Import of certain meshes produces error with Maya vertex color importer

[Polymega]

With the .maps I've tested so far, they've been importing into Maya by-and-large without issue (including retaining vertex color information). However, for ap34.map, I receive the following warning in Maya and the geometry imports as a single mesh with no vertex color information intact:

# Error: RuntimeError: file C:/Users/John/Documents/maya/2022/scripts\ObjVColorMaya.py line 216: Can't read vColor! # 

Through some additional tests, this is only happening when I import the Opaque Mesh master group from the tool. If I import any of the Transparent or Decal master groups then it imports correctly, with vertex color information and separate groupings intact.

I'm not sure what's causing the import error for this particular map, but it might very well be an issue with other maps I haven't come across yet.

For that RuntimeError mentioned above, here is the portion of code relating to it:

    def vColorApply(self, objName, vColor):
        mSel = om2.MSelectionList()
        mSel.add(objName)

        mDag = mSel.getDagPath(0)
        mfnMesh = om2.MFnMesh(mDag)
        vtxCount = mfnMesh.numVertices

        if len(vColor) == vtxCount:
            mfnMesh.setVertexColors(vColor, range(vtxCount))
        else:
            mc.error("Can't read vColor!")
            return
        mc.polyOptions(mDag, cs=1)

And attached is the Python script in its entirety.
ObjVColorMaya.zip

[Polymega]

Please let me know again if you prefer individual tickets like what I sent the other day, or prefer to have a list in one ticket.

Out of what I sent the other day, this would be the high priority for me as I'm unable to work on certain .map files in the meantime.

[pmttavara]

Sorry, this will take me a bit longer, since I think I will need to get a copy of the version of Maya you're using to replicate this.

Individual tickets are working well for me! 👍

[Polymega]

The same issue is happening with ma85. Like with ap34, the error only happens with the Opaque Mesh Group. Maya will import with vertex colors and separate grouping for the Transparent and Decal Groups without issue.

[Polymega]

List of affected maps found so far:

• cc13
• ap06
• rr29
• ap34
• ma85
• hp01

[Polymega]

Added a few more maps affected by this error, in case it helps to compare to see what similarities (if any) these maps share to cause this to happen.

Note again this seems to only affect the Opaque Group upon import into Maya with the vertex color importer script.

[Polymega]

Wanted to give an update on this issue to hopefully put you at ease some.

I was able to work around this issue for my current needs. The solution I found is "hacky", but ultimately everything seems to have turned out fine.

I was able to make things work by exporting the geometry out of the tool, re-import that OBJ back into the tool, then re-export it once again. By doing this process, Maya was then able to correctly import the OBJ file with vertex color intact.

In other words, it seems like when your tool re-imported the OBJ it made, something got "fixed" for the re-export. So when the time comes, I recommend doing this and noting any differences between the first- and second-export of the OBJ to see what's different in the data. Hopefully that may shed a clue on what the problem is in the first place.

---

........ the one exception to this "fix" was rr29. Following the "fix" mentioned above, this one still didn't import vertex colors into Maya. This one was... weird. Here's what I tried:

1. I tried the steps mentioned above.
2. I imported into Blender. While Blender imported it with vertex color information, the vertex colors were "corrupted", for a lack of better term.
3. I used an online OBJ viewer. This one, to be precise. The OBJ imported with the vertex colors correct/intact, but it didn't have an option to export in any format while preserving vertex color information and/our mesh grouping.
4. I then found and used MeshLabs. When imported into there, the vertex colors were also correct/intact and it has several export options with the ability to keep vertex colors. However, when exported as OBJ through this tool, it preserves the vertex colors but merges everything into one mesh.

Here is the ultimate solution that worked. Get ready... It's weird...

1. Import the OBJ into here (it's a different online 3D viewer): https://fetchcfd.com/3d-viewer
2. "Download" (NOT "Export") the OBJ back out.
3. Import this OBJ into the tool.
4. Export as OBJ from the tool.
5. Import this OBJ into the tool.
6. Export as OBJ from the tool.
7. It will now import into Maya while preserving separate groups and retaining vertex color information.

I'm not sure why rr29 was so much more troublesome...

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EDIT: Fixed a lot of typos and errors in my post. Been a long Monday... 😅