lazd / cannon.js

A lightweight 3D physics engine written in JavaScript.

cannon.js

Lightweight 3D physics for the web

Inspired by three.js and ammo.js, and driven by the fact that the web lacks a physics engine, here comes cannon.js. The rigid body physics engine includes simple collision detection, various body shapes, contacts, friction and constraints.

Demos - Documentation - Rendering hints - NPM package

Usage

Optionally, start by building the library using Grunt.

Include build/cannon.js in your html:

<script src="cannon.js"></script>

Then you can start experimenting.

The sample code below creates a sphere on a plane, steps the simulation, and prints the sphere simulation to the console. Note that Cannon.js uses SI units (metre, kilogram, second, etc.).

// Setup our world
var world = new CANNON.World();
world.gravity.set(0,0,-9.82); // m/s²
world.broadphase = new CANNON.NaiveBroadphase();

// Create a sphere
var radius = 1; // m
var sphereBody = new CANNON.Body({
   mass: 5 // kg
});
var sphereShape = new CANNON.Sphere(radius);
sphereBody.addShape(sphereShape);
sphereBody.position.set(0,0,10); // m
world.add(sphereBody);

// Create a plane
var groundBody = new CANNON.Body({
    mass: 0 // mass == 0 makes the body static
});
var groundShape = new CANNON.Plane();
groundBody.addShape(groundShape);
world.add(groundBody);

// Step the simulation
setInterval(function(){
  var timeStep = 1.0/60.0; // seconds
  world.step(timeStep);
  console.log("Sphere z position: " + sphereBody.position.z);
}, 1000.0/60.0);

If you want to know how to use cannon.js with a rendering engine, for example Three.js, see the Examples.

Features

• Rigid body physics
• Collision detection (no CCD)
• Contacts with friction and restitution
• Constraints
  • PointToPoint (also called balljoint)
  • Distance
  • Hinge (with optional motor)
• Gauss-Seidel constraint solver and an island split algorithm
• Collision filters
• Body motion states (dynamic, kinematic, static)
• Body sleeping
• Experimental SPH / fluid support
• Various shapes and collisions (see table below)

	Sphere	Plane	Box	Convex	Particle	Heightfield
Sphere	Yes	Yes	Yes	Yes	Yes	Yes
Plane	-	-	Yes	Yes	Yes	-
Box	-	-	Yes	Yes	Yes	Yes
Cylinder	-	-	Yes	Yes	Yes	Yes
Convex	-	-	-	Yes	Yes	Yes
Particle	-	-	-	-	-	(todo)
Heightfield	-	-	-	-	-	-

Todo

The simpler todos are marked with @todo in the code. Github Issues can and should also be used for todos.

Help

Create an issue on here if you need help.