Changelog

Changelog for KawaiiPhysics.

For the latest release information, see GitHub Releases.

v1.21.x (UE 5.3 - 5.7 Support)

v1.21.0

Fixed Substepping (Frame-rate Independence)

Added a feature that runs the whole simulation with fixed-timestep substepping (FixedDt = 1 / TargetFramerate) for stable, frame-rate-independent physics. It is enabled (ON) by default.

• Controlled via Use Fixed Substepping / Max Substeps under Project Settings > Plugins > Kawaii Physics
• [Behavior change] Because it defaults to ON, the way bones sway may change slightly compared to previous versions. Turn it OFF if you need the legacy behavior.

See Fixed Substepping for details.

Bone Subdivision

Added a feature that inserts virtual dummies between real bones — without modifying the real skeleton — to raise collision resolution.

• BoneSubdivisionCount / bBoneSubdivisionCollisionOnly / bBoneSubdivisionDensifyByRadius (densify by radius)
• Horizontal BoneConstraint Subdivision (bridge dummies): BoneConstraintSubdivisionCount / BoneConstraintSubdivisionFeedbackScale prevent penetration between columns
• Combined with BoneSubdivisionCount, collision points form a 2D grid across the cloth surface

See Bone Subdivision for details.

Shared Collision

Added a feature that lets multiple KawaiiPhysics nodes (including separate SkeletalMeshComponents and ChildActors) share a single set of collision shapes.

• Source / Target roles grouped by SharedCollisionGroupTag
• Shared within the same Actor/ChildActor family
• Source/Target/tag can be switched at runtime via the Blueprint API

See Shared Collision for details.

Sync Bone Enhancements

• Per-axis apply direction (ApplyDirectionX/Y/Z: Both/Positive/Negative/None)
• Distance attenuation (bEnableDistanceAttenuation, etc.)
• Automatic child expansion (bIncludeChildBones) and scale curves by length rate / movement distance

Other Improvements

• Added WindDirectionNoiseAngle (wind direction noise) to Wind
• Added the project-wide KawaiiPhysicsDeveloperSettings (fixed substepping / dummy-generation warning thresholds)
• Added an automated physics-core test suite (UE Automation) to strengthen regression detection
• Various build error fixes and performance optimizations (supported engine versions: UE 5.3-5.7)

For the latest release information, see GitHub Releases.

v1.20.x (UE 5.7 Support)

v1.20.0

Sync Bone Feature

Added a feature that applies the movement and rotation of a specified bone to physics-controlled bones. Effective for preventing skirt penetration through legs.

Preventing penetration with SyncBone and Collision combined

Full demo combining SyncBone, BoneConstraint, and Collision

• Reflects source bone position/rotation to physics bones
• Prevents penetration without using collisions
• Lightweight processing with excellent performance

Gravity System Improvements

• Added Gravity Direction parameter
• More flexible gravity control available

AnimNotifyState: Set Alpha

Added AnimNotifyState that can dynamically change physics blend ratio during animation.

• Control physics influence on animation timeline
• Smooth blend in/out

Debug Feature Enhancements

• Added Box Limit debug display
• Improved Planar Limit debug display
• Debug filtering with GameplayTag

See GitHub Discussion #165 for details.

v1.19.x (UE 5.6 Support)

v1.19.0

Simulation Space Feature

You can now select the coordinate space for physics simulation.

ComponentSpace vs WorldSpace comparison

Value	Description
ComponentSpace	Component space (default)
WorldSpace	World space
BaseBoneSpace	Specified bone space

Using WorldSpace or BaseBoneSpace can avoid the effects of sudden Root bone movement/rotation.

WorldSpace behavior

Sample Project Refresh

• Updated all samples to latest best practices
• Added demos for new features

BoneConstraint Feature Stabilization

The BoneConstraint feature introduced experimentally in v1.14.0 is now official.

Fab Distribution Started

Distribution started on the Fab store.

• Fab

See GitHub Discussion #155 for details.

v1.18.x (UE 5.5 Support)

v1.18.0

Copyright Notice Added

• Added MIT license copyright notices to all source files

Packaging Error Fix

• Fixed packaging failures in some environments

Other Improvements

• Official UE 5.5 support
• Minor bug fixes

See GitHub Discussion #145 for details.

v1.17.x (UE 5.3-5.5 Support)

v1.17.0

Multiple RootBone Support

You can now set multiple RootBones in a single AnimNode.

• Specify additional RootBones with AdditionalRootBones parameter
• Individual ExcludeBones list available for each RootBone
• Control multiple bone chains with the same parameters

Box Collision

Added box-shaped collision.

• Optimal for rectangular shapes like body and buildings
• Offset and rotation adjustable

PhysicsAsset Integration

You can now auto-generate collision shapes from existing PhysicsAssets.

• Just specify the PhysicsAsset for automatic conversion
• Reduces manual collision setup work

AnimNotify Support

You can now control physics parameters from animation notifies.

• AnimNotify_KawaiiPhysics_ResetDynamics
• AnimNotify_KawaiiPhysics_SetExternalForce

GameplayTag Support

Debug targets can be filtered using GameplayTags.

Wind Directional Source Support

Now supports Unreal Engine's Wind Directional Source.

• Automatically affected by wind placed in level
• Adjust influence with WindScale

See GitHub Discussion #138 for details.

v1.16.x (UE 5.3-5.5 Support)

v1.16.0

New External Force System

Significant improvements to the process of applying external forces. Multiple external force presets have been added that allow you to apply force at regular intervals only to certain bones in the bone's local coordinate system.

• Multiple presets can be combined
• Custom presets can be implemented in C++

Details Panel Reorganization

• Property names and categories reorganized
• Debug features converted to buttons
• Tooltips added for all properties

Console Variables for Debugging

New console variables added for level debugging:

• a.AnimNode.KawaiiPhysics.Enable
• a.AnimNode.KawaiiPhysics.Debug
• a.AnimNode.KawaiiPhysics.Debug.LengthRate

DataAsset Improvements

• Bone selection now available through hierarchy picker
• Export button added to save AnimNode Limits settings to DataAssets

See GitHub Discussion #128 for details.

v1.15.x

v1.15.0

• UE 5.4 support
• Performance improvements

See GitHub Discussion #117 for details.

v1.14.x (UE 5.0-5.2 Support)

v1.14.0

BoneConstraint Feature (Experimental)

Added BoneConstraint feature for distance constraints between bones.

Effective for cloth simulation like skirts

• Maintains distance between specified bones (BoneConstraints/Bone1, 2) using XPBD
• Bone Constraint Iteration Count Before/After Collision to specify number of constraint iterations
• Can also be configured in DataAssets
• Bone sets can be specified using regular expressions

Other Improvements

• DataAssets owned by KawaiiPhysics AnimNode can now be pin-exposed
• Planar Limit processing optimized
• Physics processing code refactored

See GitHub Discussion #112 for details.

v1.13.x

v1.13.0

Warm Up Feature

Added physics warm-up feature.

• When Need Warm Up is true and Warm Up Frame is 1 or higher, Warm Up processing is executed
• After execution, Need Warm Up becomes false
• Larger Warm Up Frame values lead to more stability but increase computational load

Warm Up can also be enabled via AnimNode functions added in v1.12.0.

See GitHub Discussion #104 for details.

v1.12.x

v1.12.0

• Added AnimNode functions
• KawaiiPhysics node state can now be dynamically changed from Blueprints

See GitHub Discussion #103 for details.

v1.11.x (UE 4.27 Support)

v1.11.1

• Final version supporting UE 4.27

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For all changes, see GitHub Releases.