Importing VRM causes "Basis universal cannot unpack level 1" errors

[uguu-org]

Importing VRM causes lots of "Basis universal cannot unpack level 1" error messages when using Godot 4.0.1 "Forward+" rendering mode. If rendering mode is set to "Compatibility", additional assertion errors from this line will be printed:

https://github.com/godotengine/godot/blob/0291fcd7b66bcb315a49c44de8031e5596de4216/drivers/gles3/storage/texture_storage.cpp#L1053

All error messages go away if delete this line from import_vrm.gd (from commit 86494e6) and reimport everything:

state.handle_binary_image = GLTFState.HANDLE_BINARY_EMBED_AS_BASISU

I am using Godot 4.0.1 stable, using VRM exported from VRoid studio 1.20.2 in VRM0.0 format, with material count reduced to 2 and texture size reduced to 2048. I have also tried exporting in VRM1.0 format, or export without reducing materials, which don't seem to make a difference.

I am not sure if this is a VRM issue or Godot issue, or just I did something wrong. I also found godotengine/godot-proposals#4271 that might be related.

[grilikin]

This line has other repercussions, causing #57

[fire]

This is intended to support the same vrm in both pc and mobile (like Meta quest). there is a pr for basisu. Linking in the next message.

[fire]

I have to go for GDC opening today, so will review as soon as possible.

[fire]

This issue doesn't happen later Godot Engine releases.

[lyuma]

For now I have changed godot-VRM to use embed as uncompressed which is going to take a lot of VRAM. There are some pretty serious bugs in the glTF import of Basis Universal textures, due to a mismatch between images and textures arrays. We will have to patch that first, and then see if that solves some of the issues here.