scripted/slopeShader.py

#-
# ==========================================================================
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########################################################################
# DESCRIPTION:
#
# Produces the dependency graph node "spSlopeShader".
#
# This plug-in implements a Maya software shader in Python. An angle attribute
# is used to define the space on the object that is being shaded, which is both
# walkable and non-walkable. The walkable and non-walkable colors are set as 
# attributes on the node. The shader will render both the walkable and non-walkable
# areas based on the color that has been set.
#
# To use:
#
#   (1) Load the slopeShader.py plug-in into Maya.
#   
#       import maya
#       maya.cmds.loadPlugin("slopeShader.py")
#
#   (2) Create a polygon sphere.
#   (3) Assign a shader to the sphere.
#   (4) Open the Attribute Editor > Color Channel > Utilities > spSlopeShader to apply
#       the texture on the sphere.
#   (5) Render the scene to view the results.
#
# The angle attribute can be adjusted to see different results.
#
########################################################################

# imports
import maya.OpenMaya as OpenMaya
import maya.OpenMayaUI as OpenMayaUI
import maya.OpenMayaMPx as OpenMayaMPx
import math, sys

# consts
kSlopeShaderBehaviourName = "slopeShaderBehaviour"
kSlopeNodeName = "spSlopeShader"
kSlopeNodeClassify = "utility/color"
kSlopeNodeId = OpenMaya.MTypeId(0x87001)

# Node definition
class slopeShader(OpenMayaMPx.MPxNode):
    # class variables
    aAngle = OpenMaya.MObject()
    aColor1 = OpenMaya.MObject()
    aColor2 = OpenMaya.MObject()
    aTriangleNormalCamera = OpenMaya.MObject()
    aOutColor = OpenMaya.MObject()
    aMatrixEyeToWorld = OpenMaya.MObject()
    aDirtyShaderAttr = OpenMaya.MObject()

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


    def compute(self, plug, dataBlock):
        if plug == slopeShader.aOutColor or plug.parent() == slopeShader.aOutColor:

            resultColor = OpenMaya.MFloatVector(0.0,0.0,0.0)

            try:
                dataHandle = dataBlock.inputValue( slopeShader.aColor1 )
            except:
                sys.stderr.write( "Failed to get inputValue aColor1" )
                raise
            walkable = dataHandle.asFloatVector()

            try:
                dataHandle = dataBlock.inputValue( slopeShader.aColor2 )
            except:
                sys.stderr.write( "Failed to get inputValue aColor2" )
                raise
            nonWalkable = dataHandle.asFloatVector()

            try:
                dataHandle = dataBlock.inputValue( slopeShader.aTriangleNormalCamera )
            except:
                sys.stderr.write( "Failed to get inputValue aTriangleNormalCamera" )
                raise
            surfaceNormal = dataHandle.asFloatVector()

            try:
                dataHandle = dataBlock.inputValue( slopeShader.aMatrixEyeToWorld )
            except:
                sys.stderr.write( "Failed to get inputValue aMatrixEyeToWorld" )
                raise
            viewMatrix = dataHandle.asFloatMatrix()

            # Get the angle
            try:
                dataHandle = dataBlock.inputValue( slopeShader.aAngle )
            except:
                sys.stderr.write( "Failed to get inputValue aAngle" )
                raise
            angle = dataHandle.asFloat()

            yVector = OpenMaya.MFloatVector(0, 1, 0)

            # Normalize the view vector
            #
            surfaceNormal.normalize()
            WSVector = surfaceNormal * viewMatrix

            # find dot product
            #
            scalarNormal = WSVector * yVector

            # take the absolute value
            #
            if scalarNormal < 0.0:
                scalarNormal *= -1.0

            radianAngle = math.radians(angle)
            cosOfAngle = math.cos(radianAngle)
            if cosOfAngle < scalarNormal:
                resultColor = walkable
            else:
                resultColor = nonWalkable

