matterjs-physics

name	matterjs-physics
description	Implement 2D physics interactions with Matter.js — Engine/World setup, Render/Runner configuration, adding bodies and constraints, mouse interaction, and SPA cleanup patterns.
metadata	{"openclaw":{"emoji":"⚛️","source":"https://github.com/MengTo/Skills"}}

Matter.js — 2D Physics Skill

When to use

• Interactive 2D physics: falling objects, drag interactions, physics-based UI elements
• Canvas-based simulations and games
• Fun, playful UI moments with real physics

Minimal setup

<script>
  const { Engine, Render, Runner, Bodies, Composite } = Matter;
  const engine = Engine.create();
  const render = Render.create({
    element: document.body, engine,
    options: { width: 800, height: 600, wireframes: false }
  });
  Runner.run(Runner.create(), engine);
  Render.run(render);
  const ground = Bodies.rectangle(400, 610, 810, 60, { isStatic: true });
  const box = Bodies.rectangle(400, 200, 80, 80);
  Composite.add(engine.world, [ground, box]);
</script>

Mouse interaction

const { Mouse, MouseConstraint } = Matter;
const mouse = Mouse.create(render.canvas);
const mc = MouseConstraint.create(engine, { mouse });
Composite.add(engine.world, mc);
render.mouse = mouse;

Common patterns

• Composite.add(engine.world, [...]) to add bodies
• render.options.wireframes = false for solid rendering
• Runner.run(runner, engine) for a simple loop

Cleanup (SPA)

• Runner.stop(runner) — stop simulation
• Remove render canvas from DOM
• Clear engine and world references

Tips for AI Agents

• Ask about viewport size and scaling for the canvas.
• Confirm rendering approach (Matter.Render vs custom renderer).
• Check if mouse/touch drag interaction is needed.