MFnSingleIndexedComponent addElement doesn't work in Maya 2022

[SirDinadan]

I updated to Maya 2022 and run through my old python scripts and some of them failed to produce the same output. I reproduced the issue with a simple example. Basically, I cannot produce a MItMeshPolygon iterator from a MFnSingleIndexedComponent.

python code:

import maya.cmds as cmds
import maya.OpenMaya as om
import maya.OpenMayaMPx as omMPx
import math

cmds.polyPlane( n='myPlane', sx=2, sy=2, w=10, h=10)
selection_list = om.MSelectionList()
dag_path = om.MDagPath()
component = om.MObject()
om.MGlobal.getActiveSelectionList(selection_list)
selection_list.getDagPath(0, dag_path, component)
mItVtx = om.MItMeshVertex( dag_path )

 # set up some scripting junk
intPx = om.MScriptUtil()
intPx.createFromInt(0)
intPtr = intPx.asIntPtr()

while not mItVtx.isDone():
	vtxId = mItVtx.index()
	point = mItVtx.position(om.MSpace.kWorld)
	print('vtxId: ' + str(vtxId))
	print(str(point.x) + ' ' + str(point.y) + ' ' + str(point.z))
	faceList = om.MIntArray()
	mItVtx.getConnectedFaces(faceList)
	print('getConnectedFaces: ' + str(faceList))
	mFnCompFace = om.MFnSingleIndexedComponent()
	compFace = mFnCompFace.create(om.MFn.kMeshPolygonComponent)
	map(mFnCompFace.addElement, faceList)
	check = om.MIntArray()
	mFnCompFace.getElements(check)
	print('check: ' + str(check))
	mItPoly = om.MItMeshPolygon( dag_path, compFace )
	while not mItPoly.isDone():
		point = mItPoly.center()
		mItPoly.numTriangles(intPtr)
		print('\tfaceId: ' + str(mItPoly.index()))
		print('\tnumTriangles: ' + str(om.MScriptUtil(intPtr).asInt()))
		print('\tfaceCtr: ' + str(point.x) + ' ' + str(point.y) + ' ' + str(point.z))
		mItPoly.next()
	mItVtx.next()

maya 2018 output:

vtxId: 0
-5.0 -1.11022302463e-15 5.0
getConnectedFaces: [0]
check: [0]
	faceId: 0
	numTriangles: 2
	faceCtr: -2.5 -5.55111512313e-16 2.5
vtxId: 1
0.0 -1.11022302463e-15 5.0
getConnectedFaces: [0, 1]
check: [0, 1]
	faceId: 0
	numTriangles: 2
	faceCtr: -2.5 -5.55111512313e-16 2.5
	faceId: 1
	numTriangles: 2
	faceCtr: 2.5 -5.55111512313e-16 2.5
vtxId: 2
5.0 -1.11022302463e-15 5.0
getConnectedFaces: [1]
check: [1]
	faceId: 1
	numTriangles: 2
	faceCtr: 2.5 -5.55111512313e-16 2.5
vtxId: 3
-5.0 0.0 0.0
getConnectedFaces: [2, 0]
check: [0, 2]
	faceId: 0
	numTriangles: 2
	faceCtr: -2.5 -5.55111512313e-16 2.5
	faceId: 2
	numTriangles: 2
	faceCtr: -2.5 5.55111512313e-16 -2.5
vtxId: 4
0.0 0.0 0.0
getConnectedFaces: [3, 1, 0, 2]
check: [0, 1, 2, 3]
	faceId: 0
	numTriangles: 2
	faceCtr: -2.5 -5.55111512313e-16 2.5
	faceId: 1
	numTriangles: 2
	faceCtr: 2.5 -5.55111512313e-16 2.5
	faceId: 2
	numTriangles: 2
	faceCtr: -2.5 5.55111512313e-16 -2.5
	faceId: 3
	numTriangles: 2
	faceCtr: 2.5 5.55111512313e-16 -2.5
vtxId: 5
5.0 0.0 0.0
getConnectedFaces: [1, 3]
check: [1, 3]
	faceId: 1
	numTriangles: 2
	faceCtr: 2.5 -5.55111512313e-16 2.5
	faceId: 3
	numTriangles: 2
	faceCtr: 2.5 5.55111512313e-16 -2.5
vtxId: 6
-5.0 1.11022302463e-15 -5.0
getConnectedFaces: [2]
check: [2]
	faceId: 2
	numTriangles: 2
	faceCtr: -2.5 5.55111512313e-16 -2.5
vtxId: 7
0.0 1.11022302463e-15 -5.0
getConnectedFaces: [3, 2]
check: [2, 3]
	faceId: 2
	numTriangles: 2
	faceCtr: -2.5 5.55111512313e-16 -2.5
	faceId: 3
	numTriangles: 2
	faceCtr: 2.5 5.55111512313e-16 -2.5
vtxId: 8
5.0 1.11022302463e-15 -5.0
getConnectedFaces: [3]
check: [3]
	faceId: 3
	numTriangles: 2
	faceCtr: 2.5 5.55111512313e-16 -2.5

maya 2022 output:

vtxId: 0
-5.0 0.0 5.0
getConnectedFaces: [0]
check: []
vtxId: 1
0.0 0.0 5.0
getConnectedFaces: [0, 1]
check: []
vtxId: 2
5.0 0.0 5.0
getConnectedFaces: [1]
check: []
vtxId: 3
-5.0 0.0 0.0
getConnectedFaces: [2, 0]
check: []
vtxId: 4
0.0 0.0 0.0
getConnectedFaces: [3, 1, 0, 2]
check: []
vtxId: 5
5.0 0.0 0.0
getConnectedFaces: [1, 3]
check: []
vtxId: 6
-5.0 0.0 -5.0
getConnectedFaces: [2]
check: []
vtxId: 7
0.0 0.0 -5.0
getConnectedFaces: [3, 2]
check: []
vtxId: 8
5.0 0.0 -5.0
getConnectedFaces: [3]
check: []

Is this a bug or am I doing something wrong? Thank you!

[cheng_xi_li · Accepted solution]

Hi,

In Python 3, map values are evaluated only when it is needed. 

e.g.

#get an iterator
iter = map(mFnCompFace.addElement, faceList)
#use next
next(iter)

If you want to get them directly, you can convert them to a list

e.g.

_result=list(map(mFnCompFace.addElement, faceList))

And you should be able to get the same result as before.

Yours,

Li

[SirDinadan]

Thanks a lot!