scripted/yTwistNode.py

#-
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#+

########################################################################
# DESCRIPTION:
#
# Produces the dependency graph node "spyTwistNode".
#
# This plug-in demonstrates how to create a user-defined deformer.
# A deformer is a node which takes any number of input geometries, deforms them,
# and places the output into the output geometry attribute. This example plug-in
# defines a new deformer node that twists the deformed vertices of the input
# around the y-axis.
#
# To use this node: 
#
#   (1) Load the plug-in and create a sphere (or some other object):
#
#       import maya
#       maya.cmds.loadPlugin("yTwistNode.py")
#       maya.cmds.sphere()
#
#   (2) Select the sphere, and then enter the command:
#
#       maya.cmds.deformer( type='spyTwistNode' )
#
# Bring up the channel box and select the spyTwistNode1 input.
# You can change the Angle value to deform the geometry.
#
########################################################################

import math, sys

import maya.OpenMaya as OpenMaya
import maya.OpenMayaAnim as OpenMayaAnim
import maya.OpenMayaMPx as OpenMayaMPx
import maya.cmds as cmds

kPluginNodeTypeName = "spyTwistNode"

yTwistNodeId = OpenMaya.MTypeId(0x8702)

kApiVersion = cmds.about(apiVersion=True)
if kApiVersion < 201600:
    outputGeom = OpenMayaMPx.cvar.MPxDeformerNode_outputGeom
    envelope = OpenMayaMPx.cvar.MPxDeformerNode_envelope
else:
    outputGeom = OpenMayaMPx.cvar.MPxGeometryFilter_outputGeom
    envelope = OpenMayaMPx.cvar.MPxGeometryFilter_envelope

# Node definition
class yTwistNode(OpenMayaMPx.MPxDeformerNode):
    # class variables
    angle = OpenMaya.MObject()
    # constructor
    def __init__(self):
        OpenMayaMPx.MPxDeformerNode.__init__(self)
    # deform
    def deform(self,dataBlock,geomIter,matrix,multiIndex):
        #
        # get the angle from the datablock
        angleHandle = dataBlock.inputValue( self.angle )
        angleValue = angleHandle.asDouble()
        #
        # get the envelope
        envelopeHandle = dataBlock.inputValue( envelope )
        envelopeValue = envelopeHandle.asFloat()
        #
        # iterate over the object and change the angle
        while geomIter.isDone() == False:
            point = geomIter.position()
            ff = angleValue * point.y * envelopeValue
            if ff != 0.0:
                cct= math.cos(ff)
                cst= math.sin(ff)
                tt= point.x*cct-point.z*cst
                point.z= point.x*cst + point.z*cct
                point.x=tt
            geomIter.setPosition( point )
            geomIter.next()
                
# creator
def nodeCreator():
    return OpenMayaMPx.asMPxPtr( yTwistNode() )

# initializer
def nodeInitializer():
    # angle
    nAttr = OpenMaya.MFnNumericAttribute()
    yTwistNode.angle = nAttr.create( "angle", "fa", OpenMaya.MFnNumericData.kDouble, 0.0 )
    #nAttr.setDefault(0.0)
    nAttr.setKeyable(True)
    # add attribute
    try:
        yTwistNode.addAttribute( yTwistNode.angle )
        yTwistNode.attributeAffects( yTwistNode.angle, outputGeom )
    except:
        sys.stderr.write( "Failed to create attributes of %s node\n", kPluginNodeTypeName )
    
# initialize the script plug-in
def initializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject)
    try:
        mplugin.registerNode( kPluginNodeTypeName, yTwistNodeId, nodeCreator, nodeInitializer, OpenMayaMPx.MPxNode.kDeformerNode )
    except:
        sys.stderr.write( "Failed to register node: %s\n" % kPluginNodeTypeName )

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