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.compound = {};
  demos.compound.createCompoundBall = function(world, x, y) {
    var ballSd1 = new b2CircleDef();
    ballSd1.density = 1.0;
    ballSd1.radius = 20;
    ballSd1.restitution = 0.2;
    ballSd1.localPosition.Set(-20, 0);
    var ballSd2 = new b2CircleDef();
    ballSd2.density = 1.0;
    ballSd2.radius = 20;
    ballSd2.restitution = 0.2;
    ballSd2.localPosition.Set(20, 0);
    var ballBd = new b2BodyDef();
    ballBd.AddShape(ballSd1);
    ballBd.AddShape(ballSd2);
    ballBd.position.Set(x, y);
    // NOTE: Added the following line to create a 3d object to display.
    ballBd.userData = g.mgr.createCompoundCylinder(20, -20, 20, 20);
    return world.CreateBody(ballBd);
  }
  
  demos.compound.createCompoundPoly = function(world, x, y) {
    var points = [[-30, 0], [30, 0], [0, 15]];
    var polySd1 = new b2PolyDef();
    polySd1.vertexCount = points.length;
    for (var i = 0; i < points.length; i++) {
      polySd1.vertices[i].Set(points[i][0], points[i][1]);
    }
    polySd1.localRotation = 0.3524 * Math.PI;
    var R1 = new b2Mat22(polySd1.localRotation);
    polySd1.localPosition = b2Math.b2MulMV(R1, new b2Vec2(30, 0));
    polySd1.density = 1.0;
    var polySd2 = new b2PolyDef();
    polySd2.vertexCount = points.length;
    for (var i = 0; i < points.length; i++) {
      polySd2.vertices[i].Set(points[i][0], points[i][1]);
    }
    polySd2.localRotation = -0.3524 * Math.PI;
    var R2 = new b2Mat22(polySd2.localRotation);
    polySd2.localPosition = b2Math.b2MulMV(R2, new b2Vec2(-30, 0));
    var polyBd = new b2BodyDef();
    polyBd.AddShape(polySd1);
    polyBd.AddShape(polySd2);
    polyBd.position.Set(x,y);
    // NOTE: Added the following line to create a 3d object to display.
    polyBd.userData = g.mgr.createCompoundWedge(points,
                                                polySd1.localPosition,
                                                polySd1.localRotation,
                                                points,
                                                polySd2.localPosition,
                                                polySd2.localRotation);
    return world.CreateBody(polyBd)
  }
  
  demos.compound.initWorld = function(world) {
    var i;
    for (i = 1; i <= 4; i++) {
      demos.compound.createCompoundPoly(world, 150 + 3 * Math.random(), 40 * i);
    }
    for (i = 1; i <= 4; i++) {
      demos.compound.createCompoundBall(world, 350 + 3 * Math.random(), 45 * i);
    }
  }
  demos.InitWorlds.push(demos.compound.initWorld);