Unity 3D Collision Debugging
/physics-3d-collision
Diagnoses 3D PhysX collision and trigger problems.
- GitHub stars
- 1,118 (repository stars as of 2026-10-21)
- License
- Unity Companion License
- Last commit
- 2026/10/20
- By
- Unity Technologies
Part of
Unity Skills (official)
Unity's own collection of skills for AI coding agents: prompts, slash commands and tools built for Unity workflows.
Listed from the author's README. GameSkill has not run this end to end yet. Agent support and install steps are as documented by the author.
Install
npx skills add Unity-Technologies/skills --skill physics-3d-collisionInstalls only this skill. Add -a claude-code (puts it in .claude/skills/), -a codex or -a cursor (.agents/skills/) to choose the agent, and -g to install it for your user instead of the project.
Commands are copied from the project's README. Check the repository before running anything on your machine.
Install for a specific agent
| Agents | -a | Folder |
|---|---|---|
| Claude Code | claude-code | .claude/skills/ |
| Codex | codex | .agents/skills/ |
| Cursor | cursor | .agents/skills/ |
| Gemini CLI | gemini-cli | .agents/skills/ |
| GitHub Copilot | github-copilot | .agents/skills/ |
| OpenCode | opencode | .agents/skills/ |
| Windsurf | windsurf | .windsurf/skills/ |
Add -a <flag> to the command. These are project folders; add -g to install for your user account instead.
What you get
- Worked steps: Identify Your Symptom; Collision Callback Checklist
- A verification step before the work is called done
- Bundled 1 reference doc and 1 supporting file the agent reads when needed
Good fit
- OnCollisionEnter or OnTriggerEnter doesn't fire, objects pass through each other, raycasts miss, or a MeshCollider misbehaves
Try this prompt
OnTriggerEnter never fires on my pickup. Find out why.About this skill
Diagnoses 3D PhysX collision and trigger problems. Use when OnCollisionEnter or OnTriggerEnter doesn't fire, objects pass through each other, raycasts miss, or a MeshCollider misbehaves. Also answers 2D and DOTS physics best-effort if no dedicated skill is available.
From the physics-3d-collision SKILL.md in Unity-Technologies/skills.
What's inside
- CRITICAL FACT (read first, do not override)
- Required Output -- non-negotiable
- STOP CHECK -- match before any tool call
- Fast-Path 1 -- 2D physics (best-effort, outside primary scope)
- Fast-Path 2 -- DOTS / ECS / Unity Physics package (best-effort, outside primary scope)
- Fast-Path 3 -- Two kinematic triggers not firing OnTriggerEnter
- Fast-Path 4 -- Ragdoll explodes on frame 1 with no applied forces
- Fast-Path 5 -- CharacterController + OnCollisionEnter not firing
- Fast-Path 6 -- AddForce stopped working after object settled
- Fast-Path 7 -- All physics frozen but raycasts still work
Good to know
Maintained and published by Unity. Many skills drive the open Unity Editor through the Unity CLI instead of editing scene files by hand.
Requirements
- A Unity project
- Unity CLI (recommended: many skills drive the open Editor through it)
FAQ
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