A maya custom node for output motion path with heart shape

heartNode.py

"""A maya custom node for output motion path with heart shape"""

__author__      = 'Huang Weibo <xracz.fx@gmail.com>'
__version__     = '1.0'
__status__      = "release"
__date__        = "2013/3/12"
__copyright__   = "Copyright 2013, riggingtd.com"


import math, sys
import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx

kPluginNodeTypeName = "heartNode"

heartNodeId = OpenMaya.MTypeId(0x1001111)

# Node definition
class HeartNode(OpenMayaMPx.MPxNode):
    # class variables
    aOutX = OpenMaya.MObject()
    aOutY = OpenMaya.MObject()
    aInValue = OpenMaya.MObject()

    
    def __init__(self):
        super(HeartNode,self).__init__()
        
    def compute(self,plug,dataBlock):
        
        if (plug != HeartNode.aOutX and  plug != HeartNode.aOutY):
            return OpenMaya.kUnknownParameter
        
        inputValue = dataBlock.inputValue (HeartNode.aInValue).asFloat()
        
        #heart curve function formula
        outputX = 16*math.pow(math.sin(inputValue),3)
        outputY = 13*math.cos(inputValue) - 5*math.cos(2*inputValue) \
            - 2*math.cos(3*inputValue) - math.cos(4*inputValue)
        
        try:
            hOutputX = dataBlock.outputValue (HeartNode.aOutX)
            hOutputY = dataBlock.outputValue (HeartNode.aOutY)
        except:
            sys.stderr.write ('Failed to get MDataHandle outputValue output')
            raise
        
        hOutputX.setFloat (outputX)
        hOutputX.setClean()
        hOutputY.setFloat (outputY)
        hOutputY.setClean()     
        dataBlock.setClean(plug)
        
        return OpenMaya.MStatus.kSuccess
        

# creator
def nodeCreator():
    return OpenMayaMPx.asMPxPtr( HeartNode() )

# initializer
def nodeInitializer():
    nAttr = OpenMaya.MFnNumericAttribute()
    
    # output    
    HeartNode.aOutX = nAttr.create( "outX", "outX", OpenMaya.MFnNumericData.kFloat, 0.0 )
    nAttr.setWritable (0)
    nAttr.setStorable (0)
    HeartNode.addAttribute (HeartNode.aOutX)

    HeartNode.aOutY = nAttr.create( "outY", "outY", OpenMaya.MFnNumericData.kFloat, 0.0 )
    nAttr.setWritable (0)
    nAttr.setStorable (0)
    HeartNode.addAttribute (HeartNode.aOutY)
    
    # input
    HeartNode.aInValue = nAttr.create( "inValue", "inValue", OpenMaya.MFnNumericData.kFloat, 0.0 )
    nAttr.setKeyable (1)
    HeartNode.addAttribute (HeartNode.aInValue)
    HeartNode.attributeAffects (HeartNode.aInValue, HeartNode.aOutX)
    HeartNode.attributeAffects (HeartNode.aInValue, HeartNode.aOutY)
    
    return OpenMaya.MStatus.kSuccess
    
    
# initialize the script plug-in
def initializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject)
    try:
        mplugin.registerNode( kPluginNodeTypeName, heartNodeId, nodeCreator, nodeInitializer )
    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( heartNodeId )
    except:
        sys.stderr.write( "Failed to deregister node: %s" % kPluginNodeTypeName )
        raise