            # set output color attribute
            #
            try:
                outColorHandle = dataBlock.outputValue( slopeShader.aOutColor )
            except:
                sys.stderr.write( "Failed to get outputValue aOutColor" )
                raise

            outColorHandle.setMFloatVector(resultColor)
            outColorHandle.setClean()

        else:
            return OpenMaya.kUnknownParameter


    def postConstructor(self):
        print "In slopeShader.postConstructor"
        # OpenMayaMPx.MPxNode.setMPSafe(self, 1)


class slopeShaderBehavior(OpenMayaMPx.MPxDragAndDropBehavior):
    def __init__(self):
        OpenMayaMPx.MPxDragAndDropBehavior.__init__(self)


    def shouldBeUsedFor(self, sourceNode, destinationNode, sourcePlug, destinationPlug):
        """
        Overloaded function from MPxDragAndDropBehavior
        this method will return True if it is going to handle the connection
        between the two nodes given.
        """
        result = False

        if sourceNode.hasFn(OpenMaya.MFn.kLambert):
            #if the source node was a lambert
            #than we will check the downstream connections to see 
            #if a slope shader is assigned to it.
            #
            shaderNode = None
            src = OpenMaya.MFnDependencyNode(sourceNode)
            connections = OpenMaya.MPlugArray()
            src.getConnections(connections)

            for i in range(connections.length()):
                #check the incoming connections to this plug
                #
                connectedPlugs = OpenMaya.MPlugArray()
                connections[i].connectedTo(connectedPlugs, True, False)
                for j in range(connectedPlugs.length()):
                    #if the incoming node is a slope shader than 
                    #set shaderNode equal to it and break out of the inner 
                    #loop
                    #
                    testNode = OpenMaya.MFnDependencyNode(connectedPlugs[j].node())
                    if testNode.typeName() == kSlopeNodeName:
                        shaderNode = connectedPlugs[j].node()
                        break

                #if the shaderNode is not None
                #than we have found a slopeShader
                #
                if shaderNode is not None:
                    #if the destination node is a mesh than we will take
                    #care of this connection so set the result to True
                    #and break out of the outer loop
                    #
                    if destinationNode.hasFn(OpenMaya.MFn.kMesh):
                        result = True
                    break

        node = OpenMaya.MFnDependencyNode(sourceNode)
        if node.typeName() == kSlopeNodeName:
            #if the sourceNode is a slope shader than check what we
            #are dropping on to
            #
            if destinationNode.hasFn(OpenMaya.MFn.kLambert):
                result = True
            elif destinationNode.hasFn(OpenMaya.MFn.kMesh):
                result = True

        return result


    def connectNodeToNode(self, sourceNode, destinationNode, force):
        """
        Overloaded function from MPxDragAndDropBehavior
        this method will handle the connection between the slopeShader and the shader it is
        assigned to as well as any meshes that it is assigned to.
        """
        src = OpenMaya.MFnDependencyNode(sourceNode)

        #if we are dragging from a lambert
        #we want to check what we are dragging
        #onto.
        if sourceNode.hasFn(OpenMaya.MFn.kLambert):
            shaderNode = OpenMaya.MObject()
            connections = OpenMaya.MPlugArray()
            shaderNodes = OpenMaya.MObjectArray()
            shaderNodes.clear()

            #if the source node was a lambert
            #than we will check the downstream connections to see 
            #if a slope shader is assigned to it.
            #
            src.getConnections(connections)
            for i in range(connections.length()):
                #check the incoming connections to this plug
                #
                connectedPlugs = OpenMaya.MPlugArray()
                connections[i].connectedTo(connectedPlugs, True, False)
                for j in range(connectedPlugs.length()):
                    #if the incoming node is a slope shader than 
                    #append the node to the shaderNodes array
                    #
                    currentnode = connectedPlugs[j].node()
                    if OpenMaya.MFnDependencyNode(currentnode).typeName() == kSlopeNodeName:
                        shaderNodes.append(currentnode)

            #if we found a shading node
            #than check the destination node 
            #type to see if it is a mesh
            #
            if shaderNodes.length() > 0:
                dest = OpenMaya.MFnDependencyNode(destinationNode)
                if destinationNode.hasFn(OpenMaya.MFn.kMesh):
                    #if the node is a mesh than for each slopeShader
                    #connect the worldMesh attribute to the dirtyShaderPlug
                    #attribute to force an evaluation of the node when the mesh
                    #changes
                    #
                    for i in range(shaderNodes.length()):
                        srcPlug = dest.findPlug("worldMesh")
                        destPlug = OpenMaya.MFnDependencyNode(shaderNodes[i]).findPlug("dirtyShaderPlug")

                        if (not srcPlug.isNull()) and (not destPlug.isNull()):
                            cmd = "connectAttr -na %s %s" % (srcPlug.name(), destPlug.name())
                            OpenMaya.MGlobal.executeCommand(cmd)

                    #get the shading engine so we can assign the shader
                    #to the mesh after doing the connection
                    #
                    shadingEngine = self._findShadingEngine(sourceNode)

