Chipmunk 2d physics engine, in Javascript

Chipmunk for Javascript!

This is a port of the Chipmunk Physics library to Javascript!

Check out the sexy demos! (Surprisingly, works best in Safari)

  • It is slower than the C version (duh, its in javascript). Specifically, physics simulations using chipmunk-js runs about 3 times slower than the C equivalent.
  • I haven't implemented chipmunk's spatial hash, and I have no intention to do so.
  • The feature set is lagged a little from the real Chipmunk library. Chipmunk-js currently corresponds to Chipmunk 6.1.1 published in August 2012.


The API for Chipmunk-js is almost identical to chipmunk-physics. Except:

  • The cp prefix has gone

  • Most functions are wrapped by their containing objects

  • Some functions took an array-and-length. Arrays are now all simply javascript arrays, and the length argument has been removed. Eg:

cpMomentForPoly(mass, numVerts, *verts, offset); ```



cp.momentForPoly(mass, verts, offset); ```

  • Lots of trivial getters and setters have been removed.
  • Lists of verticies are described using a flattened JS array of [x1,y1,x2,y2,...] instead of an array of objects. Ie, [0,0, 0,1, 1,1, 1,0] instead of [cp.v(0,0), cp.v(0,1), cp.v(1,1), cp.v(1,0)].
<script src="cp.min.js"></script>
var space = new cp.Space();
space.addBody(new cp.Body(...))
// ...

If any exceptions are thrown or anything, use cp.js instead of cp.min.js and post the stack trace you get to the issue page.

npm install chipmunk

cp = require('chipmunk');
var space = new cp.Space();
space.addBody(new cp.Body(...))
// ... 


This code creates a new space, sets 10 physics iterations per update (these increase simulation stability). Then it adds a bunch of line segments to the space.

In C, this code looked like:

  cpSpace *space = cpSpaceNew();
  space->iterations = 10;
  cpVect offset = cpv(-320, -240);
  for(int i=0; i<(bouncy_terrain_count - 1); i++){
    cpVect a = bouncy_terrain_verts[i], b = bouncy_terrain_verts[i+1];
    cpShape *shape = cpSpaceAddShape(space, cpSegmentShapeNew(cpSpaceGetStaticBody(space), cpvadd(a, offset), cpvadd(b, offset), 0.0f));
    cpShapeSetElasticity(shape, 1.0f);

In javascript, the equivalent code is:

  var space = new cp.Space();
  space.iterations = 10;
  var offset = cp.v(-320, -240);
  for(var i=0; i<(bouncy_terrain_verts.length - 1); i++){
    var a = bouncy_terrain_verts[i], b = bouncy_terrain_verts[i+1];
    var shape = space.addShape(new cp.SegmentShape(space.staticBody, cp.vadd(a, offset), cp.vadd(b, offset), 0));


Like Chipmunk, chipmunk-js is MIT licensed.

Copyright (c) 2007 Scott Lembcke and Joseph Gentle
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