PixAnvil/Three.js demo

Er, JavaScript doesn't seem to be running, so basically all you're going to see is the bare code...

// Make a bunch of spheres
var g=new THREE.SphereGeometry(1, 3, 3);
var m=new THREE.MeshLambertMaterial(
    {color: 0xffffff})
sim.nspheres=5;
sim.spheres=[];
for (var i=0;i<sim.nspheres;i++) {
  var s=new THREE.Mesh(g,m);
  s.position.set(0,0,0);
  s.V=new vec3(+20.0*Math.random(),Math.random(),+15.0*Math.random());
  s.P=new vec3(-3.0,0,0);
  s.castShadow=true;
  s.receiveShadow=true;
  scene.add(s); // so it gets rendered
  sim.spheres[i]=s; // so we can animate it
}

// Ground
var groundTex=THREE.ImageUtils.loadTexture( "textures/checkerboard_noisy.jpg" );
groundTex.wrapS=groundTex.wrapT=THREE.RepeatWrapping;
groundTex.repeat=new vec2(25.0,25.0);

sim.ground = new THREE.Mesh(
  new THREE.CubeGeometry(50,50,0.0001),
  new THREE.MeshLambertMaterial(
    {color: 0xffccaa, opacity: 1, map:groundTex})
);
sim.ground.position.z=-1;  /* hack for radius 1 */
sim.ground.receiveShadow=true;
scene.add(sim.ground);

// Sun-like spotlight
var l=new THREE.SpotLight();
sim.light = l;
l.position.set( -50, -100, 100 );
l.castShadow=true;
l.shadowCameraNear = 50; 
l.shadowCameraFar = 500; 
l.shadowCameraFov = 10; // degrees field of view
scene.add(l);

camera.lookAt(scene.position);

/**
  s: sphere object, with s.P position and s.V velocity.
  N: surface normal, facing out of region.
  P: point on surface of boundary region.
*/
function boundaryBounce(s,N,P) {
  N.normalize();
  var rP=s.P.m(P); // sphere position, relative to boundary
  var d=rP.dot(N);
  if (d>0.0) { // we hit the boundary
    s.P.pe(N.t(-d)); // move inside
    var dV=s.V.dot(N); 
    if (dV>0.0) { // flip velocity
      s.V.pe(N.t(-2.0*dV ));
    }
    s.V.te(0.6); // bounce friction (inelastic)
    if (dV>0.3) { // CLANG! the camera

camera.position.pe(N.t(-dV*0.005)); 
    }

}
}

//camera.position.set(0,-10,1.7); // default: assume no "clang!".
for (var i=0;i<sim.nspheres;i++) {
  var s=sim.spheres[i];
  var A=new vec3(0,0,-9.8); 
  s.V.pe(A.t(lib.dt));
  s.P.pe(s.V.t(lib.dt));

boundaryBounce(s,new vec3(0,0,-1), new vec3()); // floor
  boundaryBounce(s,new vec3(+1,0,0), new vec3(5,0,0));
  boundaryBounce(s,new vec3(-1,0,0), new vec3(-4,0,0));
  boundaryBounce(s,new vec3(0,0,+1), new vec3(0,0,5)); // lid

s.position=s.P; // copy to 3D display
}