Tween.js

/**
 * Tween.js - Licensed under the MIT license
 * https://github.com/tweenjs/tween.js
 * ----------------------------------------------
 *
 * See https://github.com/tweenjs/tween.js/graphs/contributors for the full list of contributors.
 * Thank you all, you're awesome!
 */

// Include a performance.now polyfill
(function () {

	if ('performance' in window === false) {
		window.performance = {};
	}

	// IE 8
	Date.now = (Date.now || function () {
		return new Date().getTime();
	});

	if ('now' in window.performance === false) {
		var offset = window.performance.timing && window.performance.timing.navigationStart ? window.performance.timing.navigationStart
		                                                                                    : Date.now();

		window.performance.now = function () {
			return Date.now() - offset;
		};
	}

})();

var TWEEN = TWEEN || (function () {

	var _tweens = [];

	return {

		getAll: function () {

			return _tweens;

		},

		removeAll: function () {

			_tweens = [];

		},

		add: function (tween) {

			_tweens.push(tween);

		},

		remove: function (tween) {

			var i = _tweens.indexOf(tween);

			if (i !== -1) {
				_tweens.splice(i, 1);
			}

		},

		update: function (time) {

			if (_tweens.length === 0) {
				return false;
			}

			var i = 0;

			time = time !== undefined ? time : window.performance.now();

			while (i < _tweens.length) {

				if (_tweens[i].update(time)) {
					i++;
				} else {
					_tweens.splice(i, 1);
				}

			}

			return true;

		}
	};

})();

TWEEN.Tween = function (object) {

	var _object = object;
	var _valuesStart = {};
	var _valuesEnd = {};
	var _valuesStartRepeat = {};
	var _duration = 1000;
	var _repeat = 0;
	var _yoyo = false;
	var _isPlaying = false;
	var _reversed = false;
	var _delayTime = 0;
	var _startTime = null;
        var _pauseTime = null;
	var _easingFunction = TWEEN.Easing.Linear.None;
	var _interpolationFunction = TWEEN.Interpolation.Linear;
	var _chainedTweens = [];
	var _onStartCallback = null;
	var _onStartCallbackFired = false;
	var _onUpdateCallback = null;
	var _onCompleteCallback = null;
	var _onStopCallback = null;

	// Set all starting values present on the target object
	for (var field in object) {
		_valuesStart[field] = parseFloat(object[field], 10);
	}

	this.to = function (properties, duration) {

		if (duration !== undefined) {
			_duration = duration;
		}

		_valuesEnd = properties;

		return this;

	};

	this.start = function (time) {

		TWEEN.add(this);

		_isPlaying = true;

		_onStartCallbackFired = false;

		_startTime = time !== undefined ? time : window.performance.now();
		_startTime += _delayTime;

		for (var property in _valuesEnd) {

			// Check if an Array was provided as property value
			if (_valuesEnd[property] instanceof Array) {

				if (_valuesEnd[property].length === 0) {
					continue;
				}

				// Create a local copy of the Array with the start value at the front
				_valuesEnd[property] = [_object[property]].concat(_valuesEnd[property]);

			}

			// If `to()` specifies a property that doesn't exist in the source object,
			// we should not set that property in the object
			if (_valuesStart[property] === undefined) {
				continue;
			}

			_valuesStart[property] = _object[property];

			if ((_valuesStart[property] instanceof Array) === false) {
				_valuesStart[property] *= 1.0; // Ensures we're using numbers, not strings
			}

			_valuesStartRepeat[property] = _valuesStart[property] || 0;

		}

		return this;

	};
        
        this.pause = function () {
          if (!_isPlaying) {
            return this;
          } 
          _pauseTime = window.performance.now() - _startTime;
          TWEEN.remove (this);
          _isPlaying = false;
          return this;
        };
        
        this.resume = function () {
          if (_isPlaying) {
            return this;
          } 
          _startTime = window.performance.now() - _pauseTime;
          TWEEN.add(this);
          _isPlaying = true;
          return this;
        };
        
        this.restart = function () {
          _startTime = window.performance.now();
          return this;
        }

	this.stop = function () {

		if (!_isPlaying) {
			return this;
		}

		TWEEN.remove(this);
		_isPlaying = false;

		if (_onStopCallback !== null) {
			_onStopCallback.call(_object);
		}

		this.stopChainedTweens();
		return this;

	};

	this.stopChainedTweens = function () {

		for (var i = 0, numChainedTweens = _chainedTweens.length; i < numChainedTweens; i++) {
			_chainedTweens[i].stop();
		}

	};

	this.delay = function (amount) {

		_delayTime = amount;
		return this;

	};

	this.repeat = function (times) {

		_repeat = times;
		return this;

	};

	this.yoyo = function (yoyo) {

		_yoyo = yoyo;
		return this;

	};


	this.easing = function (easing) {

		_easingFunction = easing;
		return this;

	};

	this.interpolation = function (interpolation) {

		_interpolationFunction = interpolation;
		return this;

	};

	this.chain = function () {

		_chainedTweens = arguments;
		return this;

	};

	this.onStart = function (callback) {

		_onStartCallback = callback;
		return this;

