUVs:
                    uvId = surfFn.getPolygonUVid(i, v)
                    geometry.uvcoords.faceVertexIndex.append( uvId )
                geometry.face_connects.append( polyVerts[v] )

        for n in xrange(len(geometry.vertices)):
            normal = surfFn.getVertexNormal(n)
            geometry.normals.append( normal )

        return True

    def buildCube(self, cube_size, geometry):
        ##
        ## Description
        ##
        ##    Constructs a cube
        ##

        geometry.vertices.clear()
        geometry.normals.clear()
        geometry.face_counts.clear()
        geometry.face_connects.clear()
        geometry.uvcoords.reset()

        geometry.vertices.append( om.MPoint( -cube_size, -cube_size, -cube_size ) )
        geometry.vertices.append( om.MPoint(  cube_size, -cube_size, -cube_size ) )
        geometry.vertices.append( om.MPoint(  cube_size, -cube_size, cube_size ) )
        geometry.vertices.append( om.MPoint( -cube_size, -cube_size, cube_size ) )
        geometry.vertices.append( om.MPoint( -cube_size, cube_size, -cube_size ) )
        geometry.vertices.append( om.MPoint( -cube_size, cube_size, cube_size ) )
        geometry.vertices.append( om.MPoint(  cube_size, cube_size, cube_size ) )
        geometry.vertices.append( om.MPoint(  cube_size, cube_size, -cube_size ) )

        normal_value = 0.5775
        geometry.normals.append( om.MVector( -normal_value, -normal_value, -normal_value ) )
        geometry.normals.append( om.MVector(  normal_value, -normal_value, -normal_value ) )
        geometry.normals.append( om.MVector(  normal_value, -normal_value, normal_value ) )
        geometry.normals.append( om.MVector( -normal_value, -normal_value, normal_value ) )
        geometry.normals.append( om.MVector( -normal_value, normal_value, -normal_value ) )
        geometry.normals.append( om.MVector( -normal_value, normal_value, normal_value ) )
        geometry.normals.append( om.MVector(  normal_value, normal_value, normal_value ) )
        geometry.normals.append( om.MVector(  normal_value, normal_value, -normal_value ) )

        ## Define the UVs for the cube. 
        ##
        uv_count = 14
        uv_pts = [  [ 0.375, 0.0  ],
                    [ 0.625, 0.0  ],
                    [ 0.625, 0.25 ],
                    [ 0.375, 0.25 ],
                    [ 0.625, 0.5  ],
                    [ 0.375, 0.5  ],
                    [ 0.625, 0.75 ],
                    [ 0.375, 0.75 ],
                    [ 0.625, 1.0  ],
                    [ 0.375, 1.0  ],
                    [ 0.875, 0.0  ],
                    [ 0.875, 0.25 ],
                    [ 0.125, 0.0  ],
                    [ 0.125, 0.25 ] ]
        
        ## UV Face Vertex Id. 
        ##
        num_face_connects = 24
        uv_fvid = [ 0, 1, 2, 3, 
                    3, 2, 4, 5, 
                    5, 4, 6, 7, 
                    7, 6, 8, 9, 
                    1, 10, 11, 2, 
                    12, 0, 3, 13 ]

        for i in xrange(uv_count):
            geometry.uvcoords.append_uv( uv_pts[i][0], uv_pts[i][1] )
        
        for i in xrange(num_face_connects):
            geometry.uvcoords.faceVertexIndex.append( uv_fvid[i] ) 

        ## Set up an array containing the number of vertices
        ## for each of the 6 cube faces (4 verticies per face)
        ##
        num_faces = 6
        face_counts = [ 4, 4, 4, 4, 4, 4 ]

        for i in xrange(num_faces):
            geometry.face_counts.append( face_counts[i] )

        ## Set up and array to assign vertices from vertices to each face 
        ##
        face_connects = [ 0, 1, 2, 3,
                          4, 5, 6, 7,
                          3, 2, 6, 5,
                          0, 3, 5, 4,
                          0, 4, 7, 1,
                          1, 7, 6, 2 ]

        for i in xrange(num_face_connects):
            geometry.face_connects.append( face_connects[i] )

    def buildSphere(self, radius, divisions, geometry):
        ##
        ## Description
        ##
        ##    Create circles of vertices starting with 
        ##    the top pole ending with the botton pole
        ##

        geometry.vertices.clear()
        geometry.normals.clear()
        geometry.face_counts.clear()
        geometry.face_connects.clear()
        geometry.uvcoords.reset()

        u = -math.pi / 2.
        v = -math.pi
        u_delta = math.pi / divisions
        v_delta = 2 * math.pi / divisions

        topPole = om.MPoint( 0.0, radius, 0.0 )
        botPole = om.MPoint( 0.0, -radius, 0.0 )

        ## Build the vertex and normal table
        ##
        geometry.vertices.append( botPole )
        geometry.normals.append( botPole - om.MPoint.kOrigin )

        for i in xrange(divisions-1):
            u += u_delta
            v = -math.pi

            for j in xrange(divisions):
                x = radius * math.cos(u) * math.cos(v)
                y = radius * math.sin(u)
                z = radius * math.cos(u) * math.sin(v)

                pnt = om.MPoint( x, y, z )
                geometry.vertices.append( pnt )
                geometry.normals.append( pnt - om.MPoint.kOrigin )
                v += v_delta

        geometry.vertices.append( topPole )
        geometry.normals.append( topPole - om.MPoint.kOrigin )

        ## Create the connectivity lists
        ##
        vid = 1
        numV = 0
        for i in xrange(divisions):
            for j in xrange(divisions):
                if i == 0:
                    geometry.face_counts.append( 3 )

                    geometry.face_connects.append( 0 )
                    geometry.face_connects.append( j + vid )
                    if j == divisions-1:
                        geometry.face_connects.append( vid )
                    else:
                        geometry.face_connects.append( j + vid + 1 )

                elif i == divisions-1:
                    geometry.face_counts.append( 3 )

                    geometry.face_connects.append( j + vid + 1 - divisions )
                    geometry.face_connects.append( vid + 1 )
                    if j == divisions-1:
                        geometry.face_connects.append( vid + 1 - divisions )
                    else:
                        geometry.face_connects.append( j + vid + 2 - divisions )

                else:
                    geometry.face_counts.append( 4 )

                    geometry.face_connects.append( j + vid + 1 - divisions )
                    geometry.face_connects.append( j + vid + 1 )
                    if j == divisions-1:
                        geometry.face_connects.append( vid + 1 )
                        geometry.face_connects.append( vid + 1 - divisions )
                    else:
                        geometry.face_connects.append( j + vid + 2 )
                        geometry.face_connects.append( j + vid + 2 - divisions )

                numV += 1

            vid = numV

## Helper class for link lost callback
class ShadedItemUserData(om.MUserData):
    def __init__(self, override):
        om.MUserData.__init__(self, False)
        self.fOverride = override

## Custom user data class to attach to face selection render item
## to help with viewport 2.0 selection
class apiMeshHWSelectionUserData(om.MUserData):
    def __init__(self):
        om.MUserData.__init__(self, True)   ## let Maya clean up
        self.fMeshGeom = None

################################################################################
##
## apiMeshSubSceneOverride
##
## Handles vertex data preparation for drawing the user defined shape in
## Viewport 2.0.
##
################################################################################
## Custom component converter to select components
## Attached to the vertex, edge and face selection render items
## respectively apiMeshSubSceneOverride.sVertexSelectionName, apiMeshSubSceneOverride.sEdgeSelectionName
## and apiMeshSubSceneOverride.sFaceSelectionName
class simpleComponentConverter_subsceneOverride(omr.MPxComponentConverter):
    def __init__(self, componentType, selectionType):
        omr.MPxComponentConverter.__init__(self)

        self.fComponentType = componentType
        self.fSelectionType = selectionType

        self.fComponent = om.MFnSingleIndexedComponent()
        self.fComponentObject = om.MObject.kNullObj
        self.fLookupTable = []

    def initialize(self, renderItem):
        ## Create the component selection object
        self.fComponentObject = self.fComponent.create( self.fComponentType )

        ## For face selection, 
        ## create a lookup table to match triangle intersection with face id :
        ## One face may contains more than one triangle
        if self.fComponentType == om.MFn.kMeshPolygonComponent:
            selectionData = renderItem.customData()
            if isinstance(selectionData, apiMeshHWSelectionUserData):
                meshGeom = selectionData.fMeshGeom

                ## Allocate faces lookup table
                numTriangles = 0
                for i in xrange(meshGeom.faceCount):
                    numVerts = meshGeom.face_counts[i]
                    if numVerts > 2:
                        numTriangles += numVerts - 2
                self.fLookupTable = [0]*numTriangles

                ## Fill faces lookup table
                triId = 0
                for faceId in xrange(meshGeom.faceCount):
                    ## ignore degenerate faces
                    numVerts = meshGeom.face_counts[faceId]
                    if numVerts > 2:
                        for v in xrange(1, numVerts-1):
                            self.fLookupTable[triId] = faceId
                            triId += 1

    def addIntersection(self, intersection):
        ## Convert the intersection index, which represent the primitive position in the
        ## index buffer, to the correct component id

        ## For vertex and edge: the primitive index value is the same as the component id
        ## For face: get the face id that matches the triangle index from the lookup table

        if self.fComponentType == om.MFn.kMeshEdgeComponent:
            # Only accept edge selection intersection on draw instance #2 -- scaled by 2
            # and instance #-1 (when useDrawInstancingOnEdgeSelectionItem is False)
            if intersection.instanceID == 1 or intersection.instanceID == 3:
                return

        idx = intersection.index

        if self.fComponentType == om.MFn.kMeshPolygonComponent:
            if idx >= 0 and idx < len(self.fLookupTable):
                idx = self.fLookupTable[idx]

        self.fComponent.addElement(idx)

    def component(self):
        ## Return the component object that contains the ids of the selected components
        return self.fComponentObject

    def selectionMask(self):
        ## This converter is only valid for specified selection type
        return self.fSelectionType

    ## creator function to instanciate a component converter for vertex selection
    @staticmethod
    def creatorVertexSelection():
        mask = om.MSelectionMask(om.MSelectionMask.kSelectMeshVerts)
        mask.addMask(om.MSelectionMask.kSelectPointsForGravity)
        return simpleComponentConverter_subsceneOverride(om.MFn.kMeshVertComponent, mask)

    ## creator function to instanciate a component converter for edge selection
    @staticmethod
    def creatorEdgeSelection():
        return simpleComponentConverter_subsceneOverride(om.MFn.kMeshEdgeComponent, om.MSelectionMask.kSelectMeshEdges)

    ## creator function to instanciate a component converter for face selection
    @staticmethod
    def creatorFaceSelection():
        return simpleComponentConverter_subsceneOverride(om.MFn.kMeshPolygonComponent, om.MSelectionMask.kSelectMeshFaces)

class apiMeshSubSceneOverride(omr.MPxSubSceneOverride):
    sWireName        = "apiMeshWire"
    sSelectName      = "apiMeshSelection"
    sBoxName         = "apiMeshBox"
    sSelectedBoxName = "apiMeshBoxSelection"
    sShadedName      = "apiMeshShaded"
    sTexturedName    = "apiMeshTextured"

    sVertexSelectionName = "apiMeshVertexSelection"
    sEdgeSelectionName   = "apiMeshEdgeSelection"
    sFaceSelectionName   = "apiMeshFaceSelection"

    sActiveVertexName = "apiMeshActiveVertex"
    sActiveEdgeName   = "apiMeshActiveEdge"
    sActiveFaceName   = "apiMeshActiveFace"

    class InstanceInfo:
        def __init__(self, transform, isSelected):
            self.fTransform = transform
            self.fIsSelected = isSelected

    @staticmethod
    def creator(obj):
        return apiMeshSubSceneOverride(obj)

    @staticmethod
    def shadedItemLinkLost(userData):
        if not userData is None and not userData.fOverride is None:
            if not userData.fOverride.fMesh is None:
                userData.fOverride.fMesh.setMaterialDirty(True)
            userData.fOverride = None
        userData = None

    def __init__(self, obj):
        omr.MPxSubSceneOverride.__init__(self, obj)
        
        node = om.MFnDependencyNode(obj)
        self.fMesh = node.userNode()
        self.fObject = om.MObject(obj)
        self.fWireShader = None
        self.fThickWireShader = None
        self.fSelectShader = None
        self.fThickSelectShader = None
        self.fShadedShader = None
        self.fVertexComponentShader = None
        self.fEdgeComponentShader = None
        self.fFaceComponentShader = None
        self.fPositionBuffer = None
        self.fNormalBuffer = None
        self.fBoxPositionBuffer = None
        self.fWireIndexBuffer = None
        self.fBoxIndexBuffer = None
        self.fShadedIndexBuffer = None
        self.fActiveVerticesIndexBuffer = None
        self.fActiveEdgesIndexBuffer = None
        self.fActiveFacesIndexBuffer = None
        self.fThickLineWidth = -1.0
        self.fQueuedLineWidth = -1.0
        self.fNumInstances = 0
        self.fIsInstanceMode = False
        self.fQueueUpdate = False
        self.fUseQueuedLineUpdate = False ## Set to True to run sample line width update code

        self.fInstanceInfoCache = collections.defaultdict(set)

        self.fActiveVerticesSet = set()
        self.fActiveEdgesSet = set()
        self.fActiveFacesSet = set()

    def __del__(self):
        self.fMesh = None

        shaderMgr = omr.MRenderer.getShaderManager()
        if shaderMgr:
            if self.fWireShader:
                shaderMgr.releaseShader(self.fWireShader)
                self.fWireShader = None

            if self.fThickWireShader:
                shaderMgr.releaseShader(self.fThickWireShader)
                self.fThickWireShader = None

            if self.fSelectShader:
                shaderMgr.releaseShader(self.fSelectShader)
                self.fSelectShader = None

            if self.fThickSelectShader:
                shaderMgr.releaseShader(self.fThickSelectShader)
                self.fThickSelectShader = None

            if self.fShadedShader:
                shaderMgr.releaseShader(self.fShadedShader)
                self.fShadedShader = None

            if self.fVertexComponentShader:
                shaderMgr.releaseShader(self.fVertexComponentShader)
                self.fVertexComponentShader = None

            if self.fEdgeComponentShader:
                shaderMgr.releaseShader(self.fEdgeComponentShader)
                self.fEdgeComponentShader = None

            if self.fFaceComponentShader:
                shaderMgr.releaseShader(self.fFaceComponentShader)
                self.fFaceComponentShader = None

        self.clearBuffers()

    def supportedDrawAPIs(self):
        ## this plugin supports both GL and DX
        return omr.MRenderer.kOpenGL | omr.MRenderer.kDirectX11 | omr.MRenderer.kOpenGLCoreProfile

    def requiresUpdate(self, container, frameContext):
        # Nothing in the container, definitely need to update
        if len(container) == 0:
            return True

        # Update always. This could be optimized to only update when the
        # actual shape node detects a change.
        return True

    def update(self, container, frameContext):
        # Update render items based on current set of instances
        self.manageRenderItems(container, frameContext, self.fMesh.shapeDirty() or len(container) == 0)

        # Always reset shape dirty flag
        self.fMesh.resetShapeDirty()

    def furtherUpdateRequired(self, frameContext):
        if self.fUseQueuedLineUpdate:
            if not frameContext.inUserInteraction() and not frameContext.userChangingViewContext():
                return self.fQueueUpdate

        return False

    def manageRenderItems(self, container, frameContext, updateGeometry):
        ## Preamble
        if not self.fMesh or self.fObject.isNull():
            return

        shaderMgr = omr.MRenderer.getShaderManager()
        if not shaderMgr:
            return

        node = om.MFnDagNode(self.fObject)
        instances = node.getAllPaths()
        if len(instances) == 0:
            return

        ## Constants
        sRed     = [1.0, 0.0, 0.0, 1.0]
        sGreen   = [0.0, 1.0, 0.0, 1.0]
        sWhite   = [1.0, 1.0, 1.0, 1.0]

        ## Set up shared shaders if needed
        if not self.fWireShader:
            self.fWireShader = shaderMgr.getStockShader(omr.MShaderManager.k3dSolidShader)
            self.fWireShader.setParameter("solidColor", sRed)

        if not self.fThickWireShader:
            self.fThickWireShader = shaderMgr.getStockShader(omr.MShaderManager.k3dThickLineShader)
            self.fThickWireShader.setParameter("solidColor", sRed)

        if not self.fSelectShader:
            self.fSelectShader = shaderMgr.getStockShader(omr.MShaderManager.k3dSolidShader)
            self.fSelectShader.setParameter("solidColor", sGreen)

        if not self.fThickSelectShader:
            self.fThickSelectShader = shaderMgr.getStockShader(omr.MShaderManager.k3dThickLineShader)
            self.fThickSelectShader.setParameter("solidColor", sGreen)

        if not self.fVertexComponentShader:
            self.fVertexComponentShader = shaderMgr.getStockShader(omr.MShaderManager.k3dFatPointShader)
            self.fVertexComponentShader.setParameter("solidColor", sWhite)
            self.fVertexComponentShader.setParameter("pointSize", [5.0, 5.0])

        if not self.fEdgeComponentShader:
            self.fEdgeComponentShader = shaderMgr.getStockShader(omr.MShaderManager.k3dThickLineShader)
            self.fEdgeComponentShader.setParameter("solidColor", sWhite)
            self.fEdgeComponentShader.setParameter("lineWidth", [2.0, 2.0])

        if not self.fFaceComponentShader:
            self.fFaceComponentShader = shaderMgr.getStockShader(omr.MShaderManager.k3dSolidShader)
            self.fFaceComponentShader.setParameter("solidColor", sWhite)

        if not self.fShadedShader:
            self.fShadedShader = shaderMgr.getStockShader(omr.MShaderManager.k3dBlinnShader)

