USDA import crashes Blender during material assignment to geometry subsets #125184

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Geoff Gerber · 2024-07-21T18:55:29+02:00

Geoff Gerber commented

2024-07-21 18:55:29 +02:00

System Information
Operating system: Windows 11
Graphics card: NVidia 3060

Blender Version
Broken: 4.1, 4.3 alpha (through debugger as well)
Worked: unknown

When importing some .usda files, Blender crashes

Exact steps for others to reproduce the error

Using the USD Import function, import the provided .usda file.
Blender crashes to desktop. When run through the debugger, it's failing on line 766 of the usd_reader_mesh.cc file.

I've run the file through usdchecker and it seems valid. I can inspect it in usdview as well.

Note: You may have to import it more than once. This bug does seem intermittent, and I'm not sure what would cause that. The material bindings seem to all properly reference the proper material prim.

**System Information** Operating system: Windows 11 Graphics card: NVidia 3060 **Blender Version** Broken: 4.1, 4.3 alpha (through debugger as well) Worked: unknown **When importing some .usda files, Blender crashes** **Exact steps for others to reproduce the error** - Using the USD Import function, import the provided .usda file. - Blender crashes to desktop. When run through the debugger, it's failing on line 766 of the usd_reader_mesh.cc file. I've run the file through usdchecker and it seems valid. I can inspect it in usdview as well. Note: You may have to import it more than once. This bug does seem intermittent, and I'm not sure what would cause that. The material bindings seem to all properly reference the proper material prim.

adder_a_cockpit_standard.usda

3.9 MiB

Geoff Gerber added the

labels 2024-07-21 18:55:29 +02:00

Jesse Yurkovich commented

2024-07-21 21:21:49 +02:00

I'll confirm the crash - the issue is that the USD file is setting per-point materials whereas we only support per-face; so we're using the wrong indices to assign the materials and corrupting memory.

That said the story is a bit more complicated:

This USD file uses "vertex" for the elementType of the geometry subset. This is incorrect. USD says that only the following tokens are permitted: "[face, point, edge, tetrahedron]". This needs to be reported to whatever software created this file (CgfConverter) and rectified as soon as possible so broken files don't proliferate further. @Geoffrey-Gerber can you do this?
The usage of per-point subsets was only added in USD 24.03 earlier this year, so not much software can use it (my version of Houdini doesn't and still only says that face is supported). It is strange that CgfConverter is choosing to do this at all when dealing with materials; I wonder why.

CC @makowalski for awareness

I'll confirm the crash - the issue is that the USD file is setting per-point materials whereas we only support per-face; so we're using the wrong indices to assign the materials and corrupting memory. That said the story is a bit more complicated: - This USD file uses "vertex" for the `elementType` of the geometry subset. This is incorrect. USD says that only the following tokens are permitted: "[face, point, edge, tetrahedron]". This needs to be reported to whatever software created this file (`CgfConverter`) and rectified as soon as possible so broken files don't proliferate further. @Geoffrey-Gerber can you do this? - The usage of per-point subsets was only added in USD 24.03 earlier this year, so not much software can use it (my version of Houdini doesn't and still only says that face is supported). It is strange that `CgfConverter` is choosing to do this at all when dealing with materials; I wonder why. CC @makowalski for awareness

Jesse Yurkovich added

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USDA import crashes Blender during material assignment to geometry subsets #125184