Current status: Implementing in a simple project structure first, then porting to the team engine.

Version Issues

The bone count was way too high, so I tested by switching Assimp versions:

Latest version (v143)

v140

This is from checking a single mesh. The latest version reports 67 bones, while the older version correctly shows 2.

Skinning Animation — Head and Arms Stretching Bug

Skinning animation works, but the head and arms stretch out way too long.

After debugging for a while, I found that the bones in the FBX file were sticking out above the head.

I experimented in Blender and confirmed that when vertex positions are slightly above the bones on the Y axis, the arms and hands stretch. Since my animation causes stretching, the bones must be slightly offset downward.

Model Lying Down After Blender Export

Check the Y Up option in the export settings.

If the model is still lying down, try changing Y Up to something else, export, then switch back to Y Up and export again. That fixed it.