OtakuSolutions API Reference

Overview

This video explains, before starting serious skinning (weighting) work, why BipedPlus separates the rigging layer from the skin layer.
It also covers why 3ds Max default skinning is challenging and what SkinLayer Studio offers.

Core Concept: Two Layers

The BipedPlus rig is divided into two layers with different roles.

[ Rigging Layer ]   Controllers the animator moves, constraints, etc.
       ↕
[ Skin Bone Layer ] Bones that receive mesh weights and are exported to the game engine

Remember: When assigning weights, attach them to "Skin Bones". Do not skin directly to controllers.
- The method of skinning (adding bones, entering values) is similar to standard Max workflow.
- What matters is which layer's bones you select.

3ds Max Default Skinning — Why It's Difficult

Problem	In Plain Terms
Dated workflow	UI and workflow feel cumbersome even by 2026 standards
Many bones	Hard to divide weights by zone for Twist, Corrective, etc.
Higher quality bar	More polys and bones than old mobile projects — rough work no longer passes
Envelope	Real-time zone editing — can get complex and slow

Recommendation for BipedPlus Rigs

Instead of Envelopes, entering values per vertex directly is recommended (per the video).
Rigs with many bones like BipedPlus can take extremely long if done entirely with the Max Skin Modifier alone.

What Is SkinLayer Studio

Layer-based skinning — stack weights region by region, like Photoshop layers.

Layer Example	Responsible Area
Pelvis	Pelvis only
Spine	Back · Waist
Neck	Neck
Thigh · Knee	Thigh · Knee

Each layer has a painted mask, making edits and left/right mirroring convenient.
Even with complex bones, work is divided one region at a time.
Linked to the Max viewport — check motion in real time while playing back.
Workflow speed is also relatively fast (team experience).

SkinLayer Studio is a separate tool from BipedPlus, but it is being developed by the same team and is designed to work alongside skin work.

Difference from Other Skinning Tools

Auto-skin-focused tools: may be fine for the torso, but have limits for facial or high-bone-count characters.
The approach of managing zones with layers (SkinLayer Studio, etc.) is considered more manageable by current standards.

Pre-Practice Checklist

Ep.1–4 Build · Figure · Controller complete.
Mesh to skin prepared.
Think from large regions first: pelvis → spine → legs…
Rather than using the Max Skin Modifier alone, using SkinLayer Studio or the team's designated skin tool is recommended.

Difference from Ep.6

Ep.5 (This)	Ep.6 (Next)
Why to separate, and which tool to use for skinning	BipedPlus Skin tab for weight save / load / disable

Notes

If your team already has a good skin tool, use that.
The Ep.6 Skin tab is for data management — it is a different screen from painting skin.