How to add edge in mesh using Maya Python API 2.0

Question

I use maya.api.OpenMaya.MFnMesh.subdivideEdges() function. Edges are split by vertex, but corresponding new edges does not comming. How can I add edge across the split edges ? or how can I create the edges from one vertex to another. Using Maya Python API 2.0 ?

#This is my Maya Python API 2.0 Code

import maya.api.OpenMaya as om
verticePos      = [(-0.5, -0.5, 0.5, 1), (0.5, -0.5, 0.5, 1), (-0.5, 0.910894, 0.5, 1), (0.5, 0.910894, 0.5, 1), (-0.5, 0.910894, -0.383361, 1), (0.5, 0.910894, -0.383361, 1), (-0.5, -0.5, -0.383361, 1), (0.5, -0.5, -0.383361, 1), -0.5, -0.5, 1.06715, 1), (0.5, -0.5, 1.06715, 1), (0.5, 0.910894, 1.06715, 1), (-0.5, 0.910894, 1.06715, 1), (-0.5, -1.12433, -0.383361, 1), (0.5, -1.12433, -0.383361, 1), (0.5, -1.12433, 0.5, 1), (-0.5, -1.12433, 0.5, 1), (0, 0.910894, 1.06715, 1), (0, 0.910894, 0.5, 1), (0, 0.910894, -0.383361, 1), (0, -0.5, -0.383361, 1), (0, -1.12433, -0.383361, 1), (0, -1.12433, 0.5, 1), (0, -0.5, 0.5, 1), (0, -0.5, 1.06715, 1)]

polygonCounts   = [4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4]
polygonConnects = [8, 23, 16, 11, 2, 17, 18, 4, 4, 18, 19, 6, 12, 20, 21, 15, 1, 7, 5, 3, 6, 0, 2, 4, 0, 22, 23, 8, 1, 3, 10, 9, 17, 2, 11, 16, 2, 0, 8, 11, 6, 19, 20, 12, 7, 1, 14, 13, 22, 0, 15, 21, 0, 6, 12, 15, 3, 17, 16, 10, 18, 17, 3, 5, 19, 18, 5, 7, 20, 19, 7, 13, 21, 20, 13, 14, 1, 22, 21, 14, 23, 22, 1, 9, 16, 23, 9, 10]

uValues         = [0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625]
vValues         = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

#Convert to MPointArray
vertices        = om.MPointArray ()
for eachPos in verticePos :            
    mPoint      = om.MPoint ()            
    mPoint.x    = eachPos[0]      
    mPoint.y    = eachPos[1]      
    mPoint.z    = eachPos[2]              
    vertices.append (mPoint)

mfnMesh    = om.MFnMesh ()
mfnMesh.create(vertices, polygonCounts, polygonConnects, uValues, vValues)
mfnMesh.updateSurface ()
cmds.sets (mfnMesh.fullPathName(), e=1, fe='initialShadingGroup')
mfnMesh.updateSurface()

#Spliting Edges################################
edgeIDs     = [5,7,19,14,12,32,15,17]
mfnMesh.subdivideEdges (edgeIDs, 1)

Answer 1

use OpenMaya.MFnMesh.split(). MFnMesh.split, needed info:

[in]    placements  array that contains elements of the SplitPlacement enumeration. They represent where to place the new vertices for the split.
[in]    edgeList    array of edge IDs to be split, in order of their appearance in the split. There must be as many elements in this array as there are SplitPlacement::kOnEdge elements in the placements array.
[in]    edgeFactors     array of factors in the range [0,1] that represent how far along each edge must the split be done. This array must have the same number of elements as the edgeList array.
[in]    internalPoints  array of positions for the vertices that will be added inside existing faces. There must be as many elements in this array as there are SplitPlacement::kInternalPoint elements in the placements array. This array can be empty. Internal points should be specified on the face between the previous edge id and the next edge id.

working example: check the split method here: Github, accurate way for attribute collecting and clean spliting.

