Hey Michael,
Thank you for the tips on the API and techniques to use for speed.
I was testing out your code and it works great. I am a bit confused though
(I have not managed to wrap my head around how each return list corresponds
to each other yet).
I need border edges for the UV shells. This way I can iterate each uv set,
get the border uvs, check that this particular UVs vertex has not already
been counted and add this to the total vert count rather than each UV.
- Ben
On Friday, 10 November 2017 02:57:06 UTC+1, Michael Boon wrote:
>
> For speed, you definitely want to use OpenMaya, but more importantly,
> avoid creating new Python objects every time you loop over a vert. Try to
> create some lists of regular Python ints upfront, then just count them.
>
> Once you have a MFnMesh, you can get a list of the UV IDs used at each
> corner of each face using MFnMesh.getVertices() and MFnMesh.
> getAssignedUVs().
> polyVertices = fnMesh.getVertices()
> polyUVIDs = fnMesh.getAssignedUVs() # with optional UV set name
> Both those functions return two lists. The first list in each is the list
> of vertex counts in each polygon, which we don't care about. The second
> lists are the vert IDs, and the corresponding UV IDs. It's significant that
> these are corresponding lists, since we're going to zip them together.
>
> Create a list with an entry for each vert in the mesh, then you can put
> the UV IDs each vert uses into its entry in the list. You know the number
> of verts, so you can create the main list in one hit, for speed. By using
> sets, you only record the unique IDs used at each vert.
>
> vertUVIDs = [set() for _ in range(fnMesh.numVertices)]
>
>
> Then go through the getAssignedUVs result in a loop and record which UV
> IDs are used at each vert:
> (Note: itertools.izip will be much faster than regular zip here because it
> doesn't create a new list)
> for vID, uvID in izip(polyVertices[1], polyUVIDs[1]):
> vertUVIDs[vID].add(uvID)
>
> Once you have the UV IDs at each vert, you just sum the lengths of the
> sets:
> totalVertCount = sum(len(s) for s in vertUVIDs)
>
> Note that verts with no UVs will not be counted at all this way. You might
> want to add a check that every set has at least one element in it.
>
> I can count ~20k verts in ~30ms that way, which is certainly good enough
> for games work :)
>
>
> On Friday, 10 November 2017 03:03:12 UTC+11, Benjam901 wrote:
>>
>> Hello all,
>>
>> So here is my struggle at the moment.
>>
>> I am trying to guesstimate the "actual" in-engine vert count for a given
>> object in Maya so we can validate the LOD steps per object before we export.
>>
>> *Proposed solution:*
>> The way I am trying to do this is by checking that a vertex is on a UV
>> border edge and adding this to the total vert count.
>>
>> So for example an object with 500 verts which has a UV border straight
>> through the middle will end up with 1000 verts in-engine because of the UV
>> split.
>>
>> The problem I am having is wrapping my head around the underlying data
>> models for verts, faces, edges and uvs.
>>
>> *Solution 1:*
>> I have a sort of working solution that does not use the API but instead
>> relies on the mel command: *polySelectBorderShell 1*
>>
>> import pymel.core as pm
>> import maya.mel as mel
>>
>> sel = pm.ls(sl=True)[0] # Get object selection
>>
>> # Edges must be selected here
>> mel.eval("polySelectBorderShell 1")
>> uvs = pm.polyListComponentConversion(fe=True, tuv=True)
>> uvList = pm.ls(uvs, flatten=True)
>> uvDict = {}
>> for i in uvList:
>> print i
>> uvNum = int(i.split('[')[-1].split(']')[0])
>> uvDict.update({uvNum:i})
>>
>> vertBorders = {} # e.g. {'map1':[1, 2, 3, 5, 71]}
>> uvSets = pm.polyUVSet(sel, query=True, allUVSets=True)
>> for uvSet in uvSets:
>> vertBorders.update({uvSet:[]})
>> uvs = pm.polyEvaluate(sel, uvs=uvSet, uv=True)
>> for uvNum in range(uvs):
>> if uvNum in uvDict:
>> vert = pm.polyListComponentConversion(uvDict[uvNum], fuv=True,
>> tv=True)[0]
>> vertBorders[uvSet].append(vert)
>>
>> count = 0
>> multiList = vertBorders.values()
>> result = set(multiList[0]).intersection(*multiList[:1])
>> count += len(result)
>> newMultiList = []
>> for L in multiList:
>> newList = [i for i in L if i not in result]
>> count += len(newList)
>> print count
>>
>>
>> The above solution kinda gets me there and I need to make sure its legit
>> and patch it up but for the most part it works.