        ## Set up shared geometry if necessary
        if updateGeometry:
            self.rebuildGeometryBuffers()

        if not all((self.fPositionBuffer, self.fNormalBuffer, self.fBoxPositionBuffer, self.fWireIndexBuffer, self.fBoxIndexBuffer, self.fShadedIndexBuffer)):
            print "At least one buffer is not set"
            return

        selectedList = om.MGlobal.getActiveSelectionList()

        anyMatrixChanged = False
        itemsChanged = False
        instanceArrayLength = len(instances)
        numInstanceSelected = 0
        numInstanceUnselected = 0
        numInstances = 0

        instanceMatrixArray = om.MMatrixArray(instanceArrayLength)
        selectedInstanceMatrixArray = om.MMatrixArray(instanceArrayLength)
        unselectedInstanceMatrixArray = om.MMatrixArray(instanceArrayLength)

        for instance in instances:
            ## If expecting large numbers of instances, then walking through the whole
            ## list of instances every time to look for changes is not efficient
            ## enough.  Watching for change events and changing only the required
            ## instances should be done instead.  This method of checking for selection
            ## status is also not fast.
            if not instance.isValid or not instance.isVisible:
                continue

            instanceNum = instance.instanceNumber()

            instanceInfo = apiMeshSubSceneOverride.InstanceInfo(instance.inclusiveMatrix(), useSelectHighlight(selectedList, instance))

            if instanceNum not in self.fInstanceInfoCache or self.fInstanceInfoCache[instanceNum].fIsSelected != instanceInfo.fIsSelected or not self.fInstanceInfoCache[instanceNum].fTransform.isEquivalent(instanceInfo.fTransform):
                self.fInstanceInfoCache[instanceNum] = instanceInfo
                anyMatrixChanged = True

            instanceMatrixArray[numInstances] = instanceInfo.fTransform
            numInstances += 1
            if instanceInfo.fIsSelected:
                selectedInstanceMatrixArray[numInstanceSelected] = instanceInfo.fTransform
                numInstanceSelected += 1
            else:
                unselectedInstanceMatrixArray[numInstanceUnselected] = instanceInfo.fTransform
                numInstanceUnselected += 1

        instanceMatrixArray.setLength(numInstances)  ## collapse to correct length
        selectedInstanceMatrixArray.setLength(numInstanceSelected)
        unselectedInstanceMatrixArray.setLength(numInstanceUnselected)
        if self.fNumInstances != numInstances:
            anyMatrixChanged = True
            self.fNumInstances = numInstances

        anyInstanceSelected = numInstanceSelected > 0
        anyInstanceUnselected = numInstanceUnselected > 0

        activeVerticesSet = set()
        activeEdgesSet = set()
        activeFacesSet = set()

        meshGeom = self.fMesh.meshGeom()
        if meshGeom and self.fMesh.hasActiveComponents():
            activeComponents = self.fMesh.activeComponents()
            if len(activeComponents) > 0:
                fnComponent = om.MFnSingleIndexedComponent( activeComponents[0] )
                if fnComponent.elementCount > 0:
                    activeIds = fnComponent.getElements()

                    if fnComponent.componentType == om.MFn.kMeshVertComponent:
                        activeVerticesSet = set(activeIds)

                    elif fnComponent.componentType == om.MFn.kMeshEdgeComponent:
                        activeEdgesSet = set(activeIds)

                    elif fnComponent.componentType == om.MFn.kMeshPolygonComponent:
                        activeFacesSet = set(activeIds)

        ## Update index buffer of active items if necessary
        updateActiveItems = updateGeometry or self.fActiveVerticesSet != activeVerticesSet or self.fActiveEdgesSet != activeEdgesSet or self.fActiveFacesSet != activeFacesSet
        self.fActiveVerticesSet = activeVerticesSet
        self.fActiveEdgesSet = activeEdgesSet
        self.fActiveFacesSet = activeFacesSet

        if updateActiveItems:
            self.rebuildActiveComponentIndexBuffers()

        anyVertexSelected = bool(self.fActiveVerticesSet)
        anyEdgeSelected = bool(self.fActiveEdgesSet)
        anyFaceSelected = bool(self.fActiveFacesSet)

        if (anyVertexSelected and not self.fActiveVerticesIndexBuffer) or (anyEdgeSelected and not self.fActiveEdgesIndexBuffer) or (anyFaceSelected and not self.fActiveFacesIndexBuffer):
            return

        ## Add render items if necessary.  Remove any pre-existing render items
        ## that are no longer needed.
        wireItem = container.find(self.sWireName)
        if not wireItem and anyInstanceUnselected:
            wireItem = omr.MRenderItem.create( self.sWireName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            wireItem.setDrawMode(omr.MGeometry.kWireframe)
            wireItem.setDepthPriority(omr.MRenderItem.sActiveWireDepthPriority)
            wireItem.setShader(self.fWireShader)
            container.add(wireItem)
            itemsChanged = True

        elif wireItem and not anyInstanceUnselected:
            container.remove(self.sWireName)
            wireItem = None
            itemsChanged = True

        selectItem = container.find(self.sSelectName)
        if not selectItem and anyInstanceSelected:
            selectItem = omr.MRenderItem.create( self.sSelectName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            selectItem.setDrawMode(omr.MGeometry.kWireframe | omr.MGeometry.kShaded | omr.MGeometry.kTextured)
            selectItem.setDepthPriority(omr.MRenderItem.sActiveWireDepthPriority)
            selectItem.setShader(self.fSelectShader)
            container.add(selectItem)
            itemsChanged = True

        elif selectItem and not anyInstanceSelected:
            container.remove(self.sSelectName)
            selectItem = None
            itemsChanged = True

        boxItem = container.find(self.sBoxName)
        if not boxItem and anyInstanceUnselected:
            boxItem = omr.MRenderItem.create( self.sBoxName, omr.MRenderItem.NonMaterialSceneItem, omr.MGeometry.kLines)
            boxItem.setDrawMode(omr.MGeometry.kBoundingBox)
            boxItem.setShader(self.fWireShader)
            container.add(boxItem)
            itemsChanged = True

        elif boxItem and not anyInstanceUnselected:
            container.remove(self.sBoxName)
            boxItem = None
            itemsChanged = True

        selectedBoxItem = container.find(self.sSelectedBoxName)
        if not selectedBoxItem and anyInstanceSelected:
            selectedBoxItem = omr.MRenderItem.create( self.sSelectedBoxName, omr.MRenderItem.NonMaterialSceneItem, omr.MGeometry.kLines)
            selectedBoxItem.setDrawMode(omr.MGeometry.kBoundingBox)
            selectedBoxItem.setShader(self.fSelectShader)
            container.add(selectedBoxItem)
            itemsChanged = True

        elif selectedBoxItem and not anyInstanceSelected:
            container.remove(self.sSelectedBoxName)
            selectedBoxItem = None
            itemsChanged = True

        shadedItem = container.find(self.sShadedName)
        if not shadedItem:
            ## We always want a shaded item
            shadedItem = omr.MRenderItem.create( self.sShadedName, omr.MRenderItem.MaterialSceneItem, omr.MGeometry.kTriangles)
            shadedItem.setDrawMode(omr.MGeometry.kShaded)
            shadedItem.setExcludedFromPostEffects(False)
            shadedItem.setCastsShadows(True)
            shadedItem.setReceivesShadows(True)
            container.add(shadedItem)
            itemsChanged = True

        texturedItem = container.find(self.sTexturedName)
        if not texturedItem:
            ## We always want a textured item
            texturedItem = omr.MRenderItem.create( self.sTexturedName, omr.MRenderItem.MaterialSceneItem, omr.MGeometry.kTriangles)
            texturedItem.setDrawMode(omr.MGeometry.kTextured)
            texturedItem.setExcludedFromPostEffects(False)
            texturedItem.setCastsShadows(True)
            texturedItem.setReceivesShadows(True)
            container.add(texturedItem)
            itemsChanged = True

        ## Grab shading node from first component of first instance of the
        ## object and use it to get an MShaderInstance. This could be expanded
        ## to support full instancing and components if necessary.
        try:
            connectedPlugs = om.MPlugArray()
            (sets, comps) = node.getConnectedSetsAndMembers(0, True)
            for obj in sets:
                dn = om.MFnDependencyNode(obj)
                shaderPlug = dn.findPlug("surfaceShader", True)
                connectedPlugs = shaderPlug.connectedTo(True, False)
                if len(connectedPlugs) > 0:
                    break;

            ## Update shader for shaded item
            if self.fMesh.materialDirty() or not shadedItem.isShaderFromNode():
                if len(connectedPlugs) == 0 or \
                   not shadedItem.setShaderFromNode(connectedPlugs[0].node(),
                                                    instances[0],
                                                    apiMeshSubSceneOverride.shadedItemLinkLost,
                                                    ShadedItemUserData(self),
                                                    True):
                    shadedItem.setShader(self.fShadedShader)

            ## Update shader for textured item
            if self.fMesh.materialDirty() or not texturedItem.isShaderFromNode():
                if len(connectedPlugs) == 0 or \
                   not texturedItem.setShaderFromNode(connectedPlugs[0].node(),
                                                      instances[0],
                                                      apiMeshSubSceneOverride.shadedItemLinkLost,
                                                      ShadedItemUserData(self),
                                                      False):
                    texturedItem.setShader(self.fShadedShader)

            ## Reset the dirty flag since shader has been set for both shaded
            ## item and textured item.
            self.fMesh.setMaterialDirty(False)
        except:
            pass

        # render item for vertex selection
        vertexSelectionItem = container.find(self.sVertexSelectionName)
        if not vertexSelectionItem:
            vertexSelectionItem = omr.MRenderItem.create( self.sVertexSelectionName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)
            # use for selection only : not visible in viewport
            vertexSelectionItem.setDrawMode(omr.MGeometry.kSelectionOnly)
            # set the selection mask to kSelectMeshVerts : we want the render item to be used for Vertex Components selection
            mask = om.MSelectionMask(om.MSelectionMask.kSelectMeshVerts)
            mask.addMask(om.MSelectionMask.kSelectPointsForGravity)
            vertexSelectionItem.setSelectionMask( mask )
            # set selection priority : on top
            vertexSelectionItem.setDepthPriority(omr.MRenderItem.sSelectionDepthPriority)
            vertexSelectionItem.setShader(self.fVertexComponentShader)
            container.add(vertexSelectionItem)
            itemsChanged = True

        # change this value to enable item instancing : same item will be rendered multiple times
        # the edge selection item will be visible in the viewport and rendered 3 times (with different scaling)
        # only the second instance (scale 1.5) will be selectable (see simpleComponentConverter_subsceneOverride)
        useDrawInstancingOnEdgeSelectionItem = False

        # render item for edge selection
        edgeSelectionItem = container.find(self.sEdgeSelectionName)
        if not edgeSelectionItem:
            # use for selection only : not visible in viewport
            drawMode = omr.MGeometry.kSelectionOnly
            depthPriority = omr.MRenderItem.sSelectionDepthPriority
            if useDrawInstancingOnEdgeSelectionItem:
                # display in viewport and in selection
                drawMode = omr.MGeometry.kAll
                # reduce priority so we can see the active item
                depthPriority = omr.MRenderItem.sActiveWireDepthPriority-1

            edgeSelectionItem = omr.MRenderItem.create( self.sEdgeSelectionName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            edgeSelectionItem.setDrawMode(drawMode)
            # set selection priority : on top
            edgeSelectionItem.setDepthPriority(depthPriority)
            # set the selection mask to kSelectMeshEdges : we want the render item to be used for Edge Components selection
            edgeSelectionItem.setSelectionMask( om.MSelectionMask.kSelectMeshEdges )
            edgeSelectionItem.setShader(self.fWireShader)
            container.add(edgeSelectionItem)
            itemsChanged = True

        # render item for face selection - not visible in viewport
        faceSelectionItem = container.find(self.sFaceSelectionName)
        if not faceSelectionItem:
            faceSelectionItem = omr.MRenderItem.create( self.sFaceSelectionName, omr.MRenderItem.DecorationItem, omr.MGeometry.kTriangles)
            # use for selection only : not visible in viewport
            faceSelectionItem.setDrawMode(omr.MGeometry.kSelectionOnly)
            # set the selection mask to kSelectMeshFaces : we want the render item to be used for Face Components selection
            faceSelectionItem.setSelectionMask( om.MSelectionMask.kSelectMeshFaces )
            # set selection priority : on top
            faceSelectionItem.setDepthPriority(omr.MRenderItem.sSelectionDepthPriority)
            faceSelectionItem.setShader(self.fFaceComponentShader)
            container.add(faceSelectionItem)
            itemsChanged = True

        ## create and add a custom data to help the face component converter
        if updateGeometry:
            mySelectionData = apiMeshHWSelectionUserData()
            mySelectionData.fMeshGeom = self.fMesh.meshGeom()
            faceSelectionItem.setCustomData(mySelectionData)

        # render item to display active (selected) vertices
        activeVertexItem = container.find(self.sActiveVertexName)
        if not activeVertexItem and anyVertexSelected:
            activeVertexItem = omr.MRenderItem.create( self.sActiveVertexName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)
            activeVertexItem.setDrawMode(omr.MGeometry.kAll)
            activeVertexItem.setDepthPriority(omr.MRenderItem.sActivePointDepthPriority)
            activeVertexItem.setShader(self.fVertexComponentShader)
            container.add(activeVertexItem)
            itemsChanged = True

        elif activeVertexItem and not anyVertexSelected:
            container.remove(self.sActiveVertexName)
            activeVertexItem = None
            itemsChanged = True

        # render item to display active (selected) edges
        activeEdgeItem = container.find(self.sActiveEdgeName)
        if not activeEdgeItem and anyEdgeSelected:
            activeEdgeItem = omr.MRenderItem.create( self.sActiveEdgeName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            activeEdgeItem.setDrawMode(omr.MGeometry.kAll)
            activeEdgeItem.setDepthPriority(omr.MRenderItem.sActiveLineDepthPriority)
            activeEdgeItem.setShader(self.fEdgeComponentShader)
            container.add(activeEdgeItem)
            itemsChanged = True

        elif activeEdgeItem and not anyEdgeSelected:
            container.remove(self.sActiveEdgeName)
            activeEdgeItem = None
            itemsChanged = True

        # render item to display active (selected) faces
        activeFaceItem = container.find(self.sActiveFaceName)
        if not activeFaceItem and anyFaceSelected:
            activeFaceItem = omr.MRenderItem.create( self.sActiveFaceName, omr.MRenderItem.DecorationItem, omr.MGeometry.kTriangles)
            activeFaceItem.setDrawMode(omr.MGeometry.kAll)
            activeFaceItem.setDepthPriority(omr.MRenderItem.sActiveLineDepthPriority)
            activeFaceItem.setShader(self.fFaceComponentShader)
            container.add(activeFaceItem)
            itemsChanged = True

        elif activeFaceItem and not anyFaceSelected:
            container.remove(self.sActiveFaceName)
            activeFaceItem = None
            itemsChanged = True

        ## update the line width on the shader for our wire items if it changed
        lineWidth = frameContext.getGlobalLineWidth()
        userWidthChange = not floatApproxEqual(lineWidth, self.fThickLineWidth)

        doUpdate = False
        targetRefinedLineWidth = 50.0
        if userWidthChange:
            self.fThickLineWidth = lineWidth
            doUpdate = True

            ## First user change will trigger an update requirement
            if self.fUseQueuedLineUpdate:
                self.fQueuedLineWidth = lineWidth
                if self.fQueuedLineWidth < targetRefinedLineWidth:
                    self.fQueueUpdate = True

        else:
            ## Increment by 1 until we reach the target width.
            ## If we haven't reached it yet then queue another update
            ## so we can increment and retest against the target width.
            if self.fUseQueuedLineUpdate and self.fQueueUpdate:
                if self.fQueuedLineWidth < targetRefinedLineWidth:
                    lineWidth = self.fQueuedLineWidth
                    self.fQueuedLineWidth += 1
                    self.fQueueUpdate = True
                    doUpdate = True

                else:
                    ## Reached target. Stop asking for more refinement
                    self.fQueueUpdate = False
        
        if doUpdate:
            if not floatApproxEqual(lineWidth, 1.0):
                ## Only set the shader if the line width changes (or the first time)
                lineWidthArray = [ lineWidth, lineWidth ]
                self.fThickWireShader.setParameter("lineWidth", lineWidthArray)
                self.fThickSelectShader.setParameter("lineWidth", lineWidthArray)
                if wireItem:
                    wireItem.setShader(self.fThickWireShader)
                if selectItem:
                    selectItem.setShader(self.fThickSelectShader)

            else:
                if wireItem:
                    wireItem.setShader(self.fWireShader)
                if selectItem:
                    selectItem.setShader(self.fSelectShader)

        ## Update geometry if required
        if itemsChanged or updateGeometry:
            bounds = self.fMesh.boundingBox()

            wireBuffers = omr.MVertexBufferArray()
            wireBuffers.append(self.fPositionBuffer, "positions")
            if wireItem:
                self.setGeometryForRenderItem(wireItem, wireBuffers, self.fWireIndexBuffer, bounds)
            if selectItem:
                self.setGeometryForRenderItem(selectItem, wireBuffers, self.fWireIndexBuffer, bounds)

            boxBuffers = omr.MVertexBufferArray()
            boxBuffers.append(self.fBoxPositionBuffer, "positions")
            if boxItem:
                self.setGeometryForRenderItem(boxItem, boxBuffers, self.fBoxIndexBuffer, bounds)
            if selectedBoxItem:
                self.setGeometryForRenderItem(selectedBoxItem, boxBuffers, self.fBoxIndexBuffer, bounds)

            shadedBuffers = omr.MVertexBufferArray()
            shadedBuffers.append(self.fPositionBuffer, "positions")
            shadedBuffers.append(self.fNormalBuffer, "normals")
            self.setGeometryForRenderItem(shadedItem, shadedBuffers, self.fShadedIndexBuffer, bounds)
            self.setGeometryForRenderItem(texturedItem, shadedBuffers, self.fShadedIndexBuffer, bounds)

            # The vertexSelectionItem has a sequential index buffer, use non-indexed draw:
            self.setGeometryForRenderItem(vertexSelectionItem, wireBuffers, objectBox = bounds)
            self.setGeometryForRenderItem(edgeSelectionItem, wireBuffers, self.fWireIndexBuffer, bounds)
            self.setGeometryForRenderItem(faceSelectionItem, wireBuffers, self.fShadedIndexBuffer, bounds)

        ## Update active component items if required
        if itemsChanged or updateActiveItems:
            bounds = self.fMesh.boundingBox()

            vertexBuffer = omr.MVertexBufferArray()
            vertexBuffer.append(self.fPositionBuffer, "positions")

            if activeVertexItem:
                self.setGeometryForRenderItem(activeVertexItem, vertexBuffer, self.fActiveVerticesIndexBuffer, bounds)
            if activeEdgeItem:
                self.setGeometryForRenderItem(activeEdgeItem, vertexBuffer, self.fActiveEdgesIndexBuffer, bounds)
            if activeFaceItem:
                self.setGeometryForRenderItem(activeFaceItem, vertexBuffer, self.fActiveFacesIndexBuffer, bounds)

        ## Update render item matrices if necessary
        if itemsChanged or anyMatrixChanged:
            if not self.fIsInstanceMode and numInstances == 1:
                ## When not dealing with multiple instances, don't convert the render items into instanced
                ## mode.  Set the matrices on them directly.
                objToWorld = instanceMatrixArray[0]

                if wireItem:
                    wireItem.setMatrix(objToWorld)
                if selectItem:
                    selectItem.setMatrix(objToWorld)
                if boxItem:
                    boxItem.setMatrix(objToWorld)
                if selectedBoxItem:
                    selectedBoxItem.setMatrix(objToWorld)
                shadedItem.setMatrix(objToWorld)
                texturedItem.setMatrix(objToWorld)

                vertexSelectionItem.setMatrix(objToWorld)
                edgeSelectionItem.setMatrix(objToWorld)
                faceSelectionItem.setMatrix(objToWorld)

                if useDrawInstancingOnEdgeSelectionItem:
                    ## create/update draw instances
                    ## first instance : no scaling - won't be selectable see simpleComponentConverter_subsceneOverride.addIntersection
                    transform1 = objToWorld
                    transform1[15] = 1  # make sure we don't scale the w
                    ## second instance : scaled by 2
                    transform2 = objToWorld * 2
                    transform2[15] = 1  # make sure we don't scale the w
                    ## third instance : scaled by 3 - won't be selectable see simpleComponentConverter_subsceneOverride.addIntersection
                    transform3 = objToWorld * 3
                    transform3[15] = 1  # make sure we don't scale the w

                    if True:
                        transforms = om.MMatrixArray((transform1, transform2, transform3))
                        self.setInstanceTransformArray(edgeSelectionItem, transforms)
                    else:
                        ## another way to set up the instances
                        ## useful to get the instance ID
                        try:
                            self.removeAllInstances(edgeSelectionItem)
                        except:
                            # removeAllInstances raise an error if the item is not set up for instancing
                            pass
                        newInstanceId = self.addInstanceTransform(edgeSelectionItem, transform1)
                        print "newInstanceId " + str(newInstanceId)
                        newInstanceId = self.addInstanceTransform(edgeSelectionItem, transform2)
                        print "newInstanceId " + str(newInstanceId)
                        newInstanceId = self.addInstanceTransform(edgeSelectionItem, transform3)
                        print "newInstanceId " + str(newInstanceId)

                if activeVertexItem:
                    activeVertexItem.setMatrix(objToWorld)
                if activeEdgeItem:
                    activeEdgeItem.setMatrix(objToWorld)
                if activeFaceItem:
                    activeFaceItem.setMatrix(objToWorld)

            else:
                ## If we have DAG instances of this shape then use the MPxSubSceneOverride instance
                ## transform API to set up instance copies of the render items.  This will be faster
                ## to render than creating render items for each instance, especially for large numbers
                ## of instances.
                ## Note: for simplicity, this code is not tracking the actual shaded material binding
                ## of the shape.  MPxSubSceneOverride render item instances require that the shader
                ## and other properties of the instances all match.  So if we were to bind a shader based
                ## on the DAG shape material binding, then we would need one render item per material. We
                ## could then group up the instance transforms based matching materials.