                    #if there is a valid shading engine than make
                    #the connection
                    #
                    if not shadingEngine.isNull():
                        cmd = "sets -edit -forceElement %s %s" % (
                                        OpenMaya.MFnDependencyNode(shadingEngine).name(),
                                        OpenMaya.MFnDagNode(destinationNode).partialPathName()
                                                                )
                        OpenMaya.MGlobal.executeCommand(cmd)

        elif src.typeName() == kSlopeNodeName:
            #if we are dragging from a slope shader
            #than we want to see what we are dragging onto
            #
            if destinationNode.hasFn(OpenMaya.MFn.kMesh):
                #if the user is dragging onto a mesh
                #than make the connection from the worldMesh
                #to the dirtyShader plug on the slopeShader
                #
                dest = OpenMaya.MFnDependencyNode(destinationNode)
                srcPlug = dest.findPlug("worldMesh")
                destPlug = src.findPlug("dirtyShaderPlug")
                if (not srcPlug.isNull()) and (not destPlug.isNull()):
                    cmd = "connectAttr -na %s %s" % (srcPlug.name(), destPlug.name())
                    OpenMaya.MGlobal.executeCommand(cmd)

            elif destinationNode.hasFn(OpenMaya.MFn.kLambert):
                dest = OpenMaya.MFnDependencyNode(destinationNode)
                srcPlug = src.findPlug("outColor")
                destPlug = dest.findPlug("color")
                if (not srcPlug.isNull()) and (not destPlug.isNull()):
                    if force:
                        cmd = "connectAttr -f %s %s" % (srcPlug.name(), destPlug.name())
                    else:
                        cmd = "connectAttr %s %s" % (srcPlug.name(), destPlug.name())
                    OpenMaya.MGlobal.executeCommand(cmd)


    def connectNodeToAttr(self, sourceNode, destinationPlug, force):
        """
        Overloaded function from MPxDragAndDropBehavior
        this method will assign the correct output from the slope shader 
        onto the given attribute.
        """
        src = OpenMaya.MFnDependencyNode(sourceNode)

        #if we are dragging from a slopeShader
        #to a shader than connect the outColor
        #plug to the plug being passed in
        #
        if destinationPlug.node().hasFn(OpenMaya.MFn.kLambert):
            if src.typeName() == kSlopeNodeName:
                srcPlug = src.findPlug("outColor")
                if (not srcPlug.isNull()) and (not destinationPlug.isNull()):
                    cmd = "connectAttr %s %s" % (srcPlug.name(), destinationPlug.name())
                    OpenMaya.MGlobal.executeCommand(cmd)
        else:
            #in all of the other cases we do not need the plug just the node
            #that it is on
            #
            destinationNode = destinationPlug.node()
            self.connectNodeToNode(sourceNode, destinationNode, force)


    def _findShadingEngine(self, node):
        """
        Given the material MObject this method will
        return the shading group that it is assigned to.
        if there is no shading group associated with
        the material than a null MObject is passed back.
        """
        nodeFn = OpenMaya.MFnDependencyNode (node)
        srcPlug = nodeFn.findPlug("outColor")
        nodeConnections = OpenMaya.MPlugArray()
        srcPlug.connectedTo(nodeConnections, False, True)
        #loop through the connections
        #and find the shading engine node that
        #it is connected to
        #
        for i in range(nodeConnections.length()):
            theNode = nodeConnections[i].node()
            if theNode.hasFn(OpenMaya.MFn.kShadingEngine):
                return theNode

        #no shading engine associated so return a
        #null MObject
        #
        return OpenMaya.MObject()


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


def nodeCreator():
    return OpenMayaMPx.asMPxPtr(slopeShader())


def behaviourCreator():
    return OpenMayaMPx.asMPxPtr(slopeShaderBehavior())


def nodeInitializer():
    nAttr = OpenMaya.MFnNumericAttribute()
    nMAttr = OpenMaya.MFnMatrixAttribute()
    nTAttr = OpenMaya.MFnTypedAttribute()
    nGAttr = OpenMaya.MFnGenericAttribute()
    # input
    slopeShader.aAngle = nAttr.create( "angle", "ang", OpenMaya.MFnNumericData.kFloat )
    nAttr.setDefault(30.0)
    nAttr.setMin(0.0)
    nAttr.setMax(100.0)
    nAttr.setKeyable(1)
    nAttr.setStorable(1)
    nAttr.setReadable(1)
    nAttr.setWritable(1)

    slopeShader.aColor1 = nAttr.createColor("walkableColor", "w")
    nAttr.setDefault(0.0, 1.0, 0.0)
    nAttr.setKeyable(1)
    nAttr.setStorable(1)
    nAttr.setUsedAsColor(1)
    nAttr.setReadable(1)
    nAttr.setWritable(1)

    slopeShader.aColor2 = nAttr.createColor( "nonWalkableColor", "nw" )
    nAttr.setDefault(1.0, 0.0, 0.0)
    nAttr.setKeyable(1)
    nAttr.setStorable(1)
    nAttr.setUsedAsColor(1)
    nAttr.setReadable(1)
    nAttr.setWritable(1)

