[Improvement] Avatar Creation Improvement (not a configure tool but a feedback to the user so they can know the bones are assigned correctly)

[XtroTheArctic]

Describe the bug 💬

IMPORTANT: This is not a bug perse. I tried to change the new issue type but GitHub doesn't provide other types of issues.

Since I switched from using FBX to using GLTF in my project few weeks ago, I became a lover and a supporter of GLTF format and UnityGLTF package. I tried other available Unity GLTF packages including the official one but, to say it kindly... UnityGLTF is superior in every aspect. I have been noticing some of its limitations or small bugs too. While using awesome features of UnityGLTF, I also would like to spend my limited time on fixing some of its problems. That's why I submitted my first PR few days ago.

After converting my static models to GLTF, I started converting my character models and I noticed that avatar creation part of UnityGLTF is one of its limitations. For example, unlike Unity's FBX importer, UnityGLTF doesn't have a Avatar Configuration tool. As I saw in another ticket, it's considered out of scope for this project. I agree with that considering the man power available on this project but still, assigning the avatar bones correctly is very very important for proper GLTF usage for character animation purposes. For this reason, I believe that UnityGLTF must at least offer a feedback mechanism to the user so they would know if all the bones were assigned to child gameobjects in their model.

While checking and commenting on another related ticket (#794) I decided that I could work on such a feedback mechanism implementation and submit it as my second PR if it make sense to the owners of this project. That's why I created ticket so I can continue my research and implementation without disrupting other topics in other tickets.

The plan I have in my mind for this avatar creation feedback mechanism is to show a list of Mecanim bones and the list of gameobjects which are assigned to those bones similar to Unity's avatar configuration tool but without the editing/modification options.

In the comments section below, I'll keep this ticket updated with my findings and results before submitting a PR.

Thanks for your understanding in advance.

Steps to reproduce 🔢

1. Import a GLTF model into Unity.
2. See that there is no way to know if the bones were assigned correctly.

Files to reproduce the issue ♻

No response

Editor Version 🎲

Other (Provide details below)

Render Pipeline and version

Not related to URP

UnityGLTF Version

2.16.1

Operating System 👩‍💻

Other (Provide details below)

When does this problem happen?

• Editor Import
• Runtime Import
• Editor Export
• Runtime Export

Additional Info 📜

No response

Validations 🩹

• I have searched existing issues: no issue already exist that reports the same problem.
• I follow the Code of Conduct
• I provided a minimal reproducible example, including files when necessary.

[XtroTheArctic]

My first research findings go like this:

Unity's FBX importer expects to see all the skeleton child gameobjects in these exact names. It may recognize other naming formats but these are the bare minimums I can reproduce and these names are very similar to mecanim bones names.

Unity makes the bone name validation correctly only when the model is imported into the project for the first time. Changing the bone names via Blender (or others) isn't sufficient when re-importing and existing model in Unity because it keeps the prior bone assignments and it tries to find the old names. The best way to test fresh bone name validation is to delete the .fbx.meta file.

Optional bone names are marked with parentheses below.

Hips > Spine > (Chest) > (UpperChest) > (Neck) > Head > (Jaw)
___________________________________________________________ > (LeftEye)
___________________________________________________________ > (RightEye)
________________________________ > (LeftShoulder) > LeftArm > LeftForearm > LeftHand > (LeftThumb1 > LeftThumb2 > LeftThumb3)
__________________________________________________________________________________________ > (LeftIndex1 > LeftIndex2 > LeftIndex3)
__________________________________________________________________________________________ > [Repeat for other fingers: Middle, Ring, Pinky]
________________________________ > (RightShoulder) > RightArm > RightForearm > RightHand
_____ > LeftUpLeg > LeftLeg > LeftFoot > (LeftToe)
_____ > RightUpLeg > RightLeg > RightFoot > (RightToe)

[XtroTheArctic]

The model I'm using for testing avatar creation contains 52 bones in Blender and all of them are assigned to child gameobjects by the FBX importer as seen in avatar's inspector debug mode.

The same model contains only 19 bones assigned correctly by UnityGLTF's latest version (2.16.1).

UnityGLTF should be able to recognize and assign these 52 bare minimum (simplistic/similar to avatar bones) names at least and it should show the user a status of bone assignments without needing to use the inspector's debug mode.

[XtroTheArctic]

I submitted a PR for this.