# Ep.17 — Customizing 02: Layer System

https://youtu.be/G5sRWu0EGRk


This document explains the BipedPlus default layers and what belongs in each one.

## 1. Hierarchy is Core, Layer is for Organization

| | Hierarchy | Layer |
|--|-----------|-------|
| Role | Parent/child, Space, constraint relationships | Node grouping, show/hide, workflow convenience |
| Importance | **Foundation** | Organization convenience |

Layer defines "where things are grouped," not "how they are connected."
Always understand structure in **Hierarchy → Layer** order.

## 2. BipedPlus Default Layer Map

| Layer (Role) | Contents | Notes |
|-------------|---------|-------|
| **Biped** | Biped bones (`Bip001…`) | Biped system only |
| **Ctrl** | Main controllers for animators | Custom Ctrl (bracelet, cape, etc.) goes here too |
| **Ctrl_Seg** | Twist / Seg detail controllers | Fine-tuning |
| **Ctrl_Seg_Pin** | Stretch / Squash Pin / Shape | Pin-style controllers |
| **Init_Ctrl** | Figure mode Init controllers | Setup phase — usually hidden during animation |
| **Modeling** | Mesh / props | Matches modeling group in Hierarchy |
| **Skin** | Skin bones | **Key** for engine export |
| **Sys** | System nodes | See Sys rules below |

## 3. Skin vs Ctrl — Role Separation

| | Skin | Ctrl |
|--|------|------|
| Purpose | Mesh deformation · Engine bones | Animator interaction |
| Role | Export reference | Animation UI |

Player users mainly interact with **Ctrl (+ Picker)** only.

### Ctrl vs Ctrl_Seg Criteria

- **Whether scale is applied**, **main controller or fine-detail element**
- Adjust to your team's preference. The key is making sure **what animators grab and what they don't** is clear.

## 4. Sys Layer Rules

A node belongs in Sys if either (or both) apply:

1. **Does not need to be in any Hierarchy — just needs to exist in scene**
2. **Animators never need to touch it**

Examples: INFO data node, Offset (Ctrl in Ctrl layer, Offset in Sys recommended), Shadow helpers

## 5. Quick Guide — Where to Place Customizations

| Addition | Hierarchy | Layer |
|----------|-----------|-------|
| Mesh (hat, pocket) | Modeling group | Modeling |
| Animator controller | Under Custom Space | **Ctrl** |
| Twist / detail | Follow module rules | Ctrl_Seg |
| Must not touch | System group | **Sys** |
| Engine bone | Skin tree | **Skin** |

## 6. One Line for Player (Animators)

Edit UI is already hidden. It is best **not to touch Init_Ctrl or Sys**.
If modification is needed, **contact your internal rigger**.