    # Surface Normal supplied by the render sampler
    #
    slopeShader.aTriangleNormalCamera = nAttr.createPoint( "triangleNormalCamera", "n" )
    nAttr.setStorable(0)
    nAttr.setHidden(1)
    nAttr.setReadable(1)
    nAttr.setWritable(1)

    # View matrix from the camera into world space
    #
    slopeShader.aMatrixEyeToWorld = nMAttr.create( "matrixEyeToWorld", "mew", OpenMaya.MFnMatrixAttribute.kFloat )
    nAttr.setHidden(1)
    nMAttr.setWritable(1)

    # Output Attributes
    #
    slopeShader.aOutColor  = nAttr.createColor( "outColor", "oc" )
    nAttr.setStorable(0)
    nAttr.setHidden(0)
    nAttr.setReadable(1)
    nAttr.setWritable(0)

    meshTypeId = OpenMaya.MTypeId(OpenMaya.MFnData.kMesh)

    # dummy plug for forcing evaluation
    #
    slopeShader.aDirtyShaderAttr = nGAttr.create( "dirtyShaderPlug", "dsp")
    nGAttr.setArray(1)
    nGAttr.setHidden(0)
    nGAttr.setUsesArrayDataBuilder(1)
    nGAttr.setReadable(0)
    nGAttr.setStorable(1)
    nGAttr.setIndexMatters(0)
    # nGAttr.addAccept(meshTypeId)

    # Add attribues
    #
    slopeShader.addAttribute(slopeShader.aAngle)
    slopeShader.addAttribute(slopeShader.aColor1)
    slopeShader.addAttribute(slopeShader.aColor2)
    slopeShader.addAttribute(slopeShader.aTriangleNormalCamera)
    slopeShader.addAttribute(slopeShader.aOutColor)
    slopeShader.addAttribute(slopeShader.aMatrixEyeToWorld)
    slopeShader.addAttribute(slopeShader.aDirtyShaderAttr)

    slopeShader.attributeAffects (slopeShader.aAngle,  slopeShader.aOutColor)
    slopeShader.attributeAffects (slopeShader.aColor1, slopeShader.aOutColor)
    slopeShader.attributeAffects (slopeShader.aColor2, slopeShader.aOutColor)
    slopeShader.attributeAffects (slopeShader.aTriangleNormalCamera,  slopeShader.aOutColor)
    slopeShader.attributeAffects (slopeShader.aDirtyShaderAttr, slopeShader.aOutColor)


# initialize the script plug-in
def initializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject)

    # register node
    try:
        mplugin.registerNode(kSlopeNodeName, kSlopeNodeId, nodeCreator, nodeInitializer, OpenMayaMPx.MPxNode.kDependNode, kSlopeNodeClassify)
    except:
        sys.stderr.write("Failed to register node: %s" % kSlopeNodeName )
        raise

    # register behaviors
    try:
        mplugin.registerDragAndDropBehavior(kSlopeShaderBehaviourName, behaviourCreator)
    except:
        sys.stderr.write("Failed to register behaviour: %s" % kSlopeShaderBehaviourName)

    postCmd = "if( `window -exists createRenderNodeWindow` )  {refreshCreateRenderNodeWindow(\"%s\");}\n" % kSlopeNodeClassify
    OpenMaya.MGlobal.executeCommand(postCmd)


# uninitialize the script plug-in
def uninitializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject, "Autodesk", "1.0", "Any")
    try:
        mplugin.deregisterNode(kSlopeNodeId)
    except:
        sys.stderr.write( "Failed to unregister node: %s" % kSlopeNodeName )
        raise

    try:
        plugin.deregisterDragAndDropBehavior(kSlopeShaderBehaviourName)
    except:
        sys.stderr.write("Failed to deregister behaviour: %s" % kSlopeShaderBehaviourName)

    postCmd = "if( `window -exists createRenderNodeWindow` )  {refreshCreateRenderNodeWindow(\"%s\");}\n" % kSlopeNodeClassify
    OpenMaya.MGlobal.executeCommand(postCmd)