                ## Note this has to happen after the geometry and shaders are set, otherwise it will fail.
                if wireItem:
                    self.setInstanceTransformArray(wireItem, unselectedInstanceMatrixArray)
                if selectItem:
                    self.setInstanceTransformArray(selectItem, selectedInstanceMatrixArray)
                if boxItem:
                    self.setInstanceTransformArray(boxItem, unselectedInstanceMatrixArray)
                if selectedBoxItem:
                    self.setInstanceTransformArray(selectedBoxItem, selectedInstanceMatrixArray)
                self.setInstanceTransformArray(shadedItem, instanceMatrixArray)
                self.setInstanceTransformArray(texturedItem, instanceMatrixArray)

                self.setInstanceTransformArray(vertexSelectionItem, instanceMatrixArray)
                self.setInstanceTransformArray(edgeSelectionItem, instanceMatrixArray)
                self.setInstanceTransformArray(faceSelectionItem, instanceMatrixArray)

                if activeVertexItem:
                    self.setInstanceTransformArray(activeVertexItem, instanceMatrixArray)
                if activeEdgeItem:
                    self.setInstanceTransformArray(activeEdgeItem, instanceMatrixArray)
                if activeFaceItem:
                    self.setInstanceTransformArray(activeFaceItem, instanceMatrixArray)

                ## Once we change the render items into instance rendering they can't be changed back without
                ## being deleted and re-created.  So if instances are deleted to leave only one remaining,
                ## just keep treating them the instance way.
                self.fIsInstanceMode = True

        if itemsChanged or anyMatrixChanged or updateGeometry:
            ## On transform or geometry change, force recalculation of shadow maps
            omr.MRenderer.setLightsAndShadowsDirty()

    def rebuildGeometryBuffers(self):
        ## Preamble
        meshGeom = self.fMesh.meshGeom()
        if not meshGeom:
            return
        bounds = self.fMesh.boundingBox()

        ## Clear old
        self.clearGeometryBuffers()

        ## Compute mesh data size
        numTriangles = 0
        totalVerts = 0
        totalPoints = len(meshGeom.vertices)
        for i in xrange(meshGeom.faceCount):
            numVerts = meshGeom.face_counts[i]
            if numVerts > 2:
                numTriangles += numVerts - 2
                totalVerts += numVerts

        ## Acquire vertex buffer resources
        posDesc = omr.MVertexBufferDescriptor("", omr.MGeometry.kPosition, omr.MGeometry.kFloat, 3)
        normalDesc = omr.MVertexBufferDescriptor("", omr.MGeometry.kNormal, omr.MGeometry.kFloat, 3)

        self.fPositionBuffer = omr.MVertexBuffer(posDesc)
        self.fNormalBuffer = omr.MVertexBuffer(normalDesc)
        self.fBoxPositionBuffer = omr.MVertexBuffer(posDesc)

        positionDataAddress = self.fPositionBuffer.acquire(totalPoints, True)
        normalDataAddress = self.fNormalBuffer.acquire(totalPoints, True)
        boxPositionDataAddress = self.fBoxPositionBuffer.acquire(8, True)

        ## Acquire index buffer resources
        self.fWireIndexBuffer = omr.MIndexBuffer(omr.MGeometry.kUnsignedInt32)
        self.fBoxIndexBuffer = omr.MIndexBuffer(omr.MGeometry.kUnsignedInt32)
        self.fShadedIndexBuffer = omr.MIndexBuffer(omr.MGeometry.kUnsignedInt32)

        wireBufferDataAddress = self.fWireIndexBuffer.acquire(2*totalVerts, True)
        boxBufferDataAddress = self.fBoxIndexBuffer.acquire(24, True)
        shadedBufferDataAddress = self.fShadedIndexBuffer.acquire(3*numTriangles, True)

        ## Sanity check
        if not all((positionDataAddress, normalDataAddress, boxPositionDataAddress, wireBufferDataAddress, boxBufferDataAddress, shadedBufferDataAddress)):
            print "At least one buffer data is not valid"
            self.clearGeometryBuffers()
            return

        positionData = ((ctypes.c_float * 3)*totalPoints).from_address(positionDataAddress)
        normalData = ((ctypes.c_float * 3)*totalPoints).from_address(normalDataAddress)
        boxPositionData = ((ctypes.c_float * 3)*8).from_address(boxPositionDataAddress)

        wireBufferData = (ctypes.c_uint * (2*totalVerts)).from_address(wireBufferDataAddress)
        boxBufferData = (ctypes.c_uint * 24).from_address(boxBufferDataAddress)
        shadedBufferData = ((ctypes.c_uint * 3)*numTriangles).from_address(shadedBufferDataAddress)

        ## Fill vertex data for shaded/wireframe
        for vid,position in enumerate(meshGeom.vertices):
            positionData[vid][0] = position[0]
            positionData[vid][1] = position[1]
            positionData[vid][2] = position[2]

        for vid,normal in enumerate(meshGeom.normals):
            normalData[vid][0] = normal[0]
            normalData[vid][1] = normal[1]
            normalData[vid][2] = normal[2]

        self.fPositionBuffer.commit(positionDataAddress)
        positionDataAddress = None
        self.fNormalBuffer.commit(normalDataAddress)
        normalDataAddress = None

        ## Fill vertex data for bounding box
        bbmin = bounds.min
        bbmax = bounds.max
        boxPositionData[0][0] = bbmin.x
        boxPositionData[0][1] = bbmin.y
        boxPositionData[0][2] = bbmin.z

        boxPositionData[1][0] = bbmin.x
        boxPositionData[1][1] = bbmin.y
        boxPositionData[1][2] = bbmax.z

        boxPositionData[2][0] = bbmax.x
        boxPositionData[2][1] = bbmin.y
        boxPositionData[2][2] = bbmax.z

        boxPositionData[3][0] = bbmax.x
        boxPositionData[3][1] = bbmin.y
        boxPositionData[3][2] = bbmin.z

        boxPositionData[4][0] = bbmin.x
        boxPositionData[4][1] = bbmax.y
        boxPositionData[4][2] = bbmin.z

        boxPositionData[5][0] = bbmin.x
        boxPositionData[5][1] = bbmax.y
        boxPositionData[5][2] = bbmax.z

        boxPositionData[6][0] = bbmax.x
        boxPositionData[6][1] = bbmax.y
        boxPositionData[6][2] = bbmax.z

        boxPositionData[7][0] = bbmax.x
        boxPositionData[7][1] = bbmax.y
        boxPositionData[7][2] = bbmin.z

        self.fBoxPositionBuffer.commit(boxPositionDataAddress)
        boxPositionDataAddress = None

        ## Fill index data for wireframe
        vid = 0
        first = 0
        idx = 0
        for i in xrange(meshGeom.faceCount):
            ## Ignore degenerate faces
            numVerts = meshGeom.face_counts[i]
            if numVerts > 2:
                first = vid
                for v in xrange(numVerts-1):
                    wireBufferData[idx] = meshGeom.face_connects[vid]
                    idx += 1
                    vid += 1
                    wireBufferData[idx] = meshGeom.face_connects[vid]
                    idx += 1

                wireBufferData[idx] = meshGeom.face_connects[vid]
                idx += 1
                vid += 1
                wireBufferData[idx] = meshGeom.face_connects[first]
                idx += 1

            else:
                vid += numVerts

        self.fWireIndexBuffer.commit(wireBufferDataAddress)
        wireBufferDataAddress = None

        ## Fill index data for bounding box
        indexData = [ 0, 1, 1, 2, 2, 3, 3, 0, 4, 5, 5, 6, 6, 7, 7, 4, 0, 4, 1, 5, 2, 6, 3, 7 ]
        for i in xrange(24):
            boxBufferData[i] = indexData[i]

        self.fBoxIndexBuffer.commit(boxBufferDataAddress)
        boxBufferDataAddress = None

        ## Fill index data for shaded
        base = 0
        idx = 0
        for i in xrange(meshGeom.faceCount):
            ## Ignore degenerate faces
            numVerts = meshGeom.face_counts[i]
            if numVerts > 2:
                for v in xrange(1, numVerts-1):
                    shadedBufferData[idx][0] = meshGeom.face_connects[base]
                    shadedBufferData[idx][1] = meshGeom.face_connects[base+v]
                    shadedBufferData[idx][2] = meshGeom.face_connects[base+v+1]
                    idx += 1

                base += numVerts
        
        self.fShadedIndexBuffer.commit(shadedBufferDataAddress)
        shadedBufferDataAddress = None

    def rebuildActiveComponentIndexBuffers(self):
        ## Preamble
        meshGeom = self.fMesh.meshGeom()
        if not meshGeom:
            return

        ## Clear old
        self.clearActiveComponentIndexBuffers()

        ## Acquire and fill index buffer for active vertices
        numActiveVertices = len(self.fActiveVerticesSet)
        if numActiveVertices > 0:
            self.fActiveVerticesIndexBuffer = omr.MIndexBuffer(omr.MGeometry.kUnsignedInt32)
            activeVerticesDataAddress = self.fActiveVerticesIndexBuffer.acquire(numActiveVertices, True)
            if activeVerticesDataAddress:
                activeVerticesData = (ctypes.c_uint*numActiveVertices).from_address(activeVerticesDataAddress)

                idx = 0
                for vid in self.fActiveVerticesSet:
                    activeVerticesData[idx] = vid 
                    idx += 1

                self.fActiveVerticesIndexBuffer.commit(activeVerticesDataAddress)
                activeVerticesDataAddress = None

        ## Acquire and fill index buffer for active edges
        numActiveEdges = len(self.fActiveEdgesSet)
        if numActiveEdges > 0:
            self.fActiveEdgesIndexBuffer = omr.MIndexBuffer(omr.MGeometry.kUnsignedInt32)
            activeEdgesDataAddress = self.fActiveEdgesIndexBuffer.acquire(2*numActiveEdges, True)
            if activeEdgesDataAddress:
                activeEdgesData = ((ctypes.c_uint * 2)*numActiveEdges).from_address(activeEdgesDataAddress)

                eid = 0
                first = 0
                vid = 0
                idx = 0
                for i in xrange(meshGeom.faceCount):
                    ## Ignore degenerate faces
                    numVerts = meshGeom.face_counts[i]
                    if numVerts > 2:
                        first = vid
                        for v in xrange(numVerts-1):
                            if eid in self.fActiveEdgesSet:
                                activeEdgesData[idx][0] = meshGeom.face_connects[vid]
                                activeEdgesData[idx][1] = meshGeom.face_connects[vid + 1]
                                idx += 1
                            vid += 1
                            eid += 1

                        if eid in self.fActiveEdgesSet:
                            activeEdgesData[idx][0] = meshGeom.face_connects[vid]
                            activeEdgesData[idx][1] = meshGeom.face_connects[first]
                            idx += 1
                        vid += 1
                        eid += 1
                    else:
                        vid += numVerts

                self.fActiveEdgesIndexBuffer.commit(activeEdgesDataAddress)
                activeEdgesDataAddress = None

        ## Acquire and fill index buffer for active faces
        numActiveFaces = len(self.fActiveFacesSet)
        if numActiveFaces > 0:
            numActiveFacesTriangles = 0
            for i in xrange(meshGeom.faceCount):
                if i in self.fActiveFacesSet:
                    numVerts = meshGeom.face_counts[i]
                    if numVerts > 2:
                        numActiveFacesTriangles += numVerts - 2

            self.fActiveFacesIndexBuffer = omr.MIndexBuffer(omr.MGeometry.kUnsignedInt32)
            activeFacesDataAddress = self.fActiveFacesIndexBuffer.acquire(3*numActiveFacesTriangles, True)
            if activeFacesDataAddress:
                activeFacesData = ((ctypes.c_uint * 3)*numActiveFacesTriangles).from_address(activeFacesDataAddress)

                idx = 0
                vid = 0
                for i in xrange(meshGeom.faceCount):
                    numVerts = meshGeom.face_counts[i]
                    if numVerts > 2:
                        if i in self.fActiveFacesSet:
                            for v in xrange(1, numVerts-1):
                                activeFacesData[idx][0] = meshGeom.face_connects[vid]
                                activeFacesData[idx][1] = meshGeom.face_connects[vid+v]
                                activeFacesData[idx][2] = meshGeom.face_connects[vid+v+1]
                                idx += 1

                        vid += numVerts

                self.fActiveFacesIndexBuffer.commit(activeFacesDataAddress)
                activeFacesDataAddress = None

    def clearBuffers(self):
        self.clearGeometryBuffers()
        self.clearActiveComponentIndexBuffers()

    def clearGeometryBuffers(self):
        self.fPositionBuffer = None
        self.fNormalBuffer = None
        self.fBoxPositionBuffer = None
        self.fWireIndexBuffer = None
        self.fBoxIndexBuffer = None
        self.fShadedIndexBuffer = None

    def clearActiveComponentIndexBuffers(self):
        self.fActiveVerticesIndexBuffer = None
        self.fActiveEdgesIndexBuffer = None
        self.fActiveFacesIndexBuffer = None

    def updateSelectionGranularity(self, path, selectionContext):
        ## This is method is called during the pre-filtering phase of the viewport 2.0 selection
        ## and is used to setup the selection context of the given DAG object.

        ## We want the whole shape to be selectable, so we set the selection level to kObject so that the shape
        ## will be processed by the selection.

        ## In case we are currently in component selection mode (vertex, edge or face),
        ## since we have created render items that can be use in the selection phase (kSelectionOnly draw mode)
        ## and we also registered component converters to handle this render items,
        ## we can set the selection level to kComponent so that the shape will also be processed by the selection.
        displayStatus = omr.MGeometryUtilities.displayStatus(path)
        if displayStatus == omr.MGeometryUtilities.kHilite:
    
            globalComponentMask = om.MGlobal.objectSelectionMask()
            if om.MGlobal.selectionMode() == om.MGlobal.kSelectComponentMode:
                globalComponentMask = om.MGlobal.componentSelectionMask()

            supportedComponentMask = om.MSelectionMask( om.MSelectionMask.kSelectMeshVerts )
            supportedComponentMask.addMask( om.MSelectionMask.kSelectMeshEdges )
            supportedComponentMask.addMask( om.MSelectionMask.kSelectMeshFaces )
            supportedComponentMask.addMask( om.MSelectionMask.kSelectPointsForGravity )
            
            if globalComponentMask.intersects(supportedComponentMask):
                selectionContext.selectionLevel = omr.MSelectionContext.kComponent
        elif omr.MPxSubSceneOverride.pointSnappingActive():
            selectionContext.selectionLevel = omr.MSelectionContext.kComponent


################################################################################
##
## apiMeshGeometryOverride
##
## Handles vertex data preparation for drawing the user defined shape in
## Viewport 2.0.
##
################################################################################
## Custom user data class to attach to render items
class apiMeshUserData(om.MUserData):
    def __init__(self):
        om.MUserData.__init__(self, True)   ## let Maya clean up
        self.fMessage = ""
        self.fNumModifications = 0

## Pre/Post callback helper
def callbackDataPrint(context, renderItemList):
    for item in renderItemList:
        if item:
            path = item.sourceDagPath()
            print "\tITEM: '" + item.name() + "' -- SOURCE: '" + path.fullPathName() + "'"

    passCtx = context.getPassContext()
    passId = passCtx.passIdentifier()
    passSem = passCtx.passSemantics()
    print "\tAPI mesh drawing in pass[" + passId + "], semantic[" + passSem + "]"

## Custom pre-draw callback
def apiMeshPreDrawCallback(context, renderItemList, shaderInstance):
    print "PRE-draw callback triggered for render item list with data:"
    callbackDataPrint(context, renderItemList)

## Custom post-draw callback
def apiMeshPostDrawCallback(context, renderItemList, shaderInstance):
    print "POST-draw callback triggered for render item list with data:"
    callbackDataPrint(context, renderItemList)

## Custom component converter to select vertices
## Attached to the dormant vertices render item (apiMeshGeometryOverride.sVertexItemName)
class meshVertComponentConverter_geometryOverride(omr.MPxComponentConverter):
    def __init__(self):
        omr.MPxComponentConverter.__init__(self)

        self.fComponent = om.MFnSingleIndexedComponent()
        self.fComponentObject = om.MObject.kNullObj
        self.fVertices = []

    def initialize(self, renderItem):
        ## Create the component selection object .. here we are selecting vertex component
        self.fComponentObject = self.fComponent.create( om.MFn.kMeshVertComponent )