>> Problem is that it is *SLOW *hence trying to use the API.
>>
>> *Solution 2:*
>> For the API I am following along with this mode of thinking here:
>> *http://forums.cgsociety.org/archive/index.php?t-729364.html
>> <http://forums.cgsociety.org/archive/index.php?t-729364.html>*
>>
>> Mu current solution and where I am stuck is here. I know I need to run
>> some comparisons but how and on what I am deadlocked at.
>>
>> def getVertFromId(dagPath, vertID):
>> vertIt = OM.MItMeshVertex(dagPath)
>> vtxIdUtil = OM.MScriptUtil()
>> vtxIdUtil.createFromInt(0)
>> vtxIdPtr = vtxIdUtil.asIntPtr()
>> vertIt.setIndex(vertID, vtxIdPtr)
>> return vertIt
>>
>> def getFaceFromId(dagPath, faceId):
>> faceIt = OM.MItMeshPolygon(dagPath)
>> faceIdUtil = OM.MScriptUtil()
>> faceIdUtil.createFromInt(0)
>> faceIdPtr = faceIdUtil.asIntPtr()
>> faceIt.setIndex(faceId, faceIdPtr)
>> return faceIt
>>
>> def getVertUVInfo(vertIn):
>> uArr = OM.MFloatArray()
>> vArr = OM.MFloatArray()
>> fIDs = OM.MIntArray()
>> uvIndices = OM.MIntArray()
>> uvSet = 'map1'
>> vertIn.getUVs(uArr, vArr, fIDs, uvSet)
>> vertIn.getUVIndices(uvIndices, uvSet)
>>
>> print uArr, vArr, fIDs, uvIndices
>> return fIDs, uvIndices
>>
>> def stripUnecessaryFaces(currentEdgeFaces, faceIDs1, faceIDs2):
>> fID1 = []
>> fID2 = []
>> for fID in faceIDs1:
>> if fID in currentEdgeFaces:
>> fID1.append(fID)
>>
>> for fID in faceIDs2:
>> if fID in currentEdgeFaces:
>> fID2.append(fID)
>>
>> return fID1, fID2
>>
>> def main():
>> mSelList = OM.MSelectionList()
>> OM.MGlobal.getActiveSelectionList(mSelList)
>> sel = OM.MItSelectionList(mSelList)
>>
>> dagPath = OM.MDagPath()
>> sel.getDagPath(dagPath)
>> dagPath.extendToShape()
>> connFaces = OM.MIntArray()
>>
>> edgeIter = OM.MItMeshEdge(dagPath)
>> while not edgeIter.isDone():
>> f1 = None
>> f2 = None
>> edgeIter.getConnectedFaces(connFaces)
>> if len(connFaces) == 1:
>> # open edge
>> print 'Open edge'
>>
>> f1 = connFaces[0] # face 1
>> try:
>> f2 = connFaces[1] # face 2
>> except:
>> pass
>>
>> vert1Index = edgeIter.index(0)
>> vert2Index = edgeIter.index(1)
>>
>> MfVert1 = getVertFromId(dagPath, vert1Index)
>> MfVert2 = getVertFromId(dagPath, vert2Index)
>>
>> fIdsvert1, uvIndicesVert1 = getVertUVInfo(MfVert1)
>> fIdsvert2, uvIndicesVert2 = getVertUVInfo(MfVert2)
>>
>> edgeIter.next()
>>
>>
>> Any suggestions on where to go from here or how to solve this is very
>> much appreciated!
>>
>> // Ben
>>
>>
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