);
  var rotationSpeed = 1.2;

  var x = 0;
  var y = 0;
  var dx = 4;
  var dy = 4;

  var then = 0;

  requestAnimationFrame(drawScene);

  function drawScene(time) {
    // Convert to seconds
    var now = time * 0.001;
    // Subtract the previous time from the current time
    var deltaTime = now - then;
    // Remember the current time for the next frame.
    then = now;

    webglUtils.resizeCanvasToDisplaySize(gl.canvas);

    x += dx;
    y += dy;
    if (x < 0 || x > gl.canvas.width) {
      dx = 