Unity Collider Optimizer

This package is meant for:

• MeshCollider optimization (3D) via bundled gltfpack binaries

  Original Mesh	Unity Mesh Collider	Optimized Mesh Collider
  Tris, Verts Count	3032 tris, 2512 verts	918 tris, 592 verts

• PolygonCollider2D optimization (2D) using RDP line simplification

  Original Sprite	Unity Polygon Collider	Optimized Polygon Collider
  Path Count	214 paths	23 paths

Requirements

• Unity 2020.2 or newer recommended (for MeshColliderCookingOptions)
• A glTF/GLB importer package in your project:
  • com.unity.cloud.gltfast (glTFast) or
  • com.unity.formats.glTF (UnityGLTF)
• Supported OS for the included gltfpack binaries:
  • Windows
  • macOS (Intel & Apple Silicon)
  • Linux

Note

If you don’t have a GLB importer, the tool can’t re-import the simplified mesh and will log an error telling you to install one

Usage

Install

• Download the collider-opt-pkg-v005.unitypackage package from the Releases section and import in your Unity project
• Follow the prompt to install the glTF/GLB importer
• (macOS/Linux) If the gltfpack binary isn’t executable, the tool will attempt to chmod +x automatically

Optimize Colliders

• Select a GameObject with a MeshCollider (3D) or PolygonCollider2D (2D)
• Open context menu by right clicking the component header -> Optimize Collider
• If needed you have option to Load/Save/Reset Collider aswell

Adjust Params

• To adjust params for the optimizer go to Tools -> Collider Optimizer
• Mesh Optimization Params:
  • Contraction : higher contraction -> fewer triangles kept
  • Recalc Normals : recalculate normals after import
  • Convex : sets MeshCollider.convex = true (Unity may auto-reduce to ≤255 tris)
  • Aggressive (-sa) : simplifies aggressively (more tris reduced)
  • Permissive (-sp) : simplifies permissively (less tris reduced)
• Polygon Optimization Params:
  • Tolerance : maximum perpendicular distance new path is allowed to deviate from the original path (higher tolerance -> fewer lines kept)
  • Tolerance Mode :
    • World : interpreted in world units
    • Relative : interpreted as fraction of per-path bbox diagonal
  • Scale By Bounds : In World mode, multiply tolerance by each path’s bounds diagonal (useful for differently sized shapes)

Presets

• You get the option to define presets for different param sets you'd like to save
• Create presets via Assets -> Create -> ColliderOptimizer -> Mesh Preset or Poly Preset
• In Tools -> Collider Optimizer window assign these presets to make them active
• Without an active preset the settings are stored in Project Settings at ProjectSettings/ColliderOptimizerSettings.asset
• Reset to Defaults will update the preset (if assigned) or the project settings to the default values

coll-opt-tut-lo.mp4

Performance Comparison

Polygon.Collider.Comparision.mp4

Mesh.Collider.Comparision.mp4

Gotchas

• For skinned meshes, the tool bakes a static combined mesh for collider usage (as intended for physics), not skinning, anyways I won't use a MeshCollider for a skinned mesh
• Extremely degenerate or non-triangular topologies are skipped
• glb import produced no loadable assets
  Install/reinstall a GLB importer package (UnityGLTF or glTFast) & reoptimize
• Unity limits convex colliders to ≤255 tris, it may auto-simplify further
• If you see warnings about very large triangles (>500 units), check your model scale. The tool bakes transforms, but mismatched import scales can still yield oversized geometry
• The tool attempts to chmod +x the gltfpack binary, if gatekeeper still blocks it, allow it in System Settings or remove quarantine attributes manually

Contribution

Contributions to the project are welcome, consider making a PR

License

MIT License