# Ep.13 — Custom Mirror Factor

https://youtu.be/-VY-RPIP9nA?si=KLZLoIZOhb5No8LG

## Overview

Settings that allow **manually added controllers** (like twin tails or hair) to support **Copy · Mirror · Reset** just like Biped **arms and legs**.  
**Rigging Info registration** + **Mirror Factor** are the key.

## Prerequisites

- Complete **Space Group + Skin Bone + Ctrl + Quick Connect** as in Ep.11

## Why It's Needed — Example (Twin Tails)

- **Left Arm** mirrors correctly with Ani Utils **Copy · Mirror**.
- **Twin1 extending from the head** follows the mirror at a **strange angle** on the opposite side.

**Reason:** Left-right symmetry requires changing **"+angle → -angle" per axis**, but the rule differs **per custom bone**.  
This **per-axis ±1 rule** is the **Mirror Factor**.

A rigger can set it manually, but it's **too complex for animators** → use **Auto Calculation Mirror Factor** to compute it automatically.

---

## Step-by-Step Guide

### 1. Register **Controllers** in Rigging Info

> Register **Ctrl (controllers)**, not Skin bones — the side that animators **move**.

1. **Select all** Twin1, Twin2… (custom Ctrl).
2. **Rigging Info** → **Add**.
3. If **New Controller** etc. appears in the list, you're good.
4. **If not visible:** do **Scan → Load** then Add again.

### 2. Update

1. Click **Update**.
2. Check if **custom names** like **Twin1** appear in the **Settings** list.  
   → They may **not appear before Update**.

### 3. Auto Calculation Mirror Factor

1. Open the relevant controller's **Settings**.
2. Run **Auto Calculation Mirror Factor**.
3. **Automatic values** like "X reversed, Y·Z retained" fill in.
4. **Freely rotate/move** the **Left** Twin → **Copy · Mirror to Right**.
5. If it's **symmetrical like a mirror reflection** — **success**.

### 4. Verify Reset · Flip Also Work

| Function | Expected Result |
|------|-----------|
| **Reset All** | **Default pose** including Twin |
| **Flip Copy** | Left-right **flip** works |
| **Selection Flip Copy** | Only **selected items** flip |

→ Can be used with the **same feel as Biped bones**.

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## Rigging Info — Other Uses (Reference)

- **Reference·animation support** — pose saving, etc.
- BipedPlus **Mirror / Reset / Picker** — **mirror·default pose** data

(Details in a dedicated Rigging Info tutorial — mentioned in the video)

## Routine (Memorize This)

```
Add custom Ctrl
  → Rigging Info Add
  → Update
  → Auto Calculation Mirror Factor
  → Copy/Mirror test
```

## Notes

- Adding Ctrl without **Connect·Space Group** → Reset may work but **Mirror may feel off**.
- Only **manually adjust** Factor when Auto **doesn't match**.
- After Picker **Scan**, connect **custom buttons**.