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.
  
  demos.top = {};
  demos.top.createBall = function(world, x, y, rad, fixed) {
    var ballSd = new b2CircleDef();
    if (!fixed) ballSd.density = 1.0;
    ballSd.radius = rad || 10;
    ballSd.restitution = 0.2;
    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);
  };
  demos.top.createPoly = function(world, x, y, points, fixed) {
    var polySd = new b2PolyDef();
    if (!fixed) polySd.density = 1.0;
    polySd.vertexCount = points.length;
    for (var i = 0; i < points.length; i++) {
      polySd.vertices[i].Set(points[i][0], points[i][1]);
    }
    var polyBd = new b2BodyDef();
    if (points.length == 3) {
      // NOTE: Added the following line to create a 3d object to display.
      polyBd.userData = g.mgr.createWedge(points);
    }
    polyBd.AddShape(polySd);
    polyBd.position.Set(x,y);
    return world.CreateBody(polyBd)
  };
  demos.top.initWorld = function(world) {
    demos.top.createBall(world, 350, 100, 50, true);
    demos.top.createPoly(world, 100, 100, [[0, 0], [10, 30], [-10, 30]], true);
    demos.top.createPoly(world, 150, 150, [[0, 0], [10, 30], [-10, 30]], true);
    var pendulum = createBox(world, 150, 100, 20, 20, false);
    var jointDef = new b2RevoluteJointDef();
    jointDef.body1 = pendulum;
    jointDef.body2 = world.GetGroundBody();
    jointDef.anchorPoint = pendulum.GetCenterPosition();
    world.CreateJoint(jointDef);
  
    var seesaw = demos.top.createPoly(world, 300, 200, [[0, 0], [100, 30], [-100, 30]]);
    jointDef.body1 = seesaw;
    jointDef.anchorPoint = seesaw.GetCenterPosition();
    world.CreateJoint(jointDef);
  };
  demos.InitWorlds.push(demos.top.initWorld);