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Tips

日本語版

Useful features and techniques for KawaiiPhysics.

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Dummy Bone

A feature to improve physics control of end bones.

When to Use

• Short bone chains like bangs or earrings
• When end bone movement looks unnatural
• When you want to animate with just one bone

Setup

1. Set Dummy Bone Length to a value greater than 0
2. Adjust based on bone length (start with around 5-10)

Key Points

• Setting Dummy Bone Length adds a virtual bone at the end
• This allows the end bone to be affected by physics simulation

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Curve Data

A feature to vary parameters based on bone position (root to tip).

When to Use

• Want the root to be stiff and the tip to be soft
• Want more movement at the tip
• Want to change collision radius based on position

Recommended Curves

Curve	Effect
Stiffness Curve	Make tips softer
Damping Curve	Increase tip movement
Radius Curve	Reduce tip collision

Example: Softer Tips

Stiffness Curve Data:

• X=0.0 (root): Y=1.0
• X=1.0 (tip): Y=0.3

This multiplies the Stiffness parameter by 0.3-1.0.

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Bone Constraint

A feature to maintain distance between adjacent bone chains. Uses XPBD (Extended Position-Based Dynamics).

When to Use

• Skirt bone chains separate too much
• Cape spreads too wide
• Want to link multiple chains

Setup

1. Add bone pairs in Bone Constraints section
2. Set adjacent bones as pairs
3. Adjust stiffness with Global Compliance Type

Share with DataAsset

Using Bone Constraints Data Asset allows sharing settings across multiple AnimBPs. Also supports regex-based bone specification.

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Sync Bone

Added in v1.20

A feature to synchronize target bones with reference bone movement.

When to Use

• Solve skirt penetrating legs
• Solve cape penetrating body
• Want penetration countermeasures without ControlRig or PoseDriver

Comparison with Traditional Methods

Method	Features
ControlRig	Powerful but complex setup
PoseDriver	Pose-based and flexible but requires separate setup
Sync Bone	Self-contained in KawaiiPhysics node, simple

Setup

1. Open Sync Bones section
2. Source Bone: Set reference bone (e.g., leg bone)
3. Target Bones: Set affected bones (e.g., skirt bones)
4. Adjust movement with parameters

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External Forces

A feature to apply external force presets.

Preset Types

Preset	Usage
Basic	Apply constant directional force
Gravity	Link to character's gravity settings
Curve	Force that changes over time

Wind Effects

1. Enable Enable Wind
2. Place WindDirectionalSource in level
3. Adjust influence with Wind Scale
4. Add randomness with Wind Direction Noise (v1.19)

Bone Filters

Use Apply Bone Filter / Ignore Bone Filter to limit which bones receive external forces.

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Related Links

• Quick Start - Basic setup
• Parameter Reference - All parameter details
• Tutorials - Setup guides by use case
• FAQ - Frequently asked questions