        ## Build a lookup table to match each primitive position in the index buffer of the render item geometry
        ## to the correponding vertex component of the object
        ## Use same algorithm as in apiMeshGeometryOverride.updateIndexingForDormantVertices

        selectionData = renderItem.customData()
        if isinstance(selectionData, apiMeshHWSelectionUserData):
            meshGeom = selectionData.fMeshGeom

            ## Allocate vertices lookup table
            numTriangles = 0
            for i in xrange(meshGeom.faceCount):
                numVerts = meshGeom.face_counts[i]
                if numVerts > 2:
                    numTriangles += numVerts - 2
            self.fVertices = [0]*(3*numTriangles)

            ## Fill vertices lookup table
            base = 0
            idx = 0
            for faceIdx in xrange(meshGeom.faceCount):
                ## ignore degenerate faces
                numVerts = meshGeom.face_counts[faceIdx]
                if numVerts > 2:
                    for v in xrange(1, numVerts-1):
                        self.fVertices[idx] = meshGeom.face_connects[base]
                        self.fVertices[idx+1] = meshGeom.face_connects[base+v]
                        self.fVertices[idx+2] = meshGeom.face_connects[base+v+1]
                        idx += 3
                    base += numVerts

    def addIntersection(self, intersection):
        ## Convert the intersection index, which represent the primitive position in the
        ## index buffer, to the correct vertex component
        rawIdx = intersection.index
        idx = 0
        if rawIdx >= 0 and rawIdx < len(self.fVertices):
            idx = self.fVertices[rawIdx]
        self.fComponent.addElement(idx)

    def component(self):
        ## Return the component object that contains the ids of the selected vertices
        return self.fComponentObject

    def selectionMask(self):
        ## This converter is only valid for vertex selection
        mask = om.MSelectionMask(om.MSelectionMask.kSelectMeshVerts)
        mask.addMask(om.MSelectionMask.kSelectPointsForGravity)
        return mask

    @staticmethod
    def creator():
        return meshVertComponentConverter_geometryOverride()

## Custom component converter to select edges
## Attached to the edge selection render item (apiMeshGeometryOverride.sEdgeSelectionItemName)
class meshEdgeComponentConverter_geometryOverride(omr.MPxComponentConverter):
    def __init__(self):
        omr.MPxComponentConverter.__init__(self)

        self.fComponent = om.MFnSingleIndexedComponent()
        self.fComponentObject = om.MObject.kNullObj
        self.fEdges = []

    def initialize(self, renderItem):
        ## Create the component selection object .. here we are selecting edge component
        self.fComponentObject = self.fComponent.create( om.MFn.kMeshEdgeComponent )

        ## Build a lookup table to match each primitive position in the index buffer of the render item geometry
        ## to the correponding edge component of the object
        ## Use same algorithm as in apiMeshGeometryOverride.updateIndexingForEdges

        ## in updateIndexingForEdges the index buffer is allocated with "totalEdges = 2*totalVerts"
        ## but since we are drawing lines, we'll get only half of the data as primitive positions :
        ## indices 0 & 1 : primitive #0
        ## indices 2 & 3 : primitive #1
        ## ...

        selectionData = renderItem.customData()
        if isinstance(selectionData, apiMeshHWSelectionUserData):
            meshGeom = selectionData.fMeshGeom

            ## Allocate edges lookup table
            totalVerts = 0
            for i in xrange(meshGeom.faceCount):
                numVerts = meshGeom.face_counts[i]
                if numVerts > 2:
                    totalVerts += numVerts
            self.fEdges = [0]*(totalVerts)

            ## Fill edges lookup table
            idx = 0
            edgeId = 0
            for faceIdx in xrange(meshGeom.faceCount):
                ## ignore degenerate faces
                numVerts = meshGeom.face_counts[faceIdx]
                if numVerts > 2:
                    for v in xrange(numVerts):
                        self.fEdges[idx] = edgeId
                        edgeId += 1
                        idx += 1

    def addIntersection(self, intersection):
        ## Convert the intersection index, which represent the primitive position in the
        ## index buffer, to the correct edge component
        rawIdx = intersection.index
        idx = 0
        if rawIdx >= 0 and rawIdx < len(self.fEdges):
            idx = self.fEdges[rawIdx]
        self.fComponent.addElement(idx)

    def component(self):
        ## Return the component object that contains the ids of the selected edges
        return self.fComponentObject

    def selectionMask(self):
        ## This converter is only valid for edge selection
        return om.MSelectionMask(om.MSelectionMask.kSelectMeshEdges)

    @staticmethod
    def creator():
        return meshEdgeComponentConverter_geometryOverride()

## Custom component converter to select faces
## Attached to the face selection render item (apiMeshGeometryOverride.sFaceSelectionItemName)
class meshFaceComponentConverter_geometryOverride(omr.MPxComponentConverter):
    def __init__(self):
        omr.MPxComponentConverter.__init__(self)

        self.fComponent = om.MFnSingleIndexedComponent()
        self.fComponentObject = om.MObject.kNullObj
        self.fFaces = []

    def initialize(self, renderItem):
        ## Create the component selection object .. here we are selecting face component
        self.fComponentObject = self.fComponent.create( om.MFn.kMeshPolygonComponent )

        ## Build a lookup table to match each primitive position in the index buffer of the render item geometry
        ## to the correponding face component of the object
        ## Use same algorithm as in apiMeshGeometryOverride.updateIndexingForFaces

        ## in updateIndexingForFaces the index buffer is allocated with "numTriangleVertices = 3*numTriangles"
        ## but since we are drawing triangles, we'll get only a third of the data as primitive positions :
        ## indices 0, 1 & 2 : primitive #0
        ## indices 3, 4 & 5 : primitive #1
        ## ...

        selectionData = renderItem.customData()
        if isinstance(selectionData, apiMeshHWSelectionUserData):
            meshGeom = selectionData.fMeshGeom

            ## Allocate faces lookup table
            numTriangles = 0
            for i in xrange(meshGeom.faceCount):
                numVerts = meshGeom.face_counts[i]
                if numVerts > 2:
                    numTriangles += numVerts - 2
            self.fFaces = [0]*numTriangles

            ## Fill faces lookup table
            idx = 0
            for faceIdx in xrange(meshGeom.faceCount):
                ## ignore degenerate faces
                numVerts = meshGeom.face_counts[faceIdx]
                if numVerts > 2:
                    for v in xrange(1, numVerts-1):
                        self.fFaces[idx] = faceIdx
                        idx += 1

    def addIntersection(self, intersection):
        ## Convert the intersection index, which represent the primitive position in the
        ## index buffer, to the correct face component
        rawIdx = intersection.index
        idx = 0
        if rawIdx >= 0 and rawIdx < len(self.fFaces):
            idx = self.fFaces[rawIdx]
        self.fComponent.addElement(idx)

    def component(self):
        ## Return the component object that contains the ids of the selected faces
        return self.fComponentObject

    def selectionMask(self):
        ## This converter is only valid for face selection
        return om.MSelectionMask(om.MSelectionMask.kSelectMeshFaces)

    @staticmethod
    def creator():
        return meshFaceComponentConverter_geometryOverride()

class apiMeshGeometryOverride(omr.MPxGeometryOverride):
    ## Render item names
    sWireframeItemName = "apiMeshWire"
    sShadedTemplateItemName = "apiMeshShadedTemplateWire"
    sSelectedWireframeItemName = "apiMeshSelectedWireFrame"
    sVertexItemName = "apiMeshVertices"
    sEdgeSelectionItemName = "apiMeshEdgeSelection"
    sFaceSelectionItemName = "apiMeshFaceSelection"
    sActiveVertexItemName = "apiMeshActiveVertices"
    sVertexIdItemName = "apiMeshVertexIds"
    sVertexPositionItemName = "apiMeshVertexPositions"
    sShadedModeFaceCenterItemName = "apiMeshFaceCenterInShadedMode"
    sWireframeModeFaceCenterItemName = "apiMeshFaceCenterInWireframeMode"
    sShadedProxyItemName = "apiShadedProxy"
    sAffectedEdgeItemName = "apiMeshAffectedEdges"
    sAffectedFaceItemName = "apiMeshAffectedFaces"
    sActiveVertexStreamName = "apiMeshSharedVertexStream"
    sFaceCenterStreamName = "apiMeshFaceCenterStream"

    @staticmethod
    def creator(obj):
        return apiMeshGeometryOverride(obj)

    def __init__(self, obj):
        omr.MPxGeometryOverride.__init__(self, obj)

        node = om.MFnDependencyNode(obj)
        self.fMesh = node.userNode()
        self.fMeshGeom = None
        self.fColorRemapTexture = None

        self.fActiveVertices = om.MIntArray()
        self.fActiveVerticesSet = set()
        self.fActiveEdgesSet = set()
        self.fActiveFacesSet = set()
        self.fCastsShadows = False
        self.fReceivesShadows = False

        ## Stream names used for filling in different data
        ## for different streams required for different render items,
        ## and toggle to choose whether to use name streams
        ##
        self.fDrawSharedActiveVertices = True
        ## Turn on to view active vertices with colours lookedup from a 1D texture.
        self.fDrawActiveVerticesWithRamp = False
        self.fLinearSampler = None

        ##Vertex stream for face centers which is calculated from faces.
        self.fDrawFaceCenters = True

        if self.fDrawActiveVerticesWithRamp:
            self.fDrawFaceCenters = False   ## Too cluttered showing the face centers at the same time.

        ## Can set the following to True, but then the logic to
        ## determine what color to set is the responsibility of the plugin.
        ##
        self.fUseCustomColors = False

        ## Can change this to choose a different shader to use when
        ## no shader node is assigned to the object.
        ## self.fProxyShader = omr.MShaderManager.k3dSolidShader ## - Basic line shader
        ## self.fProxyShader = omr.MShaderManager.k3dStippleShader ## - For filled stipple faces (triangles)
        ## self.fProxyShader = omr.MShaderManager.k3dThickLineShader ## For thick solid colored lines
        ## self.fProxyShader = omr.MShaderManager.k3dCPVThickLineShader ## For thick colored lines. Black if no CPV
        ## self.fProxyShader = omr.MShaderManager.k3dDashLineShader ## - For dashed solid color lines
        ## self.fProxyShader = omr.MShaderManager.k3dCPVDashLineShader ##- For dashed coloured lines. Black if no CPV
        ## self.fProxyShader = omr.MShaderManager.k3dThickDashLineShader ## For thick dashed solid color lines. black if no cpv
        self.fProxyShader = omr.MShaderManager.k3dCPVThickDashLineShader ##- For thick, dashed and coloured lines

        ## Set to True to test that overriding internal items has no effect
        ## for shadows and effects overrides
        self.fInternalItems_NoShadowCast = False
        self.fInternalItems_NoShadowReceive = False
        self.fInternalItems_NoPostEffects = False

        ## Use the existing shadow casts / receives flags on the shape
        ## to drive settings for applicable render items.
        self.fExternalItems_NoShadowCast = False
        self.fExternalItems_NoShadowReceive = False
        self.fExternalItemsNonTri_NoShadowCast = False
        self.fExternalItemsNonTri_NoShadowReceive = False

        ## Set to True to ignore post-effects for wireframe items.
        ## Shaded items will still have effects applied.
        self.fExternalItems_NoPostEffects = True
        self.fExternalItemsNonTri_NoPostEffects = True

    def __del__(self):
        self.fMesh = None
        self.fMeshGeom = None

        if self.fColorRemapTexture:
            textureMgr = omr.MRenderer.getTextureManager()
            if textureMgr:
                textureMgr.releaseTexture(self.fColorRemapTexture)
            self.fColorRemapTexture = None

        if self.fLinearSampler:
            omr.MStateManager.releaseSamplerState(self.fLinearSampler)
            self.fLinearSampler = None

    def supportedDrawAPIs(self):
        ## this plugin supports both GL and DX
        return omr.MRenderer.kOpenGL | omr.MRenderer.kDirectX11 | omr.MRenderer.kOpenGLCoreProfile

    def updateDG(self):
        ## Pull the actual outMesh from the shape, as well
        ## as any active components
        self.fActiveVertices.clear()
        self.fActiveVerticesSet = set()
        self.fActiveEdgesSet = set()
        self.fActiveFacesSet = set()
        if self.fMesh:
            self.fMeshGeom = self.fMesh.meshGeom()

            if self.fMeshGeom and self.fMesh.hasActiveComponents():
                activeComponents = self.fMesh.activeComponents()
                if len(activeComponents) > 0:
                    fnComponent = om.MFnSingleIndexedComponent( activeComponents[0] )
                    if fnComponent.elementCount > 0:
                        activeIds = fnComponent.getElements()

                        if fnComponent.componentType == om.MFn.kMeshVertComponent:
                            self.fActiveVertices = activeIds
                            self.fActiveVerticesSet = set(activeIds)

                        elif fnComponent.componentType == om.MFn.kMeshEdgeComponent:
                            self.fActiveEdgesSet = set(activeIds)

                        elif fnComponent.componentType == om.MFn.kMeshPolygonComponent:
                            self.fActiveFacesSet = set(activeIds)

    def updateRenderItems(self, path, list):
        ## Update render items. Shaded render item is provided so this
        ## method will be adding and updating UI render items only.

        shaderMgr = omr.MRenderer.getShaderManager()
        if not shaderMgr:
            return

        dagNode = om.MFnDagNode(path)
        castsShadowsPlug = dagNode.findPlug("castsShadows", False)
        self.fCastsShadows = castsShadowsPlug.asBool()
        receiveShadowsPlug = dagNode.findPlug("receiveShadows", False)
        self.fReceivesShadows = receiveShadowsPlug.asBool()

        ##1 Update wireframe render items
        self.updateDormantAndTemplateWireframeItems(path, list, shaderMgr)
        self.updateActiveWireframeItem(path, list, shaderMgr)

        ## Update vertex render items
        self.updateDormantVerticesItem(path, list, shaderMgr)
        self.updateActiveVerticesItem(path, list, shaderMgr)

        ## Update vertex numeric render items
        self.updateVertexNumericItems(path, list, shaderMgr)

        ## Update face center item
        if self.fDrawFaceCenters:
            self.updateWireframeModeFaceCenterItem(path, list, shaderMgr)
            self.updateShadedModeFaceCenterItem(path, list, shaderMgr)

        ## Update "affected" edge and face render items
        self.updateAffectedComponentItems(path, list, shaderMgr)

        ## Update faces and edges selection items
        self.updateSelectionComponentItems(path, list, shaderMgr)

        ## Update proxy shaded render item
        self.updateProxyShadedItem(path, list, shaderMgr)

        ## Test overrides on existing shaded items.
        ## In this case it is not valid to override these states
        ## so there should be no change in behaviour.
        ##
        testShadedOverrides = self.fInternalItems_NoShadowCast or self.fInternalItems_NoShadowReceive or self.fInternalItems_NoPostEffects
        if testShadedOverrides:
            for item in list:
                if not item:
                    continue

                drawMode = item.drawMode()
                if drawMode == omr.MGeometry.kShaded or drawMode == omr.MGeometry.kTextured:
                    if item.name() != self.sShadedTemplateItemName:
                        item.setCastsShadows( not self.fInternalItems_NoShadowCast and self.fCastsShadows )
                        item.setReceivesShadows( not self.fInternalItems_NoShadowReceive and self.fReceivesShadows )
                        item.setExcludedFromPostEffects( self.fInternalItems_NoPostEffects )

    def populateGeometry(self, requirements, renderItems, data):
        ## Fill in data and index streams based on the requirements passed in.
        ## Associate indexing with the render items passed in.
        ## 
        ## Note that we leave both code paths to either draw shared or non-shared active vertices.
        ## The choice of which to use is up to the circumstances per plug-in.
        ## When drawing shared vertices, this requires an additional position buffer to be
        ## created so will use more memory. If drawing unshared vertices redundent extra
        ## vertices are drawn but will use less memory. The data member fDrawSharedActiveVertices
        ## can be set to decide on which implementation to use.
    
        debugPopulateGeometry = False
        if debugPopulateGeometry:
            print "> Begin populate geometry"

        ## Get the active vertex count
        activeVertexCount = len(self.fActiveVertices)

        ## Compute the number of triangles, assume polys are always convex
        numTriangles = 0
        totalVerts = 0
        for i in xrange(self.fMeshGeom.faceCount):
            numVerts = self.fMeshGeom.face_counts[i]
            if numVerts > 2:
                numTriangles += numVerts - 2
                totalVerts += numVerts

        ## Update data streams based on geometry requirements
        self.updateGeometryRequirements(requirements, data, activeVertexCount, totalVerts, debugPopulateGeometry)

        ## Update indexing data for all appropriate render items
        wireIndexBuffer = None ## reuse same index buffer for both wireframe and selected

        for item in renderItems:
            if not item:
                continue

            ## Enable to debug vertex buffers that are associated with each render item.
            ## Can also use to generate indexing better, but we don't need that here.
            ## Also debugs custom data on the render item.
            debugStuff = False
            if debugStuff:
                itemBuffers = item.requiredVertexBuffers()
                for desc in itemBuffers:
                    print "Buffer Required for Item '" + item.name() + "':"
                    print "\tBufferName: " + desc.name
                    print "\tDataType: " + omr.MGeometry.dataTypeString(desc.dataType) + " (dimension " + str(desc.dimension) + ")"
                    print "\tSemantic: " + omr.MGeometry.semanticString(desc.semantic)
                    print ""

                ## Just print a message for illustration purposes. Note that the custom data is also
                ## accessible from the MRenderItem in MPxShaderOverride::draw().
                myCustomData = item.customData()
                if isinstance(myCustomData, apiMeshUserData):
                    print "Custom data '" + myCustomData.fMessage + "', modified count='" + str(myCustomData.fNumModifications) + "'"
                else:
                    print "No custom data"

            ## Update indexing for active vertex item
            ##
            if item.name() == self.sActiveVertexItemName:
                self.updateIndexingForVertices( item, data, numTriangles, activeVertexCount, debugPopulateGeometry)

            ## Update indexing for face center item in wireframe mode and shaded mode
            ##
            if self.fDrawFaceCenters and (item.name() == self.sShadedModeFaceCenterItemName or item.name() == self.sWireframeModeFaceCenterItemName):
                self.updateIndexingForFaceCenters( item, data, debugPopulateGeometry)

            ## Create indexing for dormant and numeric vertex render items
            ##
            elif item.name() == self.sVertexItemName or item.name() == self.sVertexIdItemName or item.name() == self.sVertexPositionItemName:
                self.updateIndexingForDormantVertices( item, data, numTriangles )

            ## Create indexing for wireframe render items
            ##
            elif item.name() == self.sWireframeItemName or item.name() == self.sShadedTemplateItemName or item.name() == self.sSelectedWireframeItemName or (item.primitive() != omr.MGeometry.kTriangles and item.name() == self.sShadedProxyItemName):
                self.updateIndexingForWireframeItems(wireIndexBuffer, item, data, totalVerts)

            ## Handle indexing for affected edge render items
            ## For each face we check the edges. If the edges are in the active vertex
            ## list we add indexing for the 2 vertices on the edge to the index buffer.
            ##
            elif item.name() == self.sAffectedEdgeItemName:
                self.updateIndexingForEdges(item, data, totalVerts, True) ## Filter edges using active edges or actives vertices set
            elif item.name() == self.sEdgeSelectionItemName:
                self.updateIndexingForEdges(item, data, totalVerts, False) ## No filter : all edges

            ## Handle indexing for affected edge render items
            ## For each triangle we check the vertices. If any of the vertices are in the active vertex
            ## list we add indexing for the triangle to the index buffer.
            ##
            elif item.name() == self.sAffectedFaceItemName:
                self.updateIndexingForFaces(item, data, numTriangles, True) ## Filter faces using active faces or actives vertices set
            elif item.name() == self.sFaceSelectionItemName:
                self.updateIndexingForFaces(item, data, numTriangles, False) ## No filter : all faces

            ## Create indexing for filled (shaded) render items
            ##
            elif item.primitive() == omr.MGeometry.kTriangles:
                self.updateIndexingForShadedTriangles(item, data, numTriangles)

        if debugPopulateGeometry:
            print "> End populate geometry"

    def cleanUp(self):
        self.fMeshGeom = None
        self.fActiveVertices.clear()
        self.fActiveVerticesSet = set()
        self.fActiveEdgesSet = set()
        self.fActiveFacesSet = set()

    def updateSelectionGranularity(self, path, selectionContext):
        ## This is method is called during the pre-filtering phase of the viewport 2.0 selection
        ## and is used to setup the selection context of the given DAG object.

