scripted/customImagePlane.py

#-
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#+

#
# Description: 
#   Demonstrates how to create your own custom image plane based on
#   Maya's internal image plane classes. This allows API users to
#   override the default Maya image plane behavior. This class works
#   like typical API nodes in that it can have a compute method and
#   can contain static attributes added by the API user.  This
#   example class overrides the default image plane behavior and
#   allows users to add transparency to an image plane using the
#   transparency attribute on the node. Note, this code also 
#   illustrates how to use MImage to control the floating point
#   depth buffer.  When useDepthMap is set to true, depth is added
#   is added to the image such that half of the iamge is at the near 
#   clip plane and the remaining half is at the far clip plane. 
#
#   Note, once the image plane node has been created it you must
#   attached it to the camera shape that is displaying the node.
#   Image planes are attached to cameras via the imagePlane message
#   attribute on the camera shape.  To attach this example image
#   plane you should connect the image plane's message attribute to
#   the cameraShapes imagePlane attribute.  Note, the imagePlane
#   attribute is a multi attribute and can hold references to
#   multiple image planes.
#
#   This example works only with renderers that use node evaluation
#   as a part of the rendering process, e.g. Maya Software. It does 
#   not work with renderes that rely on a scene translation mechanism,
#   e.g. mental ray.
#
# Usage:
#
#   Run the script:
#
#   import maya
#   maya.cmds.loadPlugin("customImagePlane.py")
#   imageP = maya.cmds.createNode("spCustomImagePlane")
#   maya.cmds.connectAttr( imageP + ".message", "perspShape.imagePlane[0]", force = True )
#
#   Then assign an image to the customImagePlane node
#

import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx
import sys

kPluginNodeTypeName = "spCustomImagePlane"
kPluginNodeId = OpenMaya.MTypeId(0x87016)

# Node definition
class customImagePlane(OpenMayaMPx.MPxImagePlane):
    # class variables
    aTransparency = OpenMaya.MObject()
    
    # internal variables
    fTransparency = 0.0
            
    def __init__(self):
        OpenMayaMPx.MPxImagePlane.__init__(self)
        
    def getInternalValueInContext( self, plug, handle, context ):
        if plug == self.aTransparency:
            handle.setDouble( self.fTransparency )
            return True
        
        return OpenMayaMPx.MPxImagePlane.getInternalValueInContext( self, plug, handle, context )
    
    def setInternalValueInContext( self, plug, handle, context ):
        if plug == self.aTransparency:
            self.fTransparency = handle.asDouble()
            self.setImageDirty()
            return True
        
        return OpenMayaMPx.MPxImagePlane.setInternalValueInContext( self, plug, handle, context )   
        
    def loadImageMap(self, fileName, frame, image):
        try:    
            image.readFromFile(fileName)
            
            # get the width and height of the image an MScriptUtil is needed
            # to pass in a pointer to the MImage::getSize() method
            widthUtil = OpenMaya.MScriptUtil(0)
            widthPtr = widthUtil.asUintPtr()
            heightUtil = OpenMaya.MScriptUtil(0)
            heightPtr = heightUtil.asUintPtr()
            image.getSize( widthPtr, heightPtr )
            
            width = widthUtil.getUint(widthPtr)
            height = heightUtil.getUint(heightPtr)      
            size = width * height
            
            # Implement transparency
            charPixelPtr = image.pixels()
            for i in range( 0, size, 4 ):
                alphaIndex = (i*4)+3
                alpha = OpenMayaScript.getCharArrayItem(charPixelPtr,alphaIndex)
                OpenMayaScript.setCharArray( alpha * (1.0 - self.fTransparency), alphaIndex )
            
            # Implement use depth map
            thisNode = self.thisMObject()
            fnThisNode = OpenMaya.MFnDependencyNode(thisNode)
            useDepthMap = fnThisNode.attribute("useDepthMap")
            depthMap = OpenMaya.MPlug( thisNode, useDepthMap )
            value = depthMap.asBool()
            
            if value:               
                buffer = []         
                c = 0
                for i in range( 0, height ):
                    for j in range( 0, width ):
                        if i > height/2.0:
                            buffer.insert(c, -1.0)
                        else:
                            buffer.insert(c, 0.0)
                        c+=1
                        
                depthMapArray = OpenMaya.MScriptUtil()
                depthMapArray.createFromList( buffer )
                depthMapArrayFloatPtr = depthMapArray.asFloatPtr()
                image.setDepthMap( depthMapArrayFloatPtr, width, height )
                
        except:
            pass
            
# creator
def nodeCreator():
    return OpenMayaMPx.asMPxPtr( customImagePlane() )
    
# initializer
def nodeInitializer():
    nAttr = OpenMaya.MFnNumericAttribute()

    # Setup the input attributes
    customImagePlane.aTransparency = nAttr.create("transparency", "tp", OpenMaya.MFnNumericData.kDouble, 0.0)
    nAttr.setStorable(True)
    nAttr.setInternal(True)
    nAttr.setMin(0.0)
    nAttr.setMax(1.0)
    nAttr.setKeyable(True)
    
    customImagePlane.addAttribute(customImagePlane.aTransparency)
    
# initialize the script plug-in
def initializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject, "Autodesk", "1.0", "Any")
    try:
        mplugin.registerNode( kPluginNodeTypeName, kPluginNodeId, nodeCreator, nodeInitializer, OpenMayaMPx.MPxNode.kImagePlaneNode )
    except:
        sys.stderr.write( "Failed to register node: %s" % kPluginNodeTypeName )
        raise


# uninitialize the script plug-in
def uninitializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject)
    try:
        mplugin.deregisterNode( kPluginNodeId )
    except:
        sys.stderr.write( "Failed to register node: %s" % kPluginNodeTypeName )
        raise