import maya.api.OpenMaya as om
verticePos      = [(-0.5, -0.5, 0.5, 1), (0.5, -0.5, 0.5, 1), (-0.5, 0.910894, 0.5, 1), (0.5, 0.910894, 0.5, 1), (-0.5, 0.910894, -0.383361, 1), (0.5, 0.910894, -0.383361, 1), (-0.5, -0.5, -0.383361, 1), (0.5, -0.5, -0.383361, 1), -0.5, -0.5, 1.06715, 1), (0.5, -0.5, 1.06715, 1), (0.5, 0.910894, 1.06715, 1), (-0.5, 0.910894, 1.06715, 1), (-0.5, -1.12433, -0.383361, 1), (0.5, -1.12433, -0.383361, 1), (0.5, -1.12433, 0.5, 1), (-0.5, -1.12433, 0.5, 1), (0, 0.910894, 1.06715, 1), (0, 0.910894, 0.5, 1), (0, 0.910894, -0.383361, 1), (0, -0.5, -0.383361, 1), (0, -1.12433, -0.383361, 1), (0, -1.12433, 0.5, 1), (0, -0.5, 0.5, 1), (0, -0.5, 1.06715, 1)]

polygonCounts   = [4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4]
polygonConnects = [8, 23, 16, 11, 2, 17, 18, 4, 4, 18, 19, 6, 12, 20, 21, 15, 1, 7, 5, 3, 6, 0, 2, 4, 0, 22, 23, 8, 1, 3, 10, 9, 17, 2, 11, 16, 2, 0, 8, 11, 6, 19, 20, 12, 7, 1, 14, 13, 22, 0, 15, 21, 0, 6, 12, 15, 3, 17, 16, 10, 18, 17, 3, 5, 19, 18, 5, 7, 20, 19, 7, 13, 21, 20, 13, 14, 1, 22, 21, 14, 23, 22, 1, 9, 16, 23, 9, 10]

uValues         = [0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625, 0.625]
vValues         = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]

#Convert to MPointArray
vertices        = om.MPointArray ()
for eachPos in verticePos :            
    mPoint      = om.MPoint ()            
    mPoint.x    = eachPos[0]      
    mPoint.y    = eachPos[1]      
    mPoint.z    = eachPos[2]              
    vertices.append (mPoint)

mfnMesh    = om.MFnMesh ()
mfnMesh.create(vertices, polygonCounts, polygonConnects, uValues, vValues)
mfnMesh.updateSurface ()
cmds.sets (mfnMesh.fullPathName(), e=1, fe='initialShadingGroup')
mfnMesh.updateSurface()

# OpenMaya.MFnMesh.subdivideEdges() dividing the selected 
# edges(we will get new Vertices/Edges)
# The real challenge is connect the new vertices with each other, in order....
# my solution is hacking the right info and connect the Vertices,
# its based on the correct edge flow/selection...

#find all connected edges per Vertex
def ver_coll(rr):
  dict = {}
  for vertexid in range(rr):
    vIdArray = om1.MIntArray()
    vIdArray.append(vertexid)
    vtxCom = om1.MFnSingleIndexedComponent()
    vtxCom.create(om1.MFn.kMeshVertComponent)
    vtxCom.addElements(vIdArray)
    sel = om1.MSelectionList()
    sel.clear()
    sel.add(mfnMesh.fullPathName())
    meshdag = om1.MDagPath()
    sel.getDagPath(0,meshdag)
    vtxIter = om1.MItMeshVertex(meshdag,vtxCom.object())
    vtxIter.getConnectedEdges(vIdArray)
    util = om1.MScriptUtil(vIdArray)
    data = util.asIntPtr()
    numCE = vIdArray.length()
    dict[vertexid] = [util.getIntArrayItem(data, i) for i in range(numCE)]
  return dict

pre = ver_coll(cmds.polyEvaluate(mfnMesh.fullPathName(), v=True))
edgeIDs = [0, 21, 13, 11, 9, 6, 4, 2] # or [5,7,19,14,12,32,15,17] 
mfnMesh.subdivideEdges(edgeIDs, 1)
post = ver_coll(cmds.polyEvaluate(mfnMesh.fullPathName(), v=True))

object_id = mfnMesh.fullPathName().split("|")[1]

for e in range(0,len(edgeIDs),1):
  con = edgeIDs[e:e+2]
  vtx_ids = []
  for c in con:
    for v in set(post.keys())-set(pre.keys()):
      if c in post[v]:
        vtx_ids.append(v)
  if len(vtx_ids) == 2:
    print vtx_ids 
    cmds.polyConnectComponents("{0}.vtx[{1}]".format(object_id, vtx_ids[0]), "{0}.vtx[{1}]".format(object_id, vtx_ids[1]), adjustEdgeFlow=True, ch=True)
  else:
    vtx = []
    for i in [edgeIDs[0], con[0]]:
      for v in set(post.keys())-set(pre.keys()):
        if i in post[v]:
          vtx.append(v)
    cmds.polyConnectComponents("{0}.vtx[{1}]".format(object_id, vtx[0]), "{0}.vtx[{1}]".format(object_id, vtx[1]), adjustEdgeFlow=True, ch=True)