        ## We want the whole shape to be selectable, so we set the selection level to kObject so that the shape
        ## will be processed by the selection.

        ## In case we are currently in component selection mode (vertex, edge or face),
        ## since we have created render items that can be use in the selection phase (kSelectionOnly draw mode)
        ## and we also registered component converters to handle this render items,
        ## we can set the selection level to kComponent so that the shape will also be processed by the selection.

        displayStatus = omr.MGeometryUtilities.displayStatus(path)
        if displayStatus == omr.MGeometryUtilities.kHilite:
    
            globalComponentMask = om.MGlobal.objectSelectionMask()
            if om.MGlobal.selectionMode() == om.MGlobal.kSelectComponentMode:
                globalComponentMask = om.MGlobal.componentSelectionMask()

            supportedComponentMask = om.MSelectionMask( om.MSelectionMask.kSelectMeshVerts )
            supportedComponentMask.addMask( om.MSelectionMask.kSelectMeshEdges )
            supportedComponentMask.addMask( om.MSelectionMask.kSelectMeshFaces )
            supportedComponentMask.addMask( om.MSelectionMask.kSelectPointsForGravity )
            
            if globalComponentMask.intersects(supportedComponentMask):
                selectionContext.selectionLevel = omr.MSelectionContext.kComponent
        elif omr.MPxGeometryOverride.pointSnappingActive():
            selectionContext.selectionLevel = omr.MSelectionContext.kComponent

    def printShader(self, shader):
        ## Some example code to print out shader parameters
        if not shader:
            return

        params = shader.parameterList()
        print "DEBUGGING SHADER, BEGIN PARAM LIST OF LENGTH " + str(len(params))

        for param in params:
            paramType = shader.parameterType(param)
            isArray = shader.isArrayParameter(param)

            typeAsStr = "Unknown"
            if paramType == omr.MShaderInstance.kInvalid:
                typeAsStr = "Invalid"
            elif paramType == omr.MShaderInstance.kBoolean:
                typeAsStr = "Boolean"
            elif paramType == omr.MShaderInstance.kInteger:
                typeAsStr = "Integer"
            elif paramType == omr.MShaderInstance.kFloat:
                typeAsStr = "Float"
            elif paramType == omr.MShaderInstance.kFloat2:
                typeAsStr = "Float2"
            elif paramType == omr.MShaderInstance.kFloat3:
                typeAsStr = "Float3"
            elif paramType == omr.MShaderInstance.kFloat4:
                typeAsStr = "Float4"
            elif paramType == omr.MShaderInstance.kFloat4x4Row:
                typeAsStr = "Float4x4Row"
            elif paramType == omr.MShaderInstance.kFloat4x4Col:
                typeAsStr = "Float4x4Col"
            elif paramType == omr.MShaderInstance.kTexture1:
                typeAsStr = "1D Texture"
            elif paramType == omr.MShaderInstance.kTexture2:
                typeAsStr = "2D Texture"
            elif paramType == omr.MShaderInstance.kTexture3:
                typeAsStr = "3D Texture"
            elif paramType == omr.MShaderInstance.kTextureCube:
                typeAsStr = "Cube Texture"
            elif paramType == omr.MShaderInstance.kSampler:
                typeAsStr = "Sampler"

            print "ParamName='" + param + "', ParamType='" + typeAsStr + "', IsArrayParameter:'" + str(isArray) + "'"

        print "END PARAM LIST"

    def setSolidColor(self, shaderInstance, defaultColor, customColor=None):
        ## Set the solid color for solid color shaders
        if shaderInstance:
            color = defaultColor
            if self.fUseCustomColors and customColor:
                color = customColor
            try:
                shaderInstance.setParameter("solidColor", color)
            except:
                pass

    def setSolidPointSize(self, shaderInstance, size):
        ## Set the point size for solid color shaders
        if shaderInstance:
            try:
                shaderInstance.setParameter("pointSize", [size, size])
            except:
                pass

    def setLineWidth(self, shaderInstance, width):
        ## Set the line width for solid color shaders
        if shaderInstance:
            try:
                shaderInstance.setParameter("lineWidth", [width, width])
            except:
                pass

    def enableActiveComponentDisplay(self, path):
        ## Test to see if active components should be enabled.
        ## Based on active vertices + non-template state

        enable = True

        ## If there are components then we need to check
        ## either the display status of the object, or
        ## in the case of a templated object make sure
        ## to hide components to be consistent with how
        ## internal objects behave
        ##
        displayStatus = omr.MGeometryUtilities.displayStatus(path)
        if displayStatus == omr.MGeometryUtilities.kHilite or displayStatus == omr.MGeometryUtilities.kActiveComponent:
            enable = False
        
        else:
            ## Do an explicit path test for templated
            ## since display status does not indicate this.
            if path.isTemplated():
                enable = False

        return enable

    ## Render item handling methods
    def updateDormantAndTemplateWireframeItems(self, path, list, shaderMgr):
        ## Update render items for dormant and template wireframe drawing.
        ## 
        ## 1) If the object is dormant and not templated then we require
        ## a render item to display when wireframe drawing is required (display modes
        ## is wire or wire-on-shaded)
        ## 
        ## 2a) If the object is templated then we use the same render item as in 1)
        ## when in wireframe drawing is required.
        ## 2b) However we also require a render item to display when in shaded mode.
    
        ## Stock colors
        dormantColor = [ 0.0, 0.0, 1.0, 1.0 ]
        templateColor = [ 0.45, 0.45, 0.45, 1.0 ]
        activeTemplateColor = [ 1.0, 0.5, 0.5, 1.0 ]

        ## Some local options to show debug interface
        ##
        debugShader = False

        ## Get render item used for draw in wireframe mode
        ## (Mode to draw in is omr.MGeometry.kWireframe)
        ##
        wireframeItem = None
        index = list.indexOf(self.sWireframeItemName)
        if index < 0:
            wireframeItem = omr.MRenderItem.create( self.sWireframeItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            wireframeItem.setDrawMode(omr.MGeometry.kWireframe)

            ## Set dormant wireframe with appropriate priority to not clash with
            ## any active wireframe which may overlap in depth.
            wireframeItem.setDepthPriority( omr.MRenderItem.sDormantWireDepthPriority )

            list.append(wireframeItem)

            preCb = None
            postCb = None
            if debugShader:
                preCb = apiMeshPreDrawCallback
                postCb = apiMeshPostDrawCallback

            shader = shaderMgr.getStockShader(omr.MShaderManager.k3dSolidShader, preCb, postCb)
            if shader:
                ## assign shader
                wireframeItem.setShader(shader)

                ## sample debug code
                if debugShader:
                    self.printShader( shader )

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            wireframeItem = list[index]

        ## Get render item for handling mode shaded template drawing
        ##
        shadedTemplateItem = None
        index = list.indexOf(self.sShadedTemplateItemName)
        if index < 0:
            shadedTemplateItem = omr.MRenderItem.create( self.sShadedTemplateItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            shadedTemplateItem.setDrawMode(omr.MGeometry.kAll)

            ## Set shaded item as being dormant wire since it should still be raised
            ## above any shaded items, but not as high as active items.
            shadedTemplateItem.setDepthPriority( omr.MRenderItem.sDormantWireDepthPriority )

            list.append(shadedTemplateItem)

            shader = shaderMgr.getStockShader(omr.MShaderManager.k3dSolidShader)
            if shader:
                ## assign shader
                shadedTemplateItem.setShader(shader)

                ## sample debug code
                if debugShader:
                    self.printShader( shader )

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            shadedTemplateItem = list[index]

        ## Sample code to disable cast, receives shadows, and post effects.
        shadedTemplateItem.setCastsShadows( not self.fExternalItemsNonTri_NoShadowCast )
        shadedTemplateItem.setReceivesShadows( not self.fExternalItemsNonTri_NoShadowReceive )
        shadedTemplateItem.setExcludedFromPostEffects( self.fExternalItemsNonTri_NoPostEffects )

        displayStatus = omr.MGeometryUtilities.displayStatus(path)
        wireColor = omr.MGeometryUtilities.wireframeColor(path)

        ## Enable / disable wireframe item and update the shader parameters
        ##
        if wireframeItem:
            shader = wireframeItem.getShader()

            if displayStatus == omr.MGeometryUtilities.kTemplate:
                self.setSolidColor( shader, wireColor, templateColor)
                wireframeItem.enable(True)

            elif displayStatus == omr.MGeometryUtilities.kActiveTemplate:
                self.setSolidColor( shader, wireColor, activeTemplateColor)
                wireframeItem.enable(True)

            elif displayStatus == omr.MGeometryUtilities.kDormant:
                self.setSolidColor( shader, wireColor, dormantColor)
                wireframeItem.enable(True)

            elif displayStatus == omr.MGeometryUtilities.kActiveAffected:
                theColor = [ 0.5, 0.0, 1.0, 1.0 ]
                self.setSolidColor( shader, wireColor, theColor)
                wireframeItem.enable(True)

            else:
                wireframeItem.enable(False)

        ## Enable / disable shaded/template item and update the shader parameters
        ##
        if shadedTemplateItem:
            isTemplate = path.isTemplated()
            shader = shadedTemplateItem.getShader()

            if displayStatus == omr.MGeometryUtilities.kTemplate:
                self.setSolidColor( shader, wireColor, templateColor)
                shadedTemplateItem.enable(isTemplate)

            elif displayStatus == omr.MGeometryUtilities.kActiveTemplate:
                self.setSolidColor( shader, wireColor, activeTemplateColor)
                shadedTemplateItem.enable(isTemplate)

            elif displayStatus == omr.MGeometryUtilities.kDormant:
                self.setSolidColor( shader, wireColor, dormantColor)
                shadedTemplateItem.enable(isTemplate)

            else:
                shadedTemplateItem.enable(False)

    def updateActiveWireframeItem(self, path, list, shaderMgr):
        ## Create a render item for active wireframe if it does not exist. Updating
        ## shading parameters as necessary.

        selectItem = None
        index = list.indexOf(self.sSelectedWireframeItemName)
        if index < 0:
            selectItem = omr.MRenderItem.create(self.sSelectedWireframeItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            selectItem.setDrawMode(omr.MGeometry.kAll)
            ## This is the same as setting the argument raiseAboveShaded = True,/
            ## since it sets the priority value to be the same. This line is just
            ## an example of another way to do the same thing after creation of
            ## the render item.
            selectItem.setDepthPriority( omr.MRenderItem.sActiveWireDepthPriority )
            list.append(selectItem)

            ## For active wireframe we will use a shader which allows us to draw thick lines
            ##
            drawThick = False
            shaderId = omr.MShaderManager.k3dSolidShader
            if drawThick:
                shaderId = omr.MShaderManager.k3dThickLineShader

            shader = shaderMgr.getStockShader(shaderId)
            if shader:
                ## assign shader
                selectItem.setShader(shader)
                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            selectItem = list[index]

        shader = None
        if selectItem:
            shader = selectItem.getShader()

        displayStatus = omr.MGeometryUtilities.displayStatus(path)
        wireColor = omr.MGeometryUtilities.wireframeColor(path)

        if displayStatus == omr.MGeometryUtilities.kLead:
            theColor = [ 0.0, 0.8, 0.0, 1.0 ]
            self.setSolidColor( shader, wireColor, theColor)
            selectItem.enable(True)

        elif displayStatus == omr.MGeometryUtilities.kActive:
            theColor = [ 1.0, 1.0, 1.0, 1.0 ]
            self.setSolidColor( shader, wireColor, theColor)
            selectItem.enable(True)

        elif displayStatus == omr.MGeometryUtilities.kHilite or displayStatus == omr.MGeometryUtilities.kActiveComponent:
            theColor = [ 0.0, 0.5, 0.7, 1.0 ]
            self.setSolidColor( shader, wireColor, theColor)
            selectItem.enable(True)

        else:
            selectItem.enable(False)

        ## Add custom user data to selection item
        myCustomData = selectItem.customData()
        if not myCustomData:
            ## create the custom data
            myCustomData = apiMeshUserData()
            myCustomData.fMessage = "I'm custom data!"
            selectItem.setCustomData(myCustomData)
        else:
            ## modify the custom data
            myCustomData.fNumModifications += 1

    def updateWireframeModeFaceCenterItem(self, path, list, shaderMgr):
        ## Add render item for face centers in wireframe mode, always show face centers
        ## in wireframe mode except it is drawn as template.

        wireframeModeFaceCenterItem = None
        index = list.indexOf(self.sWireframeModeFaceCenterItemName)
        if index < 0:
            wireframeModeFaceCenterItem = omr.MRenderItem.create(self.sWireframeModeFaceCenterItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)
            wireframeModeFaceCenterItem.setDrawMode(omr.MGeometry.kWireframe)
            wireframeModeFaceCenterItem.setDepthPriority( omr.MRenderItem.sActiveWireDepthPriority )

            list.append(wireframeModeFaceCenterItem)

            shader = shaderMgr.getStockShader( omr.MShaderManager.k3dFatPointShader )
            if shader:
                ## Set the point size parameter. Make it slightly larger for face centers
                pointSize = 5.0
                self.setSolidPointSize( shader, pointSize )

                wireframeModeFaceCenterItem.setShader(shader, self.sFaceCenterStreamName )

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
            else:
                wireframeModeFaceCenterItem = list[index]

        if wireframeModeFaceCenterItem:
            shader = wireframeModeFaceCenterItem.getShader()
            if shader:
                ## Set face center color in wireframe mode
                theColor = [ 0.0, 0.0, 1.0, 1.0 ]
                self.setSolidColor( shader, theColor )

            ## disable the face center item when template
            isTemplate = path.isTemplated()
            wireframeModeFaceCenterItem.enable( not isTemplate )

    def updateShadedModeFaceCenterItem(self, path, list, shaderMgr):
        ##Add render item for face centers in shaded mode. If the geometry is not selected,
        ## face centers are not drawn.

        shadedModeFaceCenterItem = None
        index = list.indexOf(self.sShadedModeFaceCenterItemName)
        if index < 0:
            shadedModeFaceCenterItem = omr.MRenderItem.create( self.sShadedModeFaceCenterItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)
            shadedModeFaceCenterItem.setDrawMode(omr.MGeometry.kShaded | omr.MGeometry.kTextured)

            shadedModeFaceCenterItem.setDepthPriority(omr.MRenderItem.sActivePointDepthPriority)

            list.append(shadedModeFaceCenterItem)

            shader = shaderMgr.getStockShader( omr.MShaderManager.k3dFatPointShader )
            if shader:
                ## Set the point size parameter. Make it slightly larger for face centers
                pointSize = 5.0
                self.setSolidPointSize( shader, pointSize )

                shadedModeFaceCenterItem.setShader(shader, self.sFaceCenterStreamName )

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            shadedModeFaceCenterItem = list[index]

        if shadedModeFaceCenterItem:
            shadedModeFaceCenterItem.setExcludedFromPostEffects(True)

            shader = shadedModeFaceCenterItem.getShader()
            wireColor = omr.MGeometryUtilities.wireframeColor(path)

            if shader:
                ## Set face center color in shaded mode
                self.setSolidColor( shader, wireColor )

            displayStatus = omr.MGeometryUtilities.displayStatus(path)
            if displayStatus == omr.MGeometryUtilities.kActive or displayStatus == omr.MGeometryUtilities.kLead or displayStatus == omr.MGeometryUtilities.kActiveComponent or displayStatus == omr.MGeometryUtilities.kLive or displayStatus == omr.MGeometryUtilities.kHilite:
                shadedModeFaceCenterItem.enable(True)

            else:
                shadedModeFaceCenterItem.enable(False)

    def updateDormantVerticesItem(self, path, list, shaderMgr):
        ## Create a render item for dormant vertices if it does not exist. Updating
        ## shading parameters as necessary.

        vertexItem = None
        index = list.indexOf(self.sVertexItemName)
        if index < 0:
            vertexItem = omr.MRenderItem.create(self.sVertexItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)

            ## Set draw mode to kAll : the item will be visible in the viewport and also during viewport 2.0 selection
            vertexItem.setDrawMode(omr.MGeometry.kAll)

            ## Set the selection mask to kSelectMeshVerts : we want the render item to be used for Vertex Components selection
            mask = om.MSelectionMask(om.MSelectionMask.kSelectMeshVerts)
            mask.addMask(om.MSelectionMask.kSelectPointsForGravity)
            vertexItem.setSelectionMask( mask )

            ## Set depth priority higher than wireframe and shaded render items,
            ## but lower than active points.
            ## Raising higher than wireframe will make them not seem embedded into the surface
            vertexItem.setDepthPriority( omr.MRenderItem.sDormantPointDepthPriority )
            list.append(vertexItem)

            shader = shaderMgr.getStockShader( omr.MShaderManager.k3dFatPointShader )
            if shader:
                ## Set the point size parameter
                pointSize = 3.0
                self.setSolidPointSize( shader, pointSize )

                ## assign shader
                vertexItem.setShader(shader)

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            vertexItem = list[index]

        if vertexItem:
            shader = vertexItem.getShader()
            ## set color
            theColor = [ 0.0, 0.0, 1.0, 1.0 ]
            self.setSolidColor( shader, theColor )

            displayStatus = omr.MGeometryUtilities.displayStatus(path)

