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
- Slightly smaller than visual mesh to reduce snagging (project-dependent)
- No holes; watertight convex pieces
- Apply scale
- Origin aligned with render mesh
- 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 |
