Collision Proxy skill

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