/collision-proxy

name: collision-proxy
description: Collision proxy authoring for games including UCX/UHX naming, convex hulls, capsules, and simple collider meshes in Blender via MCP.
license: MIT
metadata:
  author: https://github.com/arjun988
  version: "1.0.0"
  domain: blender
  role: specialist
  triggers: collision, collider, UCX, UHX, convex hull, physics proxy, hitbox, blocking volume
  related-skills: lod-pipeline, unity-export, unreal-export, asset-optimization, physics-sim

Collision Proxy

Simple, stable colliders. Prefer primitives and convex pieces over render mesh.

When to Use

• Game physics / blocking volumes
• Unreal UCX export
• Unity mesh or primitive colliders
• Hitboxes for interactables

Workflow

Identify collision needs → Build proxies → Name correctly
  → Test overlaps → Export with render mesh

Collider Types

| Type | Use | |------|-----| | Box | Crates, walls, simple props | | Capsule | Characters, poles | | Sphere | Balls, soft approximates | | Convex hull | Organic / irregular single body | | Multiple convex (UCX) | Vehicles, complex props |

Unreal Naming

UCX_SM_Asset_01
UCX_SM_Asset_02

• Must match associated mesh naming rules for auto-association
• Convex only for UCX

Unity Notes

• Prefer engine primitives when possible
• Mesh colliders: convex toggle for dynamic rigidbodies
• Keep proxy collection exportable

Authoring Rules

1. Slightly smaller than visual mesh to reduce snagging (project-dependent) 2. No holes; watertight convex pieces 3. Apply scale 4. Origin aligned with render mesh 5. Collection: `COL_Collision_[Asset]`

Validation

• [ ] Player cannot fall through intended blockers
• [ ] No huge invisible walls beyond mesh
• [ ] Wheel/character capsules oriented correctly
• [ ] Named for target engine

Constraints

MUST DO

• Prefer few simple shapes over one complex mesh
• Match engine naming conventions
• Keep proxies in dedicated collection

MUST NOT DO

• Use render LOD0 as physics mesh by default
• Non-convex UCX for Unreal auto-convex workflows

Reference Guide

| Topic | Reference | Load When | |-------|-----------|----------| | Collider Recipes | `references/collider-recipes.md` | When needed | | Engine Naming | `references/engine-naming.md` | When needed |