            ## Generally if the display status is hilite then we
            ## draw components.
            if displayStatus == omr.MGeometryUtilities.kHilite or omr.MPxGeometryOverride.pointSnappingActive():
                ## In case the object is templated
                ## we will hide the components to be consistent
                ## with how internal objects behave.
                if path.isTemplated():
                    vertexItem.enable(False)
                else:
                    vertexItem.enable(True)
            else:
                vertexItem.enable(False)

            mySelectionData = vertexItem.customData()
            if not isinstance(mySelectionData, apiMeshHWSelectionUserData):
                ## create the custom data
                mySelectionData = apiMeshHWSelectionUserData()
                vertexItem.setCustomData(mySelectionData)
            ## update the custom data
            mySelectionData.fMeshGeom = self.fMeshGeom

    def updateActiveVerticesItem(self, path, list, shaderMgr):
        ## Create a render item for active vertices if it does not exist. Updating
        ## shading parameters as necessary.

        activeItem = None
        index = list.indexOf(self.sActiveVertexItemName)
        if index < 0:
            activeItem = omr.MRenderItem.create(self.sActiveVertexItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)
            activeItem.setDrawMode(omr.MGeometry.kAll)
            ## Set depth priority to be active point. This should offset it
            ## to be visible above items with "dormant point" priority.
            activeItem.setDepthPriority( omr.MRenderItem.sActivePointDepthPriority )
            list.append(activeItem)

            shaderId = omr.MShaderManager.k3dFatPointShader
            if self.fDrawActiveVerticesWithRamp:
                shaderId = omr.MShaderManager.k3dColorLookupFatPointShader

            shader = shaderMgr.getStockShader( shaderId )
            if shader:
                ## Set the point size parameter. Make it slightly larger for active vertices
                pointSize = 5.0
                self.setSolidPointSize( shader, pointSize )

                ## 1D Ramp color lookup option
                ##
                if self.fDrawActiveVerticesWithRamp:
                    textureMgr = omr.MRenderer.getTextureManager()

                    ## Assign dummy ramp lookup
                    if not self.fColorRemapTexture:
                        ## Sample 3 colour ramp
                        colorArray = [  1.0, 0.0, 0.0, 1.0,
                                        0.0, 1.0, 0.0, 1.0,
                                        0.0, 0.0, 1.0, 1.0 ]

                        arrayLen = 3
                        textureDesc = omr.MTextureDescription()
                        textureDesc.setToDefault2DTexture()
                        textureDesc.fWidth = arrayLen
                        textureDesc.fHeight = 1
                        textureDesc.fDepth = 1
                        textureDesc.fBytesPerSlice = textureDesc.fBytesPerRow = 24*arrayLen
                        textureDesc.fMipmaps = 1
                        textureDesc.fArraySlices = 1
                        textureDesc.fTextureType = omr.MRenderer.kImage1D
                        textureDesc.fFormat = omr.MRenderer.kR32G32B32A32_FLOAT
                        self.fColorRemapTexture = textureMgr.acquireTexture("", textureDesc, colorArray, False)

                    if not self.fLinearSampler:
                        samplerDesc = omr.MSamplerStateDesc()
                        samplerDesc.addressU = omr.MSamplerState.kTexClamp
                        samplerDesc.addressV = omr.MSamplerState.kTexClamp
                        samplerDesc.addressW = omr.MSamplerState.kTexClamp
                        samplerDesc.filter = omr.MSamplerState.kMinMagMipLinear
                        fLinearSampler = omr.MStateManager.acquireSamplerState(samplerDesc)

                    if self.fColorRemapTexture and self.fLinearSampler:
                        ## Set up the ramp lookup
                        shader.setParameter("map", self.fColorRemapTexture)
                        shader.setParameter("samp", self.fLinearSampler)

                        ## No remapping. The initial data created in the xrange 0...1
                        ##
                        rampValueRange = om.MFloatVector(0.0, 1.0)
                        shader.setParameter("UVRange", rampValueRange)

                ## Assign shader. Use a named stream if we want to supply a different
                ## set of "shared" vertices for drawing active vertices
                if self.fDrawSharedActiveVertices:
                    activeItem.setShader(shader, self.sActiveVertexStreamName)
                else:
                    activeItem.setShader(shader, None)

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)

        else:
            activeItem = list[index]

        if activeItem:
            shader = activeItem.getShader()
            if shader:
                ## Set active color
                theColor = [ 1.0, 1.0, 0.0, 1.0 ]
                self.setSolidColor( shader, theColor )

            enable = (bool(self.fActiveVerticesSet) and self.enableActiveComponentDisplay(path))
            activeItem.enable( enable )

    def updateVertexNumericItems(self, path, list, shaderMgr):
        ## Create render items for numeric display, and update shaders as necessary

        ## Enable to show numeric render items
        enableNumericDisplay = False

        ## Vertex id item
        ##
        vertexItem = None
        index = list.indexOf(self.sVertexIdItemName)
        if index < 0:
            vertexItem = omr.MRenderItem.create( self.sVertexIdItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)
            vertexItem.setDrawMode(omr.MGeometry.kAll)
            vertexItem.setDepthPriority( omr.MRenderItem.sDormantPointDepthPriority )
            list.append(vertexItem)

            ## Use single integer numeric shader
            shader = shaderMgr.getStockShader( omr.MShaderManager.k3dIntegerNumericShader )
            if shader:
                ## Label the fields so that they can be found later on.
                vertexItem.setShader(shader, self.sVertexIdItemName)
                shaderMgr.releaseShader(shader)
        else:
            vertexItem = list[index]

        if vertexItem:
            shader = vertexItem.getShader()
            if shader:
                ## set color
                theColor = [ 1.0, 1.0, 0.0, 1.0 ]
                self.setSolidColor( shader, theColor )

            vertexItem.enable(enableNumericDisplay)

        ## Vertex position numeric render item
        ##
        vertexItem = None
        index = list.indexOf(self.sVertexPositionItemName)
        if index < 0:
            vertexItem = omr.MRenderItem.create( self.sVertexPositionItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kPoints)
            vertexItem.setDrawMode(omr.MGeometry.kAll)
            vertexItem.setDepthPriority( omr.MRenderItem.sDormantPointDepthPriority )
            list.append(vertexItem)

            ## Use triple float numeric shader
            shader = shaderMgr.getStockShader( omr.MShaderManager.k3dFloat3NumericShader )
            if shader:
                ##vertexItem.setShader(shader)
                vertexItem.setShader(shader, self.sVertexPositionItemName)
                shaderMgr.releaseShader(shader)
        else:
            vertexItem = list[index]

        if vertexItem:
            shader = vertexItem.getShader()
            if shader:
                ## set color
                theColor = [ 0.0, 1.0, 1.0, 1.0 ]
                self.setSolidColor( shader, theColor)

            vertexItem.enable(enableNumericDisplay)

    def updateAffectedComponentItems(self, path, list, shaderMgr):
        ## Example of adding in items to hilite edges and faces. In this
        ## case these are edges and faces which are connected to vertices
        ## and we thus call them "affected" components.

        ## Create / update "affected/active" edges component render item.
        ##
        componentItem = None
        index = list.indexOf(self.sAffectedEdgeItemName)
        if index < 0:
            componentItem = omr.MRenderItem.create( self.sAffectedEdgeItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)
            componentItem.setDrawMode(omr.MGeometry.kAll)

            ## Set depth priority to be active line so that it is above wireframe
            ## but below dormant and active points.
            componentItem.setDepthPriority( omr.MRenderItem.sActiveLineDepthPriority )
            list.append(componentItem)

            shader = shaderMgr.getStockShader( omr.MShaderManager.k3dThickLineShader )
            if shader:
                ## Set lines a bit thicker to stand out
                lineSize = 1.0
                self.setLineWidth( shader, lineSize )

                ## Assign shader.
                componentItem.setShader(shader, None)

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            componentItem = list[index]

        if componentItem:
            shader = componentItem.getShader()
            if shader:
                ## Set affected color
                theColor = [ 1.0, 1.0, 1.0, 1.0 ]
                self.setSolidColor( shader, theColor )

            enable = ((bool(self.fActiveVerticesSet) or bool(self.fActiveEdgesSet)) and self.enableActiveComponentDisplay(path))
            componentItem.enable( enable )

        ################################################################################

        ## Create / update "affected/active" faces component render item
        ##
        componentItem = None
        index = list.indexOf(self.sAffectedFaceItemName)
        if index < 0:
            componentItem = omr.MRenderItem.create( self.sAffectedFaceItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kTriangles)
            componentItem.setDrawMode(omr.MGeometry.kAll)
            ## Set depth priority to be dormant wire so that edge and vertices
            ## show on top.
            componentItem.setDepthPriority( omr.MRenderItem.sDormantWireDepthPriority )
            list.append(componentItem)

            shader = shaderMgr.getStockShader( omr.MShaderManager.k3dStippleShader )
            if shader:
                ## Assign shader.
                componentItem.setShader(shader, None)

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            componentItem = list[index]

        if componentItem:
            shader = componentItem.getShader()
            if shader:
                ## Set affected color
                theColor = [ 1.0, 1.0, 1.0, 1.0 ]
                self.setSolidColor( shader, theColor )

            enable = ((bool(self.fActiveVerticesSet) or bool(self.fActiveFacesSet)) and self.enableActiveComponentDisplay(path))
            componentItem.enable( enable )

    def updateSelectionComponentItems(self, path, list, shaderMgr):
        ## Example of adding in items for edges and faces selection.

        ## For the vertex selection, we already have a render item that display all the vertices (sVertexItemName)
        ## we could use it for the selection as well.
    
        ## But we have none that display the complete edges or faces,
        ## sAffectedEdgeItemName and sAffectedFaceItemName only display a subset of the edges and faces
        ## that are active or affected (one of their vertices is selected).

        ## In order to be able to perform the selection of this components we'll create new render items
        ## that will only be used for the selection (they will not be visible in the viewport)

        ## Create / update selection edges component render item.
        ##
        selectionItem = None
        index = list.indexOf(self.sEdgeSelectionItemName)
        if index < 0:
            selectionItem = omr.MRenderItem.create( self.sEdgeSelectionItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kLines)

            ## Set draw mode to kSelectionOnly : the item will not be visible in the viewport, but during viewport 2.0 selection
            selectionItem.setDrawMode(omr.MGeometry.kSelectionOnly)

            ## Set the selection mask to kSelectMeshEdges : we want the render item to be used for Edge Components selection
            selectionItem.setSelectionMask( om.MSelectionMask.kSelectMeshEdges )

            ## Set depth priority to be selection so that it is above everything
            selectionItem.setDepthPriority( omr.MRenderItem.sSelectionDepthPriority )
            list.append(selectionItem)

            shader = shaderMgr.getStockShader(omr.MShaderManager.k3dThickLineShader)
            if shader:
                ## Assign shader.
                selectionItem.setShader(shader, None)

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            selectionItem = list[index]

        if selectionItem:
            selectionItem.enable(True)

            mySelectionData = selectionItem.customData()
            if not isinstance(mySelectionData, apiMeshHWSelectionUserData):
                ## create the custom data
                mySelectionData = apiMeshHWSelectionUserData()
                selectionItem.setCustomData(mySelectionData)
            ## update the custom data
            mySelectionData.fMeshGeom = self.fMeshGeom

        ## Create / update selection faces component render item.
        ##
        index = list.indexOf(self.sFaceSelectionItemName)
        if index < 0:
            selectionItem = omr.MRenderItem.create( self.sFaceSelectionItemName, omr.MRenderItem.DecorationItem, omr.MGeometry.kTriangles)

            ## Set draw mode to kSelectionOnly : the item will not be visible in the viewport, but during viewport 2.0 selection
            selectionItem.setDrawMode(omr.MGeometry.kSelectionOnly)

            ## Set the selection mask to kSelectMeshFaces : we want the render item to be used for Face Components selection
            selectionItem.setSelectionMask( om.MSelectionMask.kSelectMeshFaces )

            ## Set depth priority to be selection so that it is above everything
            selectionItem.setDepthPriority( omr.MRenderItem.sSelectionDepthPriority )
            list.append(selectionItem)

            shader = shaderMgr.getStockShader(omr.MShaderManager.k3dSolidShader)
            if shader:
                ## Assign shader.
                selectionItem.setShader(shader, None)

                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            selectionItem = list[index]

        if selectionItem:
            selectionItem.enable(True)

            mySelectionData = selectionItem.customData()
            if not isinstance(mySelectionData, apiMeshHWSelectionUserData):
                ## create the custom data
                mySelectionData = apiMeshHWSelectionUserData()
                selectionItem.setCustomData(mySelectionData)
            ## update the custom data
            mySelectionData.fMeshGeom = self.fMeshGeom

    def updateProxyShadedItem(self, path, list, shaderMgr):
        ## In the event there are no shaded items we create a proxy
        ## render item so we can still see where the object is.

        ## Stock colors
        dormantColor = [ 0.0, 0.0, 1.0, 1.0 ]
        templateColor = [ 0.45, 0.45, 0.45, 1.0 ]
        activeTemplateColor = [ 1.0, 0.5, 0.5, 1.0 ]

        ## Note that we still want to raise it above shaded even though
        ## we don't have a shaded render item for this override.
        ## This will handle in case where there is another shaded object
        ## which overlaps this object in depth
        ##
        raiseAboveShaded = True
        shadedDrawMode = omr.MGeometry.kShaded | omr.MGeometry.kTextured
        ## Mark proxy item as wireframe if not using a material shader
        ##
        useFragmentShader = self.fProxyShader < 0
        if not useFragmentShader:
            shadedDrawMode |= omr.MGeometry.kWireframe

        ## Fragment + stipple shaders required triangles. All others
        ## in the possible list requires lines
        ##
        itemType = omr.MRenderItem.NonMaterialSceneItem
        primitive = omr.MGeometry.kLines
        filledProxy = useFragmentShader or self.fProxyShader == omr.MShaderManager.k3dStippleShader
        if filledProxy:
            itemType = omr.MRenderItem.MaterialSceneItem
            primitive = omr.MGeometry.kTriangles

        depthPriority = omr.MRenderItem.sDormantWireDepthPriority
        if raiseAboveShaded:
            depthPriority = omr.MRenderItem.sActiveWireDepthPriority

        proxyItem = None
        index = list.indexOf(self.sShadedProxyItemName)
        if index < 0:
            proxyItem = omr.MRenderItem.create( self.sShadedProxyItemName, itemType, primitive)
            proxyItem.setDrawMode(shadedDrawMode)
            proxyItem.setDepthPriority( depthPriority )

            proxyItem.setCastsShadows( not self.fExternalItems_NoShadowCast and self.fCastsShadows )
            proxyItem.setReceivesShadows( not self.fExternalItems_NoShadowReceive and self.fReceivesShadows )
            proxyItem.setExcludedFromPostEffects( self.fExternalItems_NoPostEffects )

            list.append(proxyItem)

            ## We'll draw the proxy with a proxy shader as a visual cue
            ##
            shader = None
            if useFragmentShader:
                shader = shaderMgr.getFragmentShader("mayaLambertSurface", "outSurfaceFinal", True)
                sBlue = [ 0.4, 0.4, 1.0 ]
                shader.setParameter("color", sBlue)
                shader.setIsTransparent(False)
            else:
                shader = shaderMgr.getStockShader( self.fProxyShader )

            if shader:
                if not filledProxy:
                    self.setLineWidth(shader, 10.0)

                ## assign shader
                proxyItem.setShader(shader)
                ## once assigned, no need to hold on to shader instance
                shaderMgr.releaseShader(shader)
        else:
            proxyItem = list[index]

        ## As this is a shaded item it is up to the plug-in to determine
        ## on each update how to handle shadowing and effects.
        ## Especially note that shadowing changes on the DAG object will trigger
        ## a call to updateRenderItems()
        ##
        proxyItem.setCastsShadows( not self.fExternalItems_NoShadowCast and self.fCastsShadows )
        proxyItem.setReceivesShadows( not self.fExternalItems_NoShadowReceive and self.fReceivesShadows )
        proxyItem.setExcludedFromPostEffects( self.fExternalItems_NoPostEffects )

        ## Check for any shaded render items. A lack of one indicates
        ## there is no shader assigned to the object.
        ##
        haveShadedItems = False
        for item in list:
            if not item:
                continue
            drawMode = item.drawMode()
            if drawMode == omr.MGeometry.kShaded or drawMode == omr.MGeometry.kTextured:
                if item.name() != self.sShadedTemplateItemName:
                    haveShadedItems = True
                    break

        displayStatus = omr.MGeometryUtilities.displayStatus(path)
        wireColor = omr.MGeometryUtilities.wireframeColor(path)

        ## Note that we do not toggle the item on and off just based on
        ## display state. If this was so then call to MRenderer::setLightsAndShadowsDirty()
        ## would be required as shadow map update does not monitor display state.
        ##
        if proxyItem:
            shader = proxyItem.getShader()

            if displayStatus == omr.MGeometryUtilities.kTemplate:
                self.setSolidColor( shader, wireColor, templateColor )

            elif displayStatus == omr.MGeometryUtilities.kActiveTemplate:
                self.setSolidColor( shader, wireColor, activeTemplateColor )

            elif displayStatus == omr.MGeometryUtilities.kDormant:
                self.setSolidColor( shader, wireColor, dormantColor )

            ## If we are missing shaded render items then enable
            ## the proxy. Otherwise disable it.
            ##
            if filledProxy:
                ## If templated then hide filled proxy
                if path.isTemplated():
                    proxyItem.enable(False)
                else:
                    proxyItem.enable(not haveShadedItems)
            else:
                proxyItem.enable(not haveShadedItems)

    ## Data stream (geometry requirements) handling
    def updateGeometryRequirements(self, requirements, data, activeVertexCount, totalVerts, debugPopulateGeometry):
        ## Examine the geometry requirements and create / update the
        ## appropriate data streams. As render items specify both named and
        ## unnamed data streams, both need to be handled here.

