Hi guys! I am learning the maya python api and have been trying to write a
deformer that will offset vertices in the direction of there given
velocity. Currently it is doing absolutley nothing, and i cant seem to
figure out why. Any tips would be really helpfull for a beginner :)
Cheers guys! The code is attatched below .
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import math
import sys
import maya.OpenMaya as OpenMaya
import maya.OpenMayaAnim as OpenMayaAnim
import maya.OpenMayaMPx as OpenMayaMPx
import maya.cmds as cmds
kPluginNodeTypeName = "velocityDeformer"
velocityDeformerId = OpenMaya.MTypeId(0x8731)
outputGeom = OpenMayaMPx.cvar.MPxGeometryFilter_outputGeom
envelope = OpenMayaMPx.cvar.MPxGeometryFilter_envelope
## Node definition ##
class velocityDeformer(OpenMayaMPx.MPxDeformerNode):
aTime = OpenMaya.MObject()
def __init__(self):
OpenMayaMPx.MPxDeformerNode.__init__(self)
self._initialized = False
self._previousPosition = OpenMaya.MPointArray()
self._previousTime = OpenMaya.MTime()
def deform(self, dataBlock, geomIter, matrix, multiIndex):
## get input mesh point array ##
inputAttribute = OpenMayaMPx.cvar.MPxGeometryFilter_input
inputGeom = OpenMayaMPx.cvar.MPxGeometryFilter_inputGeom
hInput = dataBlock.outputArrayValue(inputAttribute)
hInput.jumpToElement(multiIndex)
oInputGeom = hInput.outputValue().child(inputGeom).asMesh()
fnInputMesh = OpenMaya.MFnMesh(oInputGeom)
input_points = OpenMaya.MPointArray()
fnInputMesh.getPoints(input_points)
## get time ##
currentTime = OpenMayaAnim.MAnimControl.currentTime()
## get envelope ##
envelopeHandle = dataBlock.inputValue(envelope)
envelopeValue = envelopeHandle.asFloat()
## get multiplier ##
multiplier =
dataBlock.inputValue(velocityDeformer.aMultiplier).asFloat()
## Initialize the data ##
if not self._initialized:
self._previousTime = currentTime
self._previousPosition = input_points
self._initialized = True
while geomIter.isDone() == False:
point = geomIter.position()
time = self._previousTime - OpenMayaAnim.MAnimControl.currentTime()
velocity = (point - self._previousPosition[geomIter.index()]) / time
newPosition = point + (velocity * multiplier)
input_points[geomIter.index()] = newPosition
point = newPosition * envelopeValue
geomIter.setPosition(point)
geomIter.next()
self._previousPosition = OpenMaya.MPointArray(input_points)
self._previousTime = OpenMayaAnim.MAnimControl.currentTime()
## creator ##
def nodeCreator():
return OpenMayaMPx.asMPxPtr(velocityDeformer())
## initializer ##
def nodeInitializer():
nAttr = OpenMaya.MFnNumericAttribute()
velocityDeformer.aMultiplier = nAttr.create('Multiplier', 'mp',
OpenMaya.MFnNumericData.kFloat)
nAttr.setKeyable(True)
velocityDeformer.addAttribute(velocityDeformer.aMultiplier)
velocityDeformer.attributeAffects(velocityDeformer.aMultiplier, outputGeom)
## initialize the script plug-in ##
def initializePlugin(mobject):
mplugin = OpenMayaMPx.MFnPlugin(mobject)
try:
mplugin.registerNode(kPluginNodeTypeName, velocityDeformerId,
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(velocityDeformerId)
except:
sys.stderr.write("Failed to unregister node: %s\n" %
kPluginNodeTypeName)
