Accessing the same color attribute multiple times return unpredictable results #117488

New Issue

Todd J. York · 2024-01-24T21:40:02+01:00

Todd J. York commented

2024-01-24 21:40:02 +01:00

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

Blender Version
Broken: 4.0.2, branch: blender-v4.0-release, commit date: 2023-12-05 07:41, hash: 9be62e85b7, type: release

Short description of error
I think bpy.types.Mesh.color_attribute is somehow bugged?

I was working on an operator for converting color attributes to vertex groups (generated by another operator from vertex groups), and had to use hacks for this to work.

Exact steps for others to reproduce the error
Run the script provided in the attached "test.blend" multiple times (undoing after each run) to see how the result is unredictable.
Changing line 5 to False will yield consistent behavior.

Other than the effects demonstrated by this file, I was experiencing the following when running the actual script (see links above) on my actual model:

crash
internal error (sorry, forgot the description, followed by a crash upon another try so now I can't investigate the console history)
random deletion of unrelated color attributes upon calling bpy.types.Mesh.color_attributes.remove()
len(attribute.data) returns the correct length, but accessing attribute.data[0] on the next line throws an "index out of range" exception

**System Information** Operating system: Windows 11 Graphics card: RTX 3060 **Blender Version** Broken: 4.0.2, branch: blender-v4.0-release, commit date: 2023-12-05 07:41, hash: 9be62e85b727, type: release **Short description of error** I think `bpy.types.Mesh.color_attribute` is somehow bugged? I was working on [an operator](https://github.com/TJYSunset/WTFB/blob/88ca5fe9e31697db287391e46a67f44ece996c99/color_attributes_to_vertex_groups.py) for converting color attributes to vertex groups (generated by [another operator](https://github.com/TJYSunset/WTFB/blob/88ca5fe9e31697db287391e46a67f44ece996c99/vertex_groups_to_color_attributes.py) from vertex groups), and [had to use hacks](https://github.com/TJYSunset/WTFB/commit/88ca5fe9e31697db287391e46a67f44ece996c99) for this to work. **Exact steps for others to reproduce the error** Run the script provided in the attached "test.blend" multiple times (undoing after each run) to see how the result is unredictable. Changing line 5 to `False` will yield consistent behavior. Other than the effects demonstrated by this file, I was experiencing the following when running the actual script (see links above) on my actual model: + crash + internal error (sorry, forgot the description, followed by a crash upon another try so now I can't investigate the console history) + random deletion of unrelated color attributes upon calling `bpy.types.Mesh.color_attributes.remove()` + `len(attribute.data)` returns the correct length, but accessing `attribute.data[0]` on the next line throws an "index out of range" exception

test.blend

949 KiB

Todd J. York added the

labels 2024-01-24 21:40:03 +01:00

Iliya Katushenock commented

2024-01-24 21:59:15 +01:00