openprivacy / 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 - CDN

Browser install

Just include cannon.js or cannon.min.js in your html and you're done:

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

Node.js install

Install the cannon package via NPM:

npm install --save cannon

Alternatively, point to the Github repo directly to get the very latest version:

npm install --save schteppe/cannon.js

Example

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

// Create a sphere
var radius = 1; // m
var sphereBody = new CANNON.Body({
   mass: 5, // kg
   position: new CANNON.Vec3(0, 0, 10), // m
   shape: new CANNON.Sphere(radius)
});
world.addBody(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.addBody(groundBody);

var fixedTimeStep = 1.0 / 60.0; // seconds
var maxSubSteps = 3;

// Start the simulation loop
var lastTime;
(function simloop(time){
  requestAnimationFrame(simloop);
  if(lastTime !== undefined){
     var dt = (time - lastTime) / 1000;
     world.step(fixedTimeStep, dt, maxSubSteps);
  }
  console.log("Sphere z position: " + sphereBody.position.z);
  lastTime = time;
})();

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

Features

• Rigid body dynamics
• Discrete collision detection
• Contacts, friction and restitution
• Constraints
  • PointToPoint (a.k.a. ball/socket joint)
  • Distance
  • Hinge (with optional motor)
  • Lock
  • ConeTwist
• Gauss-Seidel constraint solver and an island split algorithm
• Collision filters
• Body sleeping
• Experimental SPH / fluid support
• Various shapes and collision algorithms (see table below)

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

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 if you need help.