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pafuhana1213 edited this page Jan 11, 2026 · 3 revisions

Parameter Reference

日本語版

Explanation of all KawaiiPhysics parameters.


Table of Contents


Modify Target

Configure which bones to control.

Root Bone

Control the specified bone and all bones below it.

v1.17+: Multiple Root Bones can now be configured.

Exclude Bones

Exclude the specified bone and all bones below it from control.

Dummy Bone Length

If greater than 0, adds a dummy bone to the end of the control bones. Adding a dummy bone improves physics control of the end bone.

Bone Forward Axis

Specifies the forward direction of the bone. Affects physics control and dummy bone placement.


Physics Settings

Basic parameters for physics simulation.

Damping

Damping of physical behavior. As the value is smaller, acceleration is more reflected in the physical behavior.

  • Reference: 0.1-0.3

Stiffness

Stiffness of physical behavior. As the value is larger, pre-physics shape is more respected.

  • Reference: 0.05-0.2

World Damping Location

Influence from movement in world coordinate system of Skeletal Mesh Component.

  • Reference: 0.5-0.8

World Damping Rotation

Influence from rotation in world coordinate system of Skeletal Mesh Component.

  • Reference: 0.5-0.8

Collision Radius

Radius of each bone's collision.

Limit Angle

Rotational limitations in physical behavior. Setting the value properly can prevent erratic behavior.

Target Frame Rate

Target frame rate for physics simulation.

Warm Up Frames

Number of physics warm-up iterations. Used when you want to start/display after physics processing has settled down.

Teleport Distance Threshold

If the movement amount of a SkeletalMeshComponent in one frame exceeds the set value, that movement will not be reflected in physics control. Used to prevent erratic behavior during teleportation.

Teleport Rotation Threshold

If the rotation amount of SkeletalMeshComponent in one frame exceeds the set value, that rotation will not be reflected in physics control.

Planar Constraint

Fix bones on the specified plane axis.

Update Physics Settings In Game

Flag to update physics parameters of each bone every frame. Disabling this will slightly improve performance, but physics parameters cannot be changed during execution.

Reset Bone Transform When Bone Not Found

Flag to reset Transform when the controlled bone is not found. Generally should be disabled.

Skeletal Component Movement Scale

Added in v1.19

Adjusts the influence of SkeletalMeshComponent movement on physics simulation. Useful for adjusting behavior on elevators and moving platforms.


Simulation Space

Added in v1.19

Configure the coordinate system for physics simulation.

Simulation Space

Select the coordinate system for simulation.

Value Description
Component Space Component coordinate system (traditional behavior)
World Space World coordinate system
Base Bone Space Base bone coordinate system

Use Case:

  • When the root bone rotates 180 degrees within a single frame, using World Space or Base Bone Space provides more stable results.

Curve Data

Curve data to vary parameters based on bone position.

Formula:

Length from RootBone to specific bone / Length from RootBone to end bone

The curve value at this position (0.0-1.0) is multiplied with each parameter.

Damping Curve Data

Corrects the Damping parameter.

Stiffness Curve Data

Corrects the Stiffness parameter.

World Damping Location Curve Data

Corrects the World Damping Location parameter.

World Damping Rotation Curve Data

Corrects the World Damping Rotation parameter.

Radius Curve Data

Corrects the Collision Radius parameter.

Limit Angle Curve Data

Corrects the Limit Angle parameter.


Limits

Collision settings.

Spherical Limits

Spherical collision.

Capsule Limits

Capsule collision.

Planar Limits

Planar collision.

Box Limits

Debug visualization added in v1.20

Box collision.

Limits Data Asset

Collision settings (DataAsset version). Recommended when you want to reuse settings across AnimNodes or ABPs.

v1.16+: Bone selection improved from text input to hierarchy menu. Export button for Limits added.

Collision Auto Generation

Added in v1.17

Feature to automatically generate collision shapes.


Bone Constraint

Added in v1.14, promoted to Production Ready in v1.19

Uses XPBD (Extended Position-Based Dynamics) to maintain distance between bones. Useful for preventing adjacent bone chains (such as in skirts) from separating too much.

Global Compliance Type

Stiffness type used in Bone Constraint.

Constraint Iteration Count (Before Collision)

Number of Bone Constraint iterations before collision processing.

Constraint Iteration Count (After Collision)

Number of Bone Constraint iterations after collision processing.

Auto Add Child Dummy Bone Constraint

Flag to automatically process dummy bones when end bones are subject to BoneConstraint processing.

