Exported Model Issues - Head Parenting, Scale Inconsistency, Missing T-Pose

[LandonAndEmma]

Issue: Exported Model Issues - Head Parenting, Scale Inconsistency, Missing T-Pose

Description

The current Mii animation export tool introduces workflow hurdles due to three key issues requiring manual fixes in Blender:

---

1. Head Parenting & Alignment

• Problem:
  The head exports as a separate object (not parented to the body rig), causing misalignment after manual parenting.
• Current Workaround:
  • Manually parent the head to the body rig.
  • Add a head vertex group to the head mesh.
  • Apply the Deform > Armature modifier.
  • Manually adjust the head's vertical position (no guidance on correct offset).
• Impact: Extra steps and guesswork to align the head with the body.

---

2. Scale Inconsistency

• Problem:
  The rig/model scale varies based on Mii Maker body size parameters, forcing users to reset scales manually.
• Impact: Users must apply scale corrections (resetting to 1) to ensure consistent sizing.

---

3. Missing T-Pose Export

• Problem:
  No default T-pose is provided, complicating animation setup.
• Current Workaround:
  Manually set each bone’s primary rotation axis to 1 and others to 0.
• Request: Add an export option to generate a T-pose automatically.

---

Expected Behavior

1. Automatic Head Parenting:
   • Head should be pre-parented to the body rig with correct offsets.
2. Consistent Scale:
   • Model/rig scale should remain uniform regardless of Mii body size settings.
3. T-Pose Export Option:
   • Include a checkbox/toggle to export the rig in a T-pose.

---

Environment

• Software: Blender (tested on latest versions during import).

Impact

These fixes would drastically reduce manual post-processing and improve user workflow efficiency.

[ariankordi]

Can you give the input you gave to ChatGPT to write this issue?

I'll go through these in a bit more detail...

Head Bone Parenting

This seems obvious on the surface. If I look into the glTF, MiiHead is a distinct object that is not a part of the body at all, just that the matrix is set to the head bone's position.

You'd expect that head would be its own node alongside body_f, hands_f, legs_f and attached to head but it's not.

This may actually be because "head" is both a bone that represents the neck, and the head is supposed to be attached to it. So if you scale the entire body, the "head" bone, or the neck, will be scaled along with it, and that IS what SHOULD happen but the Mii head itself should receive no scaling, just rotation and translation.

Actually, there's this line specifically mentioning that the head is not attached to the head bone, and if you scale the body you can see this...

mii-creator/src/class/3DScene.ts

Line 931 in 1b4b48c

// head is no longer attached to head bone physically, no more need to offset rotation

This issue is related to the lack of proper Mii body scaling, whereas different bones get different scales (for example, the hand spheres are NOT supposed to receive stretching in any direction, and the arms are farther apart from the body). This is something both me and kat had banged our heads at collectively and I only kinda sorta figured it out, and dealt with this myself, though my solution won't be applicable to Three.js or glTF.

Something that may work though is if you just skip scaling on the head bone on the body, so, this means the neck. Because what it's supposed to look like if you scale it properly, is like this:

If you don't scale the head bone at ALL, you get this, which, is actually perfectly fine since you never see the neck in normal circumstances.

Maybe kat can make a special case to scale this bone specifically and it shouldn't deform the rest of the body, I don't know. But I think that's why it is the way it is now.

Body Scaling?

The rig/model scale varies based on Mii Maker body size parameters, forcing users to reset scales manually.

Are you asking that body scale should not be applied at all? Which, by body scale, we of course mean the stretch on the entire mesh rather than the per-bone morph scaling... stuff that isn't yet implemented in Three.js.

I can see why you'd want an option to disable this, and it probably wouldn't hurt to add.
But since the scale does appear in Blender and you can change it back to 1, 1, 1... I'm afraid I don't see the problem. It would be a problem if it were stretched and the scale did in fact wrongly show as (1, 1, 1) but it doesn't.
You should elaborate what you meant by this.

"T-Pose Export"

Or to be more precise, the bind pose.
Yeah, I did just see now that the pose is baked into the model without skinning. If you remove the armature you still see the pose. I still don't know if just giving you a T-posed model would help since you need to bind the armature (or something I don't know Blender), but if the pose weren't baked in and were applied using glTF skinning then you'd at least be able to remove it in Blender.

Summary

• The head is not parented to the body probably because of issues with body scaling affecting the head which need to be addressed.
• The export should not bake the pose, it should be applied using glTF skinning.
• Need more clarification on their issue with body scaling.

[LandonAndEmma]

Yes I did use ChatGPT to make my issue better cause if it wasn’t I wasn’t sure you would understand me.
I guess the 2nd issue wasn’t that descriptive but when I apply all transforms in blender to my Mii’s model it seems to ruin the entire thing, sure it’s a stupid issue, but I’d rather it be scaled normal size and the vertices be where the are in space, I’m asking cause for game modding to mod your Mii in places it’s a necessity to apply all transforms, I’ll try to provide a video of what happens when I do this. So yeah the body scaling needs to be applied as a transform when exported, cause for some reason it’s having issues in blender when I do it myself after export.

[LandonAndEmma]

Gonna have to wait till #62 is resolved so I can show you what I mean.

[LandonAndEmma]

Wait it’s fixed the website is just still down.

[ariankordi]

You can attempt to run the new branch where that’s implemented but no guarantees that it’ll work or that it’s easy to set up: https://github.com/datkat21/mii-creator/tree/renderer-ffl.js-prototype

[LandonAndEmma]

Guess I’ll wait till it’s fully done, I’m not gonna close this issue since it hasn’t been fixed I will not message here till it’s finished on website cause I don’t want to clog development.