UBoundsFix

Fix the bounds of the Skinned Mesh Renderer.

Description

Changing the Root Bone in the Skinned Mesh Renderer doesn't affect the Bounds, but the Bounds are relative to the Root Bone. This script helps you maintain the (world) position of bounds when changing the Root Bone.

Usage

1. Put the Scripts/UBoundsFix.cs in the Scripts folder and the Editor/UboundsFixEditor.cs in the Editor folder.
2. Duplicate your GameObject to back it up.
3. Attach the UBoundsFix script to a GameObject (usually the parent of the Skinned Mesh Renderer, or select Obj manually). If everything works fine, you will see a list of Skinned Mesh Renderers in the Inspector (or you can assign them manually).
4. (Optional) Click the Detect button to detect Skinned Mesh Renderers and original root bones.
5. Assign new root bones. Note that the script won't change anything if the new root bone is the same as the original root bone.
6. Click Fix.

Why

It seems that the root bones are always the same bone from the imported model, so the bounds do not change with animations. As a result, when meshes are in the camera but bounds are not, Unity will not render them. I didn't find a way to keep the bounds while changing the root bone in the Editor, so I wrote this script.