        ## Vertex data
        positionBuffer = None
        positionDataAddress = None
        positionData = None

        vertexNumericIdBuffer = None
        vertexNumericIdDataAddress = None
        vertexNumericIdData = None

        vertexNumericIdPositionBuffer = None
        vertexNumericIdPositionDataAddress = None
        vertexNumericIdPositionData = None

        vertexNumericLocationBuffer = None
        vertexNumericLocationDataAddress = None
        vertexNumericLocationData = None

        vertexNumericLocationPositionBuffer = None
        vertexNumericLocationPositionDataAddress = None
        vertexNumericLocationPositionData = None

        activeVertexPositionBuffer = None
        activeVertexPositionDataAddress = None
        activeVertexPositionData = None

        activeVertexUVBuffer = None
        activeVertexUVDataAddress = None
        activeVertexUVData = None

        faceCenterPositionBuffer = None
        faceCenterPositionDataAddress = None
        faceCenterPositionData = None

        normalBuffer = None
        normalDataAddress = None
        normalData = None

        cpvBuffer = None
        cpvDataAddress = None
        cpvData = None

        uvBuffer = None
        uvDataAddress = None
        uvData = None

        numUVs = self.fMeshGeom.uvcoords.uvcount()

        descList = requirements.vertexRequirements()
        satisfiedRequirements = [False,] * len(descList)
        for i in xrange(len(descList)):
            desc = descList[i]
            ## Fill in vertex data for drawing active vertex components (if drawSharedActiveVertices=True)
            ##
            if self.fDrawSharedActiveVertices and (desc.name == self.sActiveVertexStreamName):
                if desc.semantic == omr.MGeometry.kPosition:
                    if not activeVertexPositionBuffer:
                        activeVertexPositionBuffer = data.createVertexBuffer(desc)
                        if activeVertexPositionBuffer:
                            satisfiedRequirements[i] = True
                            if debugPopulateGeometry:
                                print ">>> Fill in data for active vertex requirement '" + desc.name + "'. Semantic = kPosition"
                            activeVertexPositionDataAddress = activeVertexPositionBuffer.acquire(activeVertexCount, True) ## writeOnly - we don't need the current buffer values
                            if activeVertexPositionDataAddress:
                                activeVertexPositionData = ((ctypes.c_float * 3)*activeVertexCount).from_address(activeVertexPositionDataAddress)

                elif desc.semantic == omr.MGeometry.kTexture:
                    if not activeVertexUVBuffer:
                        activeVertexUVBuffer = data.createVertexBuffer(desc)
                        if activeVertexUVBuffer:
                            satisfiedRequirements[i] = True
                            if debugPopulateGeometry:
                                print ">>> Fill in data for active vertex requirement '" + desc.name + "'. Semantic = kTexture"
                            activeVertexUVDataAddress = activeVertexUVBuffer.acquire(activeVertexCount, True) ## writeOnly - we don't need the current buffer values
                            if activeVertexUVDataAddress:
                                activeVertexUVData = ((ctypes.c_float * 3)*activeVertexCount).from_address(activeVertexUVDataAddress)
                else:
                    ## do nothing for stuff we don't understand
                    pass

            ## Fill in vertex data for drawing face center components (if fDrawFaceCenters=True)
            ##
            elif self.fDrawFaceCenters and desc.name == self.sFaceCenterStreamName:
                if desc.semantic == omr.MGeometry.kPosition:
                    if not faceCenterPositionBuffer:
                        faceCenterPositionBuffer = data.createVertexBuffer(desc)
                        if faceCenterPositionBuffer:
                            satisfiedRequirements[i] = True
                            if debugPopulateGeometry:
                                print ">>> Fill in data for face center vertex requirement '" + desc.name + "'. Semantic = kPosition"
                            faceCenterPositionDataAddress = faceCenterPositionBuffer.acquire(self.fMeshGeom.faceCount, True) ## writeOnly - we don't need the current buffer values
                            if faceCenterPositionDataAddress:
                                faceCenterPositionData = ((ctypes.c_float * 3)*self.fMeshGeom.faceCount).from_address(faceCenterPositionDataAddress)

                else:
                    ## do nothing for stuff we don't understand
                    pass

            ## Fill vertex stream data used for dormant vertex, wireframe and shaded drawing.
            ## Fill also for active vertices if (fDrawSharedActiveVertices=False)
            else:
                if desc.semantic == omr.MGeometry.kPosition:
                    if desc.name == self.sVertexIdItemName:
                        if not vertexNumericIdPositionBuffer:
                            vertexNumericIdPositionBuffer = data.createVertexBuffer(desc)
                            if vertexNumericIdPositionBuffer:
                                satisfiedRequirements[i] = True
                                if debugPopulateGeometry:
                                    print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kPosition"
                                    print "Acquire 3loat-numeric position buffer"
                                vertexNumericIdPositionDataAddress = vertexNumericIdPositionBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                                if vertexNumericIdPositionDataAddress:
                                    vertexNumericIdPositionData = ((ctypes.c_float * 3)*totalVerts).from_address(vertexNumericIdPositionDataAddress)

                    elif desc.name == self.sVertexPositionItemName:
                        if not vertexNumericLocationPositionBuffer:
                            vertexNumericLocationPositionBuffer = data.createVertexBuffer(desc)
                            if vertexNumericLocationPositionBuffer:
                                satisfiedRequirements[i] = True
                                if debugPopulateGeometry:
                                    print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kPosition"
                                    print "Acquire 3loat-numeric position buffer"
                                vertexNumericLocationPositionDataAddress = vertexNumericLocationPositionBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                                if vertexNumericLocationPositionDataAddress:
                                    vertexNumericLocationPositionData = ((ctypes.c_float * 3)*totalVerts).from_address(vertexNumericLocationPositionDataAddress)

                    else:
                        if not positionBuffer:
                            positionBuffer = data.createVertexBuffer(desc)
                            if positionBuffer:
                                satisfiedRequirements[i] = True
                                if debugPopulateGeometry:
                                    print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kPosition"
                                    print "Acquire unnamed position buffer"
                                positionDataAddress = positionBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                                if positionDataAddress:
                                    positionData = ((ctypes.c_float * 3)*totalVerts).from_address(positionDataAddress)

                elif desc.semantic == omr.MGeometry.kNormal:
                    if not normalBuffer:
                        normalBuffer = data.createVertexBuffer(desc)
                        if normalBuffer:
                            satisfiedRequirements[i] = True
                            if debugPopulateGeometry:
                                print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kNormal"
                            normalDataAddress = normalBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                            if normalDataAddress:
                                normalData = ((ctypes.c_float * 3)*totalVerts).from_address(normalDataAddress)

                elif desc.semantic == omr.MGeometry.kTexture:
                    numericValue = "numericvalue"
                    numeric3Value ="numeric3value"

                    ## Fill in single numeric field
                    if desc.semanticName.lower() == numericValue and desc.name == self.sVertexIdItemName:
                        if not vertexNumericIdBuffer:
                            vertexNumericIdBuffer = data.createVertexBuffer(desc)
                            if vertexNumericIdBuffer:
                                satisfiedRequirements[i] = True
                                if debugPopulateGeometry:
                                    print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kTexture"
                                    print "Acquire 1loat numeric buffer"
                                vertexNumericIdDataAddress = vertexNumericIdBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                                if vertexNumericIdDataAddress:
                                    vertexNumericIdData = ((ctypes.c_float * 1)*totalVerts).from_address(vertexNumericIdDataAddress)

                    ## Fill in triple numeric field
                    elif desc.semanticName.lower() == numeric3Value and desc.name == self.sVertexPositionItemName:
                        if not vertexNumericLocationBuffer:
                            vertexNumericLocationBuffer = data.createVertexBuffer(desc)
                            if vertexNumericLocationBuffer:
                                satisfiedRequirements[i] = True
                                if debugPopulateGeometry:
                                    print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kTexture"
                                    print "Acquire 3loat numeric location buffer"
                                vertexNumericLocationDataAddress = vertexNumericLocationBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                                if vertexNumericLocationDataAddress:
                                    vertexNumericLocationData = ((ctypes.c_float * 3)*totalVerts).from_address(vertexNumericLocationDataAddress)

                    ## Fill in uv values
                    elif desc.name != self.sVertexIdItemName and desc.name != self.sVertexPositionItemName:
                        if not uvBuffer:
                            uvBuffer = data.createVertexBuffer(desc)
                            if uvBuffer:
                                satisfiedRequirements[i] = True
                                if debugPopulateGeometry:
                                    print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kTexture"
                                    print "Acquire a uv buffer"
                                uvDataAddress = uvBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                                if uvDataAddress:
                                    uvData = ((ctypes.c_float * 2)*totalVerts).from_address(uvDataAddress)

                elif desc.semantic == omr.MGeometry.kColor:
                    if not cpvBuffer:
                        cpvBuffer = data.createVertexBuffer(desc)
                        if cpvBuffer:
                            satisfiedRequirements[i] = True
                            if debugPopulateGeometry:
                                print ">>> Fill in data for requirement '" + desc.name + "'. Semantic = kColor"
                            cpvDataAddress = cpvBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                            if cpvDataAddress:
                                cpvData = ((ctypes.c_float * 4)*totalVerts).from_address(cpvDataAddress)

                else:
                    ## do nothing for stuff we don't understand
                    pass

        vid = 0
        pid = 0
        nid = 0
        uvid = 0
        cid = 0
        for i in xrange(self.fMeshGeom.faceCount):
            ## ignore degenerate faces
            numVerts = self.fMeshGeom.face_counts[i]
            if numVerts > 2:
                for v in xrange(numVerts):
                    if any((positionData, vertexNumericIdPositionData, vertexNumericLocationPositionData, vertexNumericLocationData)):
                        position = self.fMeshGeom.vertices[self.fMeshGeom.face_connects[vid]]
                        ## Position used as position
                        if positionData:
                            positionData[pid][0] = position[0]
                            positionData[pid][1] = position[1]
                            positionData[pid][2] = position[2]

                        ## Move the id's a bit to avoid overlap. Position used as position.
                        if vertexNumericIdPositionData:
                            vertexNumericIdPositionData[pid][0] = position[0]+1.0
                            vertexNumericIdPositionData[pid][1] = position[1]+1.0
                            vertexNumericIdPositionData[pid][2] = position[2]+1.0

                        ## Move the locations a bit to avoid overlap. Position used as position.
                        if vertexNumericLocationPositionData:
                            vertexNumericLocationPositionData[pid][0] = position[0]+3.0
                            vertexNumericLocationPositionData[pid][1] = position[1]+3.0
                            vertexNumericLocationPositionData[pid][2] = position[2]+3.0

                        ## Position used as numeric display.
                        if vertexNumericLocationData:
                            vertexNumericLocationData[pid][0] = position[0]
                            vertexNumericLocationData[pid][1] = position[1]
                            vertexNumericLocationData[pid][2] = position[2]

                        pid += 1

                    if normalData:
                        normal = self.fMeshGeom.normals[self.fMeshGeom.face_connects[vid]]
                        normalData[nid][0] = normal[0]
                        normalData[nid][1] = normal[1]
                        normalData[nid][2] = normal[2]

                        nid += 1

                    if uvData:
                        uv = [0, 0]
                        if numUVs > 0:
                            uvNum = self.fMeshGeom.uvcoords.uvId(vid)
                            uv = self.fMeshGeom.uvcoords.getUV(uvNum)
                        uvData[uvid][0] = uv[0]
                        uvData[uvid][1] = uv[0]

                        uvid += 1

                    ## Just same fake colors to show filling in requirements for
                    ## color-per-vertex (CPV)
                    if cpvData:
                        position = self.fMeshGeom.vertices[self.fMeshGeom.face_connects[vid]]
                        cpvData[cid][0] = position[0]
                        cpvData[cid][1] = position[1]
                        cpvData[cid][2] = position[2]
                        cpvData[cid][3] = 1.0

                        cid += 1

                    ## Vertex id's used for numeric display
                    if vertexNumericIdData:
                        vertexNumericIdData[vid] = fMeshGeom.face_connects[vid]
                        pass

                    vid += 1

            elif numVerts > 0:
                vid += numVerts

        if positionDataAddress:
            positionBuffer.commit(positionDataAddress)

        if normalDataAddress:
            normalBuffer.commit(normalDataAddress)

        if uvDataAddress:
            uvBuffer.commit(uvDataAddress)

        if cpvDataAddress:
            cpvBuffer.commit(cpvDataAddress)
        
        if vertexNumericIdDataAddress:
            vertexNumericIdBuffer.commit(vertexNumericIdDataAddress)

        if vertexNumericIdPositionDataAddress:
            vertexNumericIdPositionBuffer.commit(vertexNumericIdPositionDataAddress)

        if vertexNumericLocationDataAddress:
            vertexNumericLocationBuffer.commit(vertexNumericLocationDataAddress)

        if vertexNumericLocationPositionDataAddress:
            vertexNumericLocationPositionBuffer.commit(vertexNumericLocationPositionDataAddress)

        ## Fill in active vertex data buffer (only when fDrawSharedActiveVertices=True
        ## which results in activeVertexPositionDataAddress and activeVertexPositionBuffer being non-NULL)
        ##
        if activeVertexPositionData:
            if debugPopulateGeometry:
                print ">>> Fill in the data for active vertex position buffer base on component list"

            ## Fill in position buffer with positions based on active vertex indexing list
            ##
            if activeVertexCount > len(self.fMeshGeom.vertices):
                activeVertexCount = len(self.fMeshGeom.vertices)

            for i in xrange(activeVertexCount):
                position = self.fMeshGeom.vertices[ self.fActiveVertices[i] ]
                activeVertexPositionData[i][0] = position[0]
                activeVertexPositionData[i][1] = position[1]
                activeVertexPositionData[i][2] = position[2]

            activeVertexPositionBuffer.commit(activeVertexPositionDataAddress)

        if activeVertexUVData:
            if debugPopulateGeometry:
                print ">>> Fill in the data for active vertex uv buffer base on component list"

            ## Fill in position buffer with positions based on active vertex indexing list
            ##
            if activeVertexCount > len(self.fMeshGeom.vertices):
                activeVertexCount = len(self.fMeshGeom.vertices)

            for i in xrange(activeVertexCount):
                activeVertexUVData[i] = i / activeVertexCount

            activeVertexUVBuffer.commit(activeVertexUVDataAddress)

        ## Fill in face center data buffer (only when fDrawFaceCenter=True
        ## which results in faceCenterPositionDataAddress and faceCenterPositionBuffer being non-NULL)
        ##
        if faceCenterPositionData:
            if debugPopulateGeometry:
                print ">>> Fill in the data for face center position buffer"

            ## Fill in face center buffer with positions based on realtime calculations.
            ##
            pid = 0
            vid = 0
            for faceId in xrange(self.fMeshGeom.faceCount):
                ##tmp variables for calculating the face center position.
                x = 0.0
                y = 0.0
                z = 0.0

                faceCenterPosition = om.MPoint()

                ## ignore degenerate faces
                numVerts = self.fMeshGeom.face_counts[faceId]
                if numVerts > 2:
                    for v in xrange(numVerts):
                        face_vertex_position = self.fMeshGeom.vertices[self.fMeshGeom.face_connects[vid]]
                        x += face_vertex_position[0]
                        y += face_vertex_position[1]
                        z += face_vertex_position[2]

                        vid += 1

                    faceCenterPosition = om.MPoint(x, y, z) / numVerts

                elif numVerts > 0:
                    vid += numVerts

                faceCenterPositionData[faceId][0] = faceCenterPosition[0]
                faceCenterPositionData[faceId][1] = faceCenterPosition[1]
                faceCenterPositionData[faceId][2] = faceCenterPosition[2]

            faceCenterPositionBuffer.commit(faceCenterPositionDataAddress)

        ## Run around a second time and handle duplicate buffers and unknown buffers
        ##
        for i in xrange(len(descList)):
            if satisfiedRequirements[i]:
                continue
            desc = descList[i]
            if self.fDrawSharedActiveVertices and (desc.name == self.sActiveVertexStreamName):
                if desc.semantic == omr.MGeometry.kPosition:
                    satisfiedRequirements[i] = True
                    self.cloneVertexBuffer(activeVertexPositionBuffer, data, desc, activeVertexCount, debugPopulateGeometry)
                elif desc.semantic == omr.MGeometry.kTexture:
                    satisfiedRequirements[i] = True
                    self.cloneVertexBuffer(activeVertexUVBuffer, data, desc, activeVertexCount, debugPopulateGeometry)
            elif self.fDrawFaceCenters and desc.name == self.sFaceCenterStreamName:
                if desc.semantic == omr.MGeometry.kPosition:
                    satisfiedRequirements[i] = True
                    self.cloneVertexBuffer(faceCenterPositionBuffer, data, desc, self.fMeshGeom.faceCount, debugPopulateGeometry)
            else:
                if desc.semantic == omr.MGeometry.kPosition:
                    if desc.name == self.sVertexIdItemName:
                        satisfiedRequirements[i] = True
                        self.cloneVertexBuffer(vertexNumericIdPositionBuffer, data, desc, totalVerts, debugPopulateGeometry)
                    elif desc.name == self.sVertexPositionItemName:
                        satisfiedRequirements[i] = True
                        self.cloneVertexBuffer(vertexNumericLocationPositionBuffer, data, desc, totalVerts, debugPopulateGeometry)
                    else:
                        satisfiedRequirements[i] = True
                        self.cloneVertexBuffer(positionBuffer, data, desc, totalVerts, debugPopulateGeometry)
                elif desc.semantic == omr.MGeometry.kNormal:
                    satisfiedRequirements[i] = True
                    self.cloneVertexBuffer(normalBuffer, data, desc, totalVerts, debugPopulateGeometry)
                elif desc.semantic == omr.MGeometry.kTexture:
                    numericValue = "numericvalue"
                    numeric3Value ="numeric3value"
                    if desc.semanticName.lower() == numericValue and desc.name == self.sVertexIdItemName:
                        satisfiedRequirements[i] = True
                        self.cloneVertexBuffer(vertexNumericIdBuffer, data, desc, totalVerts, debugPopulateGeometry)
                    elif desc.semanticName.lower() == numeric3Value and desc.name == self.sVertexPositionItemName:
                        satisfiedRequirements[i] = True
                        self.cloneVertexBuffer(vertexNumericLocationBuffer, data, desc, totalVerts, debugPopulateGeometry)
                    elif desc.name != self.sVertexIdItemName and desc.name != self.sVertexPositionItemName:
                        satisfiedRequirements[i] = True
                        self.cloneVertexBuffer(uvBuffer, data, desc, totalVerts, debugPopulateGeometry)
                elif desc.semantic == omr.MGeometry.kColor:
                    satisfiedRequirements[i] = True
                    self.cloneVertexBuffer(cpvBuffer, data, desc, totalVerts, debugPopulateGeometry)
            
            if not satisfiedRequirements[i]:
                ## We have a strange buffer request we do not understand. Provide a set of Zeros sufficient to cover
                ## totalVerts:
                destBuffer = data.createVertexBuffer(desc)
                if destBuffer:
                    satisfiedRequirements[i] = True
                    if debugPopulateGeometry:
                        print ">>> Fill in dummy requirement '%s'" % (desc.name, )
                    destBufferDataAddress = destBuffer.acquire(totalVerts, True) ## writeOnly - we don't need the current buffer values
                    if destBufferDataAddress:
                        destBufferData = ((ctypes.c_float * desc.dimension)*totalVerts).from_address(destBufferDataAddress)
                        if destBufferData:
                            for j in xrange(totalVerts):
                                if desc.dimension == 4:
                                    destBufferData[j] = (1.0, 0.0, 0.0, 1.0)
                                elif desc.dimension == 3:
                                    destBufferData[j] = (1.0, 0.0, 0.0)
                                else:
                                    for k in xrange(desc.dimension):
                                        destBufferData[j][k] = 0.0
                        destBuffer.commit(destBufferDataAddress)

    ##  Clone a vertex buffer to fulfill a duplicate requirement.
    ##   Can happen for effects asking for multiple UV streams by
    ##   name.
    def cloneVertexBuffer(self, srcBuffer, data, desc, dataSize, debugPopulateGeometry):
        if srcBuffer:
            destBuffer = data.createVertexBuffer(desc)
            if destBuffer:
                if debugPopulateGeometry:
                    print ">>> Cloning requirement '%s'" % (desc.name, )
                destBufferDataAddress = destBuffer.acquire(dataSize, True) ## writeOnly - we don't need the current buffer values
                srcBufferDataAddress = srcBuffer.map()
                if destBufferDataAddress and srcBufferDataAddress:
                    destBufferData = ((ctypes.c_float * desc.dimension)*dataSize).from_address(destBufferDataAddress)
                    srcBufferData = ((ctypes.c_float * desc.dimension)*dataSize).from_address(srcBufferDataAddress)
                    if destBufferData and srcBufferData:
                        for j in xrange(dataSize):
                            for k in xrange(desc.dimension):
                                destBufferData[j][k] = srcBufferData[j][k]
                    destBuffer.commit(destBufferDataAddress)
                srcBuffer.unmap()

    ## Indexing for render item handling methods
    def updateIndexingForWireframeItems(self, wireIndexBuffer, item, data, totalVerts):
        ## Create / update indexing required to draw wireframe render items.
        ## There can be more than one render item using the same wireframe indexing
        ## so it is passed in as an argument. If it is not null then we can
        ## reuse it instead of creating new indexing.
    
