window.onload = function() {
  'use strict';

  // create a Scene
  var scn = new DivSugar.Scene().setSize(800, 600).setImage('mobile-sugar-examples-assets-sunset.jpg').appendTo(document.body);

  // maximize the Scene size
  function resize() { scn.adjustLayout(window.innerWidth, window.innerHeight, 'contain'); }
  window.addEventListener('resize', resize, true);
  resize();

  // define an animation class which inherits the Task class
  function Coin() {
    // call the base class's constructor
    this.constructor.uber.constructor();

    this.vec = new DivSugar.Vector();
    this.pos = new DivSugar.Vector(Math.random() * 800, 900, Math.random() * 800 - 1000);
    this.vel = new DivSugar.Vector(Math.random() * 6 - 3, Math.random() * 8 - 20, Math.random() * 6 - 3);
    this.rot = new DivSugar.Vector(Math.random() * 0.1, Math.random() * 0.1, Math.random() * 0.1);

    this.center = new DivSugar.Node().setPosition(this.pos)
      .rotate(Math.random() * 360, Math.random() * 360, Math.random() * 360).appendTo(scn);

    this.front = new DivSugar.Node().setSize(200, 200).setPosition(-100, -100, 0).setBackface(false)
      .setImage('mobile-sugar-examples-assets-coin.png').setImageClip(0, 0, 0.5, 1).appendTo(this.center);

    this.back = new DivSugar.Node().setSize(200, 200).setPosition(100, -100, 0).setBackface(false)
      .setImage('mobile-sugar-examples-assets-coin.png').setImageClip(0.5, 0, 1, 1).rotate(0, 180, 0).appendTo(this.center);
  }

  DivSugar.inherit(Coin, DivSugar.Task);

  Coin.prototype.onUpdate = function() {
    this.vel.y += this.deltaTime * 0.01;
    this.pos.add(this.vec.set(this.vel).mul(this.deltaTime * 0.06));
    this.center.setPosition(this.pos).rotate(this.deltaTime * this.rot.x, this.deltaTime * this.rot.y, this.deltaTime * this.rot.z);

    // when fall enough, destroy this Task and create an another Task
    if (this.pos.y > 1000) {
      this.destroy();
      new Coin().appendTo(DivSugar.rootTask);
    }
  };

  Coin.prototype.onDestroy = function() { scn.remove(this.center); };

  // create and register instances of the animation class
  for (var i = 0; i < 30; i++) { new Coin().appendTo(DivSugar.rootTask); }
};