audventure/scripts/util.js

function createSound(name, url) {
  var deferred = Q.defer();
  soundManager.createSound({
    id: name,
    url: url,
    autoLoad: true,
    onload: function() {
      deferred.resolve(this);
    }
  });
  return deferred.promise;
}

function sign(x) { return x > 0 ? 1 : x < 0 ? -1 : 0; }

function lerp(from, to, p) {
  return to * p + from * (1 - p);
}

function ease(v) { return v * v * (3 - 2 * v); }

function easeLinear(t, b, c, d) {
  return lerp(b, c, t/d);
}

function easeOutExpo(t, b, c, d) {
  return (t==d) ? b+c : c * (-Math.pow(2, -10 * t/d) + 1) + b;
}

function color(r,g,b,a) {
  return 'rgba('+r+','+g+','+b+','+a.toFixed(5)+')';
}

// Ticker
var Ticker = {};
(function(Ticker) {
  var listeners = [];

  Ticker.addListener = function(listener) {
    listeners.push(listener);
  }

  Ticker.removeListener = function(listener) {
    var index = listeners.indexOf(listener);
    listeners.splice(index, 1);
  }

  var nextFrame =
    window.requestAnimationFrame ||
      window.webkitRequestAnimationFrame ||
      window.mozRequestAnimationFrame ||
      function (callback) {
        setTimeout(function () {
          callback(Date.now())
        }, 10)
      };

  var then = Date.now();
  function tick(now) {
    var delta = (now - then) / 1000;
    listeners.forEach(function(listener){
      listener(delta);
    })
    then = now;
    nextFrame(tick);
  }

  Ticker.start = function() {
    nextFrame(tick);
  }
})(Ticker);

// Tweens
function BaseTween() {}
BaseTween.prototype.animate = function() {
  var self = this;
  function tick(dt) {
    self.update(dt);
  }
  Ticker.addListener(tick);
  self.promise.then(function() {
    Ticker.removeListener(tick);
  });
  self.update(0);
  return self;
};

function Tween(duration, start, end, easing) {
  this.duration = duration;
  this.start = start;
  this.end = end;
  this.easing = easing || easeLinear;
  this.deferred = Q.defer();
  this.timer = 0;
  this.promise = this.deferred.promise;
};

Tween.prototype = new BaseTween();

Tween.prototype.update = function(dt) {
  this.timer += dt;
  if(this.timer >= this.duration) {
    this.timer = this.duration;
    this.deferred.resolve();
  }
  this.value = this.easing(this.timer, this.start, this.end, this.duration);
};

function PromiseTween(value, promise) {
  this.value = value;
  this.promise = promise;
}

PromiseTween.prototype.update = function() {};

function ComposedTween(tweens) {
  this.tweens = tweens;
  this.promise = Q.all(this.tweens.map(function(t) { return t.promise }));
  this.switch(0);
}

ComposedTween.prototype = new BaseTween();

ComposedTween.prototype.switch = function(index) {
  if(index >= this.tweens.length) return;
  var self = this;
  this.current = index;
  this.tweens[index].promise.then(function() {
    self.switch(index + 1);
  });
};

ComposedTween.prototype.update = function(dt) {
  if(this.current >= this.tweens.length) return;
  var active = this.tweens[this.current];
  active.update(dt);
  this.value = active.value;
};

function DeferredTween(start) {
  this.lastTarget = start;
  this.tweens = [];
}

DeferredTween.prototype = new BaseTween();

DeferredTween.prototype.addTween = function(tween) {
  this.tweens.push(tween);
  this.tween = new ComposedTween(this.tweens);
  this.promise = this.tween.promise;
  return this;
}

DeferredTween.prototype.to = function(target, duration, easing) {
  easing = easing || easeLinear;
  this.addTween(new Tween(duration, this.lastTarget, target, easing));
  this.lastTarget = target;
  return this;
};

DeferredTween.prototype.wait = function(duration) {
  return this.to(this.lastTarget, duration);
};

DeferredTween.prototype.waitFor = function(promise) {
  return this.addTween(new PromiseTween(this.lastTarget, promise));
};

DeferredTween.prototype.update = function(dt) {
  this.tween.update(dt);
  this.value = this.tween.value;
};

Tween.from = function(start) {
  return new DeferredTween(start);
};