Grow Skin Weights from selected vertices to adjacent vertices

GrowSkinWeights

import maya.api.OpenMaya as om2
import maya.api.OpenMayaAnim as oma2
import maya.cmds as mc

class growSkinWeights(object):
	
	def __init__(self):
		self.cIds = None
		
	def growSkinDo(self, mode):
		selVerts = om2.MGlobal.getActiveSelectionList()
		# Get selected verts indices
		if selVerts.length() == 0:
			mc.warning('Please, select any vertex')
			return
		dp, comp = selVerts.getComponent(0)
		compFn = om2.MFnSingleIndexedComponent(comp)
		if comp.isNull():
			mc.warning('Please, select any vertex')
			return
		ids = compFn.getElements()
		if mode == 'copy':
			self.cIds = ids
		else:
			# Get all mesh vertices and edges count
			numVertices = om2.MFnMesh( dp ).numVertices
			numEdges = om2.MFnMesh( dp ).numEdges
			# Get skinCluster from the mesh
			self.skinCl = mc.ls( mc.listHistory( dp, pdo=1, il=2 ), typ='skinCluster' )
			if self.skinCl and self.cIds is not None:
				# Convert skinCluster to MFnSkinCluster to be able extract influences and weights from it
				self.skinFn = oma2.MFnSkinCluster( om2.MSelectionList().add( self.skinCl[0] ).getDependNode(0) )
				# get the MDagPath for all influence
				infDags = self.skinFn.influenceObjects()
				self.allInfs = infDags
				self.infIds = {}
				for x in xrange(infDags.__len__()):
					infPath = infDags[x].fullPathName()
					infId = int(self.skinFn.indexForInfluenceObject(infDags[x]))
					self.infIds[x] = infId
					# unlock influences used by skincluster
					mc.setAttr('%s.liw' % infPath)
				# get the MPlug for the weightList and weights attributes
				self.wlPlug = self.skinFn.findPlug( 'weightList',0 )
				self.wPlug = self.skinFn.findPlug( 'weights',0 )
				self.wlAttr = self.wlPlug.attribute()
				self.wAttr = self.wPlug.attribute()
				# Get selected and unselected vertices that share the same edge
				idsShareEdge = {}
				meshEdgeIt = om2.MItMeshEdge( dp )
				for e in xrange(numEdges):
					meshEdgeIt.setIndex(e)
					vertEdgeId = ( meshEdgeIt.vertexId(0), meshEdgeIt.vertexId(1) )
					if vertEdgeId[0] in self.cIds and vertEdgeId[1] in ids:
						#print vertEdgeId[0], vertEdgeId[1]
						self.setGrowSkinWeights( vertEdgeId[0], vertEdgeId[1] )
					elif vertEdgeId[1] in self.cIds and vertEdgeId[0] in ids:
						#print vertEdgeId[1], vertEdgeId[0]
						self.setGrowSkinWeights( vertEdgeId[1], vertEdgeId[0] )
			else:
				mc.warning( 'Something went wrong, please copy skin weights again' )
	def setGrowSkinWeights( self, origVert, affectVert ):
		vWeights = {}
		# tell the weights attribute which vertex id it represents
		self.wPlug.selectAncestorLogicalIndex(origVert, self.wlAttr)
		# get the indice of all non-zero weights for this vert
		wInfIds = self.wPlug.getExistingArrayAttributeIndices()
		# create a copy of the current wPlug
		infPlug = om2.MPlug(self.wPlug)
		for infId in xrange(len(self.allInfs)):
			# tell the infPlug it represents the current influence id
			infPlug.selectAncestorLogicalIndex(self.infIds[infId], self.wAttr)
			# add this influence and its weight to this verts weights
			if infId in self.infIds.keys():
				mc.setAttr( '%s.weightList[%s].weights[%s]' %( self.skinCl[0], affectVert, self.infIds[infId] ), infPlug.asDouble() )
			else:
				infNum = int(self.skinFn.indexForInfluenceObject(self.allInfs[infId]))
				mc.setAttr( '%s.weightList[%s].weights[%s]' %( self.skinCl[0], affectVert, infNum ), 0 )

gr = growSkinWeights()
gr.growSkinDo('copy')
#gr.growSkinDo('paste')