Skeleton unit scaling is awkward

[bqqbarbhg]

Issue description

Importing small meshes exported from Maya with 1cm units causes the model to be loaded correctly as tiny, but the bounding box is massive as the Skeleton3D itself it not scaled, but only the root node within.

Could try to scale the Skeleton3D node itself, but then we need to be careful to compensate for that in animations etc. alternatively we could bake the scaling into the root node, but that had some issues as well and will require us to have an unnecessary node.

Steps to reproduce

• Import ufbx/data/maya_game_sausage_7500_ascii_combined.fbx
• Observe that the bounding box is 100x larger than it should be

Minimal reproduction project (For SDK or engine issues)

No response

Using a released version?

0b874ae

What OS? Any other relevant information? (godot-ufbx revision, Godot revision, System information)

Windows, Godot 4.2 master

[bqqbarbhg]

Turns out that there's not much that can be done here as the bounding box size is based on the mesh, so even if we'd fix the scale issue on bones the bounding box may be rotated. I saw that the glTF importer transforms the mesh geometry itself but that's not ideal especially for blender files, as then you end up with nodes having scale=100 and all vertices being scaled to tiny.

[fire]

The transform to identity scale to the mesh geometry itself is part of the scene importer and independent of the importers.

Also agree that this is really a rendering of Godot Engine issue and it's minor as this is used for culling (bug?) and editor debug.

[fire]

I'd probably close the issue as I have no approaches for fixing this.

[bqqbarbhg]

Yeah every approach has it's downsides, I'd consider this a Godot Engine issue as well.

[fire]

see godotengine/godot#84451 @bqqbarbhg

[bqqbarbhg]

Yeah would need something similar for 3D probably, one solution is to just calculate maximum distance from bone to vertex and estimate the skeleton AABB by approximating bone sizes as such. Adding some fudge factor it works in practice.