        ## Wireframe index buffer is same for both wireframe and selected render item
        ## so we only compute and allocate it once, but reuse it for both render items
        if not wireIndexBuffer:
            wireIndexBuffer = data.createIndexBuffer(omr.MGeometry.kUnsignedInt32)
            if wireIndexBuffer:
                dataAddress = wireIndexBuffer.acquire(2*totalVerts, True) ## writeOnly - we don't need the current buffer values
                if dataAddress:
                    data = (ctypes.c_uint * (2*totalVerts)).from_address(dataAddress)
                    vid = 0
                    first = 0
                    idx = 0
                    for faceIdx in xrange(self.fMeshGeom.faceCount):
                        ## ignore degenerate faces
                        numVerts = self.fMeshGeom.face_counts[faceIdx]
                        if numVerts > 2:
                            first = vid
                            for v in xrange(numVerts-1):
                                data[idx] = vid
                                vid += 1
                                idx += 1
                                data[idx] = vid
                                idx += 1

                            data[idx] = vid
                            vid += 1
                            idx += 1
                            data[idx] = first
                            idx += 1

                        else:
                            vid += numVerts

                    wireIndexBuffer.commit(dataAddress)

        ## Associate same index buffer with either render item
        if wireIndexBuffer:
            item.associateWithIndexBuffer(wireIndexBuffer)

    def updateIndexingForDormantVertices(self, item, data, numTriangles):
        ## Create / update indexing for render items which draw dormant vertices

        indexBuffer = data.createIndexBuffer(omr.MGeometry.kUnsignedInt32)
        if indexBuffer:
            dataAddress = indexBuffer.acquire(3*numTriangles, True) ## writeOnly - we don't need the current buffer values
            if dataAddress:
                data = (ctypes.c_uint*(3*numTriangles)).from_address(dataAddress)
                ## compute index data for triangulated convex polygons sharing
                ## poly vertex data among triangles
                base = 0
                idx = 0
                for faceIdx in xrange(self.fMeshGeom.faceCount):
                    ## ignore degenerate faces
                    numVerts = self.fMeshGeom.face_counts[faceIdx]
                    if numVerts > 2:
                        for v in xrange(1, numVerts-1):
                            data[idx] = base
                            data[idx+1] = base+v
                            data[idx+2] = base+v+1
                            idx += 3

                        base += numVerts

                indexBuffer.commit(dataAddress)

            item.associateWithIndexBuffer(indexBuffer)

    def updateIndexingForFaceCenters(self, item, data, debugPopulateGeometry):
        ## Create / update indexing for render items which draw face centers

        indexBuffer = data.createIndexBuffer(omr.MGeometry.kUnsignedInt32)
        if indexBuffer:
            dataAddress = indexBuffer.acquire(self.fMeshGeom.faceCount, True) ## writeOnly - we don't need the current buffer values
            if dataAddress:
                data = (ctypes.c_uint * self.fMeshGeom.faceCount).from_address(dataAddress)
                if debugPopulateGeometry:
                    print ">>> Set up indexing for face centers"

                for i in xrange(self.fMeshGeom.faceCount):
                    data[i] = 0
                    pass

                idx = 0
                for i in xrange(self.fMeshGeom.faceCount):
                    ## ignore degenerate faces
                    numVerts = self.fMeshGeom.face_counts[i]
                    if numVerts > 2:
                        data[idx] = idx
                        idx += 1

                indexBuffer.commit(dataAddress)

            item.associateWithIndexBuffer(indexBuffer)

    def updateIndexingForVertices(self, item, data, numTriangles, activeVertexCount, debugPopulateGeometry):
        ## Create / update indexing for render items which draw active vertices

        indexBuffer = data.createIndexBuffer(omr.MGeometry.kUnsignedInt32)
        if indexBuffer:
            dataAddress = None

            ## If drawing shared active vertices then the indexing degenerates into
            ## a numerically increasing index value. Otherwise a remapping from
            ## the active vertex list indexing to the unshared position stream is required.
            ##
            ## 1. Create indexing for shared positions. In this case it
            ## is a degenerate list since the position buffer was created
            ## in linear ascending order.
            ##
            if self.fDrawSharedActiveVertices:
                dataAddress = indexBuffer.acquire(activeVertexCount, True) ## writeOnly - we don't need the current buffer values
                if dataAddress:
                    data = (ctypes.c_uint*activeVertexCount).from_address(dataAddress)
                    if debugPopulateGeometry:
                        print ">>> Set up indexing for shared vertices"
 
                    for i in xrange(activeVertexCount):
                        data[i] = i

            ## 2. Create indexing to remap to unshared positions
            ##
            else:
                if debugPopulateGeometry:
                    print ">>> Set up indexing for unshared vertices"

                vertexCount = 3*numTriangles
                dataAddress = indexBuffer.acquire(vertexCount, True) ## writeOnly - we don't need the current buffer values
                if dataAddress:
                    data = (ctypes.c_uint*vertexCount).from_address(dataAddress)
                    for i in xrange(vertexCount):
                        data[i] = vertexCount+1

                    selectionIdSet = self.fActiveVerticesSet

                    ## compute index data for triangulated convex polygons sharing
                    ## poly vertex data among triangles
                    base = 0
                    lastFound = 0
                    idx = 0
                    for faceIdx in xrange(self.fMeshGeom.faceCount):
                        ## ignore degenerate faces
                        numVerts = self.fMeshGeom.face_counts[faceIdx]
                        if numVerts > 2:
                            for v in xrange(1, numVerts-1):
                                vertexId = self.fMeshGeom.face_connects[base]
                                if vertexId in selectionIdSet:
                                    lastFound = base
                                    data[idx] = lastFound
                                    idx += 1

                                vertexId = self.fMeshGeom.face_connects[base+v]
                                if vertexId in selectionIdSet:
                                    lastFound = base+v
                                    data[idx] = lastFound
                                    idx += 1

                                vertexId = self.fMeshGeom.face_connects[base+v+1]
                                if vertexId in selectionIdSet:
                                    lastFound = base+v+1
                                    data[idx] = lastFound
                                    idx +1

                            base += numVerts

                    for i in xrange(vertexCount):
                        if data[i] == vertexCount+1:
                             data[i] = lastFound

            if dataAddress:
                indexBuffer.commit(dataAddress)

            item.associateWithIndexBuffer(indexBuffer)

    def updateIndexingForEdges(self, item, data, totalVerts, fromSelection):
        ## Create / update indexing for render items which draw affected edges

        indexBuffer = data.createIndexBuffer(omr.MGeometry.kUnsignedInt32)
        if indexBuffer:
            totalEdges = 2*totalVerts
            totalEdgesP1 = 2*totalVerts+1
            dataAddress = indexBuffer.acquire(totalEdges, True) ## writeOnly - we don't need the current buffer values
            if dataAddress:
                data = (ctypes.c_uint*totalEdges).from_address(dataAddress)
                for i in xrange(totalEdges):
                    data[i] = totalEdgesP1
                    pass

                displayAll = not fromSelection
                displayActives = (not displayAll and bool(self.fActiveEdgesSet))
                displayAffected = (not displayAll and not displayActives)

                selectionIdSet = None
                if displayActives:
                    selectionIdSet = self.fActiveEdgesSet
                elif displayAffected:
                    selectionIdSet = self.fActiveVerticesSet

                base = 0
                lastFound = 0
                idx = 0
                edgeId = 0
                for faceIdx in xrange(self.fMeshGeom.faceCount):
                    ## ignore degenerate faces
                    numVerts = self.fMeshGeom.face_counts[faceIdx]
                    if numVerts > 2:
                        for v in xrange(numVerts):
                            enableEdge = displayAll
                            vindex1 = base + (v % numVerts)
                            vindex2 = base + ((v+1) % numVerts)

                            if displayAffected:
                                ## Check either ends of an "edge" to see if the
                                ## vertex is in the active vertex list
                                ##
                                vertexId = self.fMeshGeom.face_connects[vindex1]
                                if vertexId in selectionIdSet:
                                    enableEdge = True
                                    lastFound = vindex1

                                if not enableEdge:
                                    vertexId2 = self.fMeshGeom.face_connects[vindex2]
                                    if vertexId2 in selectionIdSet:
                                        enableEdge = True
                                        lastFound = vindex2

                            elif displayActives:
                                ## Check if the edge is active
                                ##
                                if edgeId in selectionIdSet:
                                    enableEdge = True
                                    lastFound = vindex1

                            ## Add indices for "edge"
                            if enableEdge:
                                data[idx] = vindex1
                                idx += 1
                                data[idx] = vindex2
                                idx += 1
                            edgeId += 1

                        base += numVerts

                if not displayAll:
                    for i in xrange(totalEdges):
                        if data[i] == totalEdgesP1:
                            data[i] = lastFound

                indexBuffer.commit(dataAddress)

            item.associateWithIndexBuffer(indexBuffer)

    def updateIndexingForFaces(self, item, data, numTriangles, fromSelection):
        ## Create / update indexing for render items which draw affected/active faces

        indexBuffer = data.createIndexBuffer(omr.MGeometry.kUnsignedInt32)
        if indexBuffer:
            numTriangleVertices = 3*numTriangles
            dataAddress = indexBuffer.acquire(numTriangleVertices, True) ## writeOnly - we don't need the current buffer values
            if dataAddress:
                data = (ctypes.c_uint*numTriangleVertices).from_address(dataAddress)
                for i in xrange(numTriangleVertices):
                    data[i] = numTriangleVertices+1
                    pass

                displayAll = not fromSelection
                displayActives = (not displayAll and bool(self.fActiveFacesSet))
                displayAffected = (not displayAll and not displayActives)

                selectionIdSet = None
                if displayActives:
                    selectionIdSet = self.fActiveFacesSet
                elif displayAffected:
                    selectionIdSet = self.fActiveVerticesSet

                base = 0
                lastFound = 0
                idx = 0
                for faceIdx in xrange(self.fMeshGeom.faceCount):
                    ## ignore degenerate faces
                    numVerts = self.fMeshGeom.face_counts[faceIdx]
                    if numVerts > 2:
                        enableFace = displayAll

                        if displayAffected:
                            ## Scan for any vertex in the active list
                            ##
                            for v in xrange(1, numVerts-1):
                                vertexId = self.fMeshGeom.face_connects[base]
                                if vertexId in selectionIdSet:
                                    enableFace = True
                                    lastFound = base

                                if not enableFace:
                                    vertexId2 = self.fMeshGeom.face_connects[base+v]
                                    if vertexId2 in selectionIdSet:
                                        enableFace = True
                                        lastFound = base+v

                                if not enableFace:
                                    vertexId3 = self.fMeshGeom.face_connects[base+v+1]
                                    if vertexId3 in selectionIdSet:
                                        enableFace = True
                                        lastFound = base+v+1

                        elif displayActives:
                            ## Check if the face is active
                            ##
                            if faceIdx in selectionIdSet:
                                enableFace = True
                                lastFound = base

                        ## Found an active face
                        ## or one active vertex on the triangle so add indexing for the entire triangle.
                        ##
                        if enableFace:
                            for v in xrange(1, numVerts-1):
                                data[idx] = base
                                data[idx+1] = base+v
                                data[idx+2] = base+v+1
                                idx += 3

                        base += numVerts

                if not displayAll:
                    for i in xrange(numTriangleVertices):
                        if data[i] == numTriangleVertices+1:
                            data[i] = lastFound

                indexBuffer.commit(dataAddress)

            item.associateWithIndexBuffer(indexBuffer)

    def updateIndexingForShadedTriangles(self, item, data, numTriangles):
        ## Create / update indexing for render items which draw filled / shaded
        ## triangles.

        indexBuffer = data.createIndexBuffer(omr.MGeometry.kUnsignedInt32)
        if indexBuffer:
            dataAddress = indexBuffer.acquire(3*numTriangles, True) ## writeOnly - we don't need the current buffer values
            if dataAddress:
                data = (ctypes.c_uint * (3*numTriangles)).from_address(dataAddress)
                ## compute index data for triangulated convex polygons sharing
                ## poly vertex data among triangles
                base = 0
                idx = 0
                for faceIdx in xrange(self.fMeshGeom.faceCount):
                    ## ignore degenerate faces
                    numVerts = self.fMeshGeom.face_counts[faceIdx]
                    if numVerts > 2:
                        for v in xrange(1, numVerts-1):
                            data[idx] = base
                            data[idx+1] = base+v
                            data[idx+2] = base+v+1
                            idx += 3

                        base += numVerts

                indexBuffer.commit(dataAddress)

            item.associateWithIndexBuffer(indexBuffer)

################################################################################
##
## Node registry
##
## Registers/Deregisters apiMeshData geometry data,
## apiMeshCreator DG node, and apiMeshShape user defined shape.
##
################################################################################
##
## Strings for registering vp2 draw overrides. Plugin includes implementations
## of MPxSubSceneOverride and MPxGeometryOverride, set the boolean flag below
## to choose which is used.
sUseSubSceneOverride = False
sDrawDbClassification = "drawdb/geometry/apiMesh"
if sUseSubSceneOverride:
    sDrawDbClassification = "drawdb/subscene/apiMesh"
sDrawRegistrantId = "apiMeshPlugin"


def initializePlugin(obj):
    plugin = om.MFnPlugin(obj, "Autodesk", "3.0", "Any")

    global sUseSubSceneOverride, sDrawDbClassification, sDrawRegistrantId

    try:
        plugin.registerData("apiMeshData", apiMeshData.id, apiMeshData.creator, om.MPxData.kGeometryData)
    except:
        sys.stderr.write("Failed to register data\n")
        raise

    try:
        plugin.registerShape("apiMesh", apiMesh.id, apiMesh.creator, apiMesh.initialize, apiMeshUI.creator, sDrawDbClassification)
    except:
        sys.stderr.write("Failed to register node\n")
        raise

    try:
        plugin.registerNode("apiMeshCreator", apiMeshCreator.id, apiMeshCreator.creator, apiMeshCreator.initialize)
    except:
        sys.stderr.write("Failed to register node\n")
        raise

    try:
        if sUseSubSceneOverride:
            omr.MDrawRegistry.registerSubSceneOverrideCreator(sDrawDbClassification, sDrawRegistrantId, apiMeshSubSceneOverride.creator)
        else:
            omr.MDrawRegistry.registerGeometryOverrideCreator(sDrawDbClassification, sDrawRegistrantId, apiMeshGeometryOverride.creator)
    except:
        sys.stderr.write("Failed to register override\n")
        raise

    try:
        if sUseSubSceneOverride:
            omr.MDrawRegistry.registerComponentConverter(apiMeshSubSceneOverride.sVertexSelectionName, simpleComponentConverter_subsceneOverride.creatorVertexSelection)
            omr.MDrawRegistry.registerComponentConverter(apiMeshSubSceneOverride.sEdgeSelectionName, simpleComponentConverter_subsceneOverride.creatorEdgeSelection)
            omr.MDrawRegistry.registerComponentConverter(apiMeshSubSceneOverride.sFaceSelectionName, simpleComponentConverter_subsceneOverride.creatorFaceSelection)
        else:
            omr.MDrawRegistry.registerComponentConverter(apiMeshGeometryOverride.sVertexItemName, meshVertComponentConverter_geometryOverride.creator)
            omr.MDrawRegistry.registerComponentConverter(apiMeshGeometryOverride.sEdgeSelectionItemName, meshEdgeComponentConverter_geometryOverride.creator)
            omr.MDrawRegistry.registerComponentConverter(apiMeshGeometryOverride.sFaceSelectionItemName, meshFaceComponentConverter_geometryOverride.creator)
    except:
        sys.stderr.write("Failed to register component converters\n")
        raise

def uninitializePlugin(obj):
    plugin = om.MFnPlugin(obj)

    global sUseSubSceneOverride, sDrawDbClassification, sDrawRegistrantId

    try:
        if sUseSubSceneOverride:
            omr.MDrawRegistry.deregisterComponentConverter(apiMeshSubSceneOverride.sVertexSelectionName)
            omr.MDrawRegistry.deregisterComponentConverter(apiMeshSubSceneOverride.sEdgeSelectionName)
            omr.MDrawRegistry.deregisterComponentConverter(apiMeshSubSceneOverride.sFaceSelectionName)
        else:
            omr.MDrawRegistry.deregisterComponentConverter(apiMeshGeometryOverride.sVertexItemName)
            omr.MDrawRegistry.deregisterComponentConverter(apiMeshGeometryOverride.sEdgeSelectionItemName)
            omr.MDrawRegistry.deregisterComponentConverter(apiMeshGeometryOverride.sFaceSelectionItemName)
    except:
        sys.stderr.write("Failed to deregister component converters\n")
        pass

    try:
        if sUseSubSceneOverride:
            omr.MDrawRegistry.deregisterSubSceneOverrideCreator(sDrawDbClassification, sDrawRegistrantId)
        else:
            omr.MDrawRegistry.deregisterGeometryOverrideCreator(sDrawDbClassification, sDrawRegistrantId)
    except:
        sys.stderr.write("Failed to deregister override\n")
        pass

    try:
        plugin.deregisterNode(apiMeshCreator.id)
    except:
        sys.stderr.write("Failed to deregister node\n")
        pass

    try:
        plugin.deregisterNode(apiMesh.id)
    except:
        sys.stderr.write("Failed to deregister node\n")
        pass

    try:
        plugin.deregisterData(apiMeshData.id)
    except:
        sys.stderr.write("Failed to deregister data\n")
        pass