text: function createWorld() {
  	var worldAABB = new b2AABB();
  	worldAABB.minVertex.Set(-1000, -1000);
  	worldAABB.maxVertex.Set(1000, 1000);
  	var gravity = new b2Vec2(0, 300);
  	var doSleep = true;
  	var world = new b2World(worldAABB, gravity, doSleep);
  	createGround(world);
  	createBox(world, 0, 125, 10, 250);
  	createBox(world, 500, 125, 10, 250);
  	return world;
  }
  
  function createGround(world) {
  	var groundSd = new b2BoxDef();
  	groundSd.extents.Set(1000, 50);
  	groundSd.restitution = 0.2;
  	var groundBd = new b2BodyDef();
  	groundBd.AddShape(groundSd);
  	groundBd.position.Set(-500, 340);
  	return world.CreateBody(groundBd)
  }
  
  function createBall(world, x, y) {
  	var ballSd = new b2CircleDef();
  	ballSd.density = 1.0;
  	ballSd.radius = 20;
  	ballSd.restitution = 1.0;
  	ballSd.friction = 0;
  	var ballBd = new b2BodyDef();
  	ballBd.AddShape(ballSd);
  	ballBd.position.Set(x,y);
  	return world.CreateBody(ballBd);
  }
  
  function createBox(world, x, y, width, height, fixed) {
  	if (typeof(fixed) == 'undefined') fixed = true;
  	var boxSd = new b2BoxDef();
  	if (!fixed) boxSd.density = 1.0;
  	boxSd.extents.Set(width, height);
  	var boxBd = new b2BodyDef();
  	boxBd.AddShape(boxSd);
  	boxBd.position.Set(x,y);
  	return world.CreateBody(boxBd)
  }
  
  var demos = {};
  demos.InitWorlds = [];
  