Bone Constraints

Sets bone pairs to be processed by BoneConstraint. Used when you want to maintain distance between bones, such as skirts.

Bone Constraints Data Asset

BoneConstraint settings (DataAsset version). Recommended when reusing settings across AnimNodes or ABPs. Also supports regex-based bone configuration.


Sync Bone

Added in v1.20

Feature to apply reference bone displacement to target bones. Useful for solving problems like skirt leg penetration.

Overview

Sync Bone synchronizes target bones (e.g., skirt bones) with the movement of specified reference bones (e.g., leg bones). This allows you to reduce penetration issues without separately configuring ControlRig or PoseDriver.

Use Cases

  • Solving skirt penetrating legs
  • Solving capes penetrating body

External Force

External force settings.

Gravity

External forces (gravity, etc.).

Use Legacy Gravity

Added in v1.20

Flag to use legacy gravity processing. Enable this if you want to maintain previous behavior after v1.20's improved gravity processing.

Use Gravity Direction in World Space

Added in v1.20

Flag to use gravity direction in world space.

Use Default Gravity Z Project Setting

Added in v1.20

Flag to multiply the DefaultGravityZ value from project settings with gravity.

Simple External Force

Simple external force vector. Use when you want to apply a constant force separately from gravity.

Use World Space Simple External Force

Flag to process Simple External Force in world coordinate system.

Enable Wind

Enable wind influence from WindDirectionalSource. Intended for use with Cloth and SpeedTree.

Wind Scale

Wind influence from WindDirectionalSource.

Wind Direction Noise

Added in v1.19

Adds noise to wind direction. Prevents unnatural appearance when camera direction matches wind direction.

External Forces

External force presets. You can add custom presets in C++ (Instanced Struct).

Custom External Forces

Warning: VERY EXPERIMENTAL feature

You can add custom presets in BP or C++ (Instanced Property).

Important: Will not work properly unless you click on AnimNode or compile ABP.


World Collision

Collision detection settings for level geometry.

Allow World Collision

Flag for collision detection with level collisions.

Warning: Enabling this will significantly increase physics processing load.

Override Collision Params

Use custom collision settings in WorldCollision instead of SkeletalMeshComponent's collision settings.

Ignore Self Component

Flag to ignore SkeletalMeshComponent's collision (PhysicsAsset) in WorldCollision.

Ignore Bones

Ignore collision for specified bones in WorldCollision.

Ignore Bone Name Prefix

Ignore collision for bones with specified prefix in WorldCollision.


External Force Presets

Common settings and type-specific settings for external force presets.

Common Settings

Apply Bone Filter

Specify bones to apply external force. Force will not be applied to unspecified bones.

Ignore Bone Filter

Specify bones to NOT apply external force.

External Force Space

Specify the space for external force.

Random Force Scale

Specify the range of random force scale.

Basic

Basic external force preset.

  • Force Dir: Direction of external force
  • Force Rate By Bone Length Rate: Corrects Force Rate applied to each bone
  • Interval: Interval for applying force

Gravity

Gravity preset.

  • Force Rate By Bone Length Rate: Corrects Force Rate applied to each bone
  • Use Character Gravity Direction: Use CustomGravityDirection set on Character
  • Use Character Gravity Scale: Use GravityScale set on Character

Curve

Curve-based external force preset.

  • Force Curve: Set external force that changes over time using a curve
  • Curve Evaluate Type: Curve evaluation method
  • Substep Count: Number of time divisions
  • Time Scale: Scale of time
  • Force Rate By Bone Length Rate: Corrects Force Rate applied to each bone

AnimNotify

Features for integration with animations.

AnimNotifyState: Set Alpha

Added in v1.20

Override the Alpha value of KawaiiPhysics node during specific animation segments. Use when you want to temporarily disable physics effects.

Use Cases:

  • Disable physics during specific animations
  • Reduce physics effects during cutscenes

Gameplay Tag

KawaiiPhysics Tag

Tag for identifying/filtering KawaiiPhysics nodes from AnimNotify or external systems. Useful when you need to target specific nodes when using multiple KawaiiPhysics nodes.


Debug & Console Variables

Added in v1.16

Console Variables

Variable Description
a.AnimNode.KawaiiPhysics.Enable Enable/disable KawaiiPhysics
a.AnimNode.KawaiiPhysics.Debug Enable/disable debug display
a.AnimNode.KawaiiPhysics.Debug.LengthRate Debug display for length ratio

Debug Visualization

Extended in v1.20

  • Added visualization for Box and Plane collisions
  • Line thickness can be adjusted via console variables

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