This file comes from Box2D-JS, Copyright (c) 2008 ANDO Yasushi.
  The original version is available at http://box2d-js.sourceforge.net/ under the
  zlib/libpng license (see License.txt).
  This version has been modified to make it work with O3D.
  
  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(250, 50);
    groundSd.restitution = 0.2;
    var groundBd = new b2BodyDef();
    groundBd.AddShape(groundSd);
    groundBd.position.Set(250, 340);
    // NOTE: Added the following line to create a 3d object to display.
    groundBd.userData = g.mgr.createBox(250, 50);
    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);
    // NOTE: Added the following line to create a 3d object to display.
    ballBd.userData = g.mgr.createCylinder(ballSd.radius);
    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();
    // NOTE: Added the following line to create a 3d object to display.
    boxBd.userData = g.mgr.createBox(width, height);
    boxBd.AddShape(boxSd);
    boxBd.position.Set(x,y);
    return world.CreateBody(boxBd)
  }
  
  var demos = {};
  demos.InitWorlds = [];