Get skincluster data with maya’s python API

The code below demonstrates, via maya’s python api, how to retrieve:
– mObject from a mesh, and its skincluster
– MFnSkinCluster for the skincluster on that mesh
– the influences in that skin cluster and their names
– the influence weights for every vert in that mesh
Enjoy!

# Imports first!
# Don‘t mind the short names, I have a habit of using mc, om, oma for maya‘s modules
import maya.OpenMaya as om
import maya.OpenMayaAnim as oma

Next, we’ll get the MObject & MDagPath for our mesh’s shapenode

# The shape node for some mesh
mesh = ‘pSphereShape1‘
mSel = om.MSelectionList()
mSel.add(mesh)
meshMObject = om.MObject()
meshDagPath  = om.MDagPath()
mSel.getDependNode(0, meshMObject)
mSel.getDagPath(0, meshDagPath)

Next, an MDagPathArray of the influences and the influence count.
Also, the node names for those influences, for convenience.

# Influences & Influence count
influences= om.MDagPathArray()
infCount = skinFn.influenceObjects(influences)
# Get node names for influences
influenceNames = [influences[i].partialPathName() for i in range(infCount)]

Finally, get all of the weight data, organized as a dictionary of dictionaries.
The first level will use vert indices for keys, the next will be a dict of influence name : weight.

weightData = {} # Ordered by vertIter 0-numVerts
vertIter = om.MItGeometry(meshMObject)
while not vertIter.isDone():
    vertInfCount = om.MScriptUtil()
    vertInfCountPtr = vertInfCount.asUintPtr()
    om.MScriptUtil.setUint(vertInfCountPtr, 0)
    weights = om.MDoubleArray()
    skinFn.getWeights(meshDagPath,
                      vertIter.currentItem(),
                      weights,
                      vertInfCountPtr)
    # Create a dictionary for each vert index in the mesh
    # All influences will be returned for each vert, but may have 0 influence
    weightData[vertIter.index()] = dict(zip(influenceNames, weights))
    vertIter.next()