Basic Concepts

Understanding how KawaiiPhysics works.

Architecture

KawaiiPhysics achieves bone physics using its own lightweight algorithm without using PhysX.

Animation Pose → KawaiiPhysics Node → Modified Pose
                       ↑
              Physics Simulation
              (Custom Algorithm)

Bone Chain

KawaiiPhysics applies physics to the entire bone chain starting from the Root Bone.

head (Root Bone)
├── hair_01
│   ├── hair_02
│   └── hair_03  ← Range where physics is applied
└── ponytail_01
    └── ponytail_02

Exclude Bones

You can exclude specific bones from physics calculation.

Physics Parameters

Damping

Gradually converges bone movement. Higher values stop movement faster.

Stiffness

The force that tries to return to the original animation pose. Higher values make it stiffer.

Radius

Defines the physical size of each bone. Used for collision detection.

Collision System

KawaiiPhysics supports 3 types of collision:

Type	Usage
Sphere	Spherical shapes (head, shoulders, etc.)
Capsule	Capsule shapes (arms, legs, etc.)
Plane	Flat surfaces (ground, walls, etc.)

Control with Curves

Parameters can be varied along the bone chain.

Root ←――――――――――――→ Tip
  Stiff          Soft

For more details, see Curve Editor.