	};

	this.onUpdate = function (callback) {

		_onUpdateCallback = callback;
		return this;

	};

	this.onComplete = function (callback) {

		_onCompleteCallback = callback;
		return this;

	};

	this.onStop = function (callback) {

		_onStopCallback = callback;
		return this;

	};

	this.update = function (time) {

		var property;
		var elapsed;
		var value;

		if (time < _startTime) {
			return true;
		}

		if (_onStartCallbackFired === false) {

			if (_onStartCallback !== null) {
				_onStartCallback.call(_object);
			}

			_onStartCallbackFired = true;

		}

		elapsed = (time - _startTime) / _duration;
		elapsed = elapsed > 1 ? 1 : elapsed;

		value = _easingFunction(elapsed);

		for (property in _valuesEnd) {

			// Don't update properties that do not exist in the source object
			if (_valuesStart[property] === undefined) {
				continue;
			}

			var start = _valuesStart[property] || 0;
			var end = _valuesEnd[property];

			if (end instanceof Array) {

				_object[property] = _interpolationFunction(end, value);

			} else {

				// Parses relative end values with start as base (e.g.: +10, -3)
				if (typeof (end) === 'string') {

					if (end.startsWith('+') || end.startsWith('-')) {
						end = start + parseFloat(end, 10);
					} else {
						end = parseFloat(end, 10);
					}
				}

				// Protect against non numeric properties.
				if (typeof (end) === 'number') {
					_object[property] = start + (end - start) * value;
				}

			}

		}

		if (_onUpdateCallback !== null) {
			_onUpdateCallback.call(_object, value);
		}

		if (elapsed === 1) {

			if (_repeat > 0) {

				if (isFinite(_repeat)) {
					_repeat--;
				}

				// Reassign starting values, restart by making startTime = now
				for (property in _valuesStartRepeat) {

					if (typeof (_valuesEnd[property]) === 'string') {
						_valuesStartRepeat[property] = _valuesStartRepeat[property] + parseFloat(_valuesEnd[property], 10);
					}

					if (_yoyo) {
						var tmp = _valuesStartRepeat[property];

						_valuesStartRepeat[property] = _valuesEnd[property];
						_valuesEnd[property] = tmp;
					}

					_valuesStart[property] = _valuesStartRepeat[property];

				}

				if (_yoyo) {
					_reversed = !_reversed;
				}

				_startTime = time + _delayTime;

				return true;

			} else {

				if (_onCompleteCallback !== null) {
					_onCompleteCallback.call(_object);
				}

				for (var i = 0, numChainedTweens = _chainedTweens.length; i < numChainedTweens; i++) {
					// Make the chained tweens start exactly at the time they should,
					// even if the `update()` method was called way past the duration of the tween
					_chainedTweens[i].start(_startTime + _duration);
				}

				return false;

			}

		}

		return true;

	};

};


TWEEN.Easing = {

	Linear: {

		None: function (k) {

			return k;

		}

	},

	Quadratic: {

		In: function (k) {

			return k * k;

		},

		Out: function (k) {

			return k * (2 - k);

		},

		InOut: function (k) {

			if ((k *= 2) < 1) {
				return 0.5 * k * k;
			}

			return - 0.5 * (--k * (k - 2) - 1);

		}

	},

	Cubic: {

		In: function (k) {

			return k * k * k;

		},

		Out: function (k) {

			return --k * k * k + 1;

		},

		InOut: function (k) {

			if ((k *= 2) < 1) {
				return 0.5 * k * k * k;
			}

			return 0.5 * ((k -= 2) * k * k + 2);

		}

	},

	Quartic: {

		In: function (k) {

			return k * k * k * k;

		},

		Out: function (k) {

			return 1 - (--k * k * k * k);

		},

		InOut: function (k) {

			if ((k *= 2) < 1) {
				return 0.5 * k * k * k * k;
			}

			return - 0.5 * ((k -= 2) * k * k * k - 2);

		}

	},

	Quintic: {

		In: function (k) {

			return k * k * k * k * k;

		},

		Out: function (k) {

			return --k * k * k * k * k + 1;

		},

		InOut: function (k) {

			if ((k *= 2) < 1) {
				return 0.5 * k * k * k * k * k;
			}

			return 0.5 * ((k -= 2) * k * k * k * k + 2);

		}

	},

	Sinusoidal: {

		In: function (k) {

			return 1 - Math.cos(k * Math.PI / 2);

		},

		Out: function (k) {

			return Math.sin(k * Math.PI / 2);

		},

		InOut: function (k) {

			return 0.5 * (1 - Math.cos(Math.PI * k));

		}

	},

	Exponential: {

		In: function (k) {

			return k === 0 ? 0 : Math.pow(1024, k - 1);

		},

		Out: function (k) {

			return k === 1 ? 1 : 1 - Math.pow(2, - 10 * k);

		},

		InOut: function (k) {

			if (k === 0) {
				return 0;
			}

			if (k === 1) {
				return 1;
			}

			if ((k *= 2) < 1) {
				return 0.5 * Math.pow(1024, k - 1);
			}

			return 0.5 * (- Math.pow(2, - 10 * (k - 1)) + 2);

		}

	},

	Circular: {

		In: function (k