# Ep.21 — Advanced Rigging Module · Double Knee

https://youtu.be/F3r4_59UUtI

## Overview

This video introduces **Double Knee**, a new feature in the  
**BipedPlus Advanced Rigging Module**.

In recent subculture and high-quality console games,  
demand for better **leg deformation** has grown quickly.

With a standard Biped setup, extreme knee bends often create a  
**candy-wrap** look — flesh collapsing unnaturally.  
Weight painting alone rarely fixes this; it comes from the single-hinge bone structure.

A real calf does not fold on one pivot only; it slides and opens slightly.  
**Double Knee** was added to BipedPlus to better match that behavior.

## What's covered

| Section | Content |
|---------|---------|
| Problem | Standard knee bend and candy-wrap |
| Feature | Double Knee / Push System intro |
| How to use | Check Build option → Build → setup |
| Tuning | Push · Scale · Lock workflow |
| Compare | Before / After pose comparison |

## How to use

1. In the **Build** tab, check **Double Knee** next to **Leg Link**.
2. When checked, the Extra knee-bone option is cleared automatically  
   (it is already included in Double Knee).
3. Run **Build**.
4. Continue IK and the rest of setup as usual.

## Key features

- **Push System** that updates in real time with knee bend angle
- Controllers to tune **Push Weight / contact amount**
- **Scale / Stretch·Squash** for calf and thigh when the leg folds
- **Lock** so animators do not accidentally change setup values

Default values based on the Mabel example are already filled in.  
For typical human proportions, defaults are often good enough.  
To customize: **Unlock → adjust Controllers → Lock again**.

## Notes

Knee rigging is challenging even for mid- and senior-level riggers.  
Double Knee in BipedPlus is not hard-coded to one character;  
it is a **general-purpose setup you can tune directly in Options**.

The video walks through comparisons and the full setup flow —  
please watch via the YouTube link above.

## Related

- **Ep.1** — Build tab · Preset / Biped Style
- **Ep.5–6** — Skinning prep · Skin tools
- **F.1** — Settings · Biped Plus Options

Thank you.  
**OtakuSolutions**