A good way to store mesh components in a set ?

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Jun 17, 2021, 7:44:25 PMJun 17
to Python Programming for Autodesk Maya
Hello guys!,

What would be the fastest solution to store all the face components for each object I select into its correspondent set?

I'm trying something like this:

mesh = maya.cmds.ls(selection=True, type='mesh')[0]
selection_list = OpenMaya.MSelectionList()
dag_path = selection_list.getDagPath(0)
mfn_mesh = OpenMaya.MFnMesh(dag_path)

v_count, ids = mfn_mesh.getTriangles()

but these are only triangle counts and vtx indexes, how could I have the full face element and store in a set ?

thank you !

Marcus Ottosson

Jun 18, 2021, 3:01:43 AMJun 18
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Something like this should have you covered.

for mesh in cmds.ls(selection=True, type="mesh"):
    cmds.select("%s.f[0:]" % mesh)
    cmds.sets(name="%s_set" % mesh)

The .f[] syntax is for selecting faces, it’s what you see echoed in the Script Editor as you select a face interactively via the viewport.

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Jun 18, 2021, 7:38:53 AMJun 18
to Python Programming for Autodesk Maya
Thanks a lot Marcus, 

I was looking for an option with the API for speed, since I have scenes with more than 1k objects, do you think it's not needed in this case ?

Marcus Ottosson

Jun 18, 2021, 9:42:35 AMJun 18
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You tell me. How long does it take currently? How often do you intend on running it? How long would you like it to take?


Jun 18, 2021, 9:56:39 AMJun 18
to Python Programming for Autodesk Maya
I made a few tests on the usual number of elements, 2k / 1k, and it goes smoothly, not bad!

Thanks a lot Marcus :)

Marcus Ottosson

Jun 18, 2021, 10:12:39 AMJun 18
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Cool. :) It should be fast, you’re more or less passing the burden of actually iterating over the scene to those two commands which are already implemented in C++. So it’s likely that trying to replicate this via the Python API would be more expensive.

Juan Moraga

Jun 18, 2021, 12:54:49 PMJun 18
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I totally agree. I had a problem like this before and I ended up using a method similar to Marcus'.
As an additional note, something I found handy in the past was the "-flatten" flag of the cmds.ls() command, which will return you a list with one item for each component (faces, verts etc.).

for mesh in cmds.ls(selection=True, type="transform"):
    faces = cmds.ls(mesh + ".f[0:]", fl = True)

By the way, wouldn't the ls() in the for loop be with the type = "transform" flag instead of type = "mesh" flag?

Kind regards,

Juan Moraga
Lead Technical Director @ MondoTV

Portfolio: https://juanmoraga.carbonmade.com/
LInkedin: https://www.linkedin.com/in/juanmoragamartin/

Rudi Hammad

Jun 19, 2021, 8:26:11 AMJun 19
to Python Programming for Autodesk Maya
Not sure if that is what you are looking for, but if you want  to use the API you can do something like

mSel = OpenMaya.MSelectionList()
mDag = OpenMaya.MDagPath()
cmpMObj = OpenMaya.MObject()
mSel.getDagPath(0, mDag, cmpMObj)

faces = list()
mIt = OpenMaya.MItMeshPolygon(mDag, cmpMObj)
while not mIt.isDone():
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