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Debugging

This guide explains how to investigate and resolve KawaiiPhysics issues.

Debug Display​

Collision Visualization​

Collision shapes can be displayed in the editor.

Collision debug display

Supported Collision Shapes​

ShapeDebug DisplayVersion
SphereWireframe sphere-
CapsuleWireframe capsule-
PlanePlane gridImproved in v1.20.0
BoxWireframe boxAdded in v1.20.0

Bone Chain Verification​

You can visually verify which bones have physics applied.

GameplayTag Filtering​

Version Info

Added in v1.17.0, enhanced in v1.20.0

Debug display targets can be filtered using GameplayTags. Useful when you want to debug display only specific characters among many characters.

Common Issues​

Bones Don't Move​

Cause 1: Root Bone setting mistake

  • Physics is not applied to Root Bone itself
  • Verify child bones exist

Cause 2: Extreme parameters

// Stiffness too high
Stiffness = 1.0f; // Almost no movement

// Appropriate value
Stiffness = 0.05f;

Bones Are Erratic​

Cause: Damping too low

// Doesn't converge
Damping = 0.0f;

// Appropriate value
Damping = 0.1f;

Penetrating Through Body​

Cause: Collision not set or too small

  • Verify collision size
  • Verify Driving Bone is correct

Performance Degradation​

  • Verify bone count
  • Verify collision count
  • See Performance

Console Commands​

stat Anim

KawaiiPhysics stats are part of STATGROUP_Anim. Look for entries beginning with KawaiiPhysics_ in the displayed list.

Log Output​

// Enable verbose logging
UE_LOG(LogKawaiiPhysics, Verbose, TEXT("Debug info"));

Reporting Issues​

If the issue persists, please report it on GitHub Issues.

Information to include when reporting:

  • UE version
  • KawaiiPhysics version
  • Steps to reproduce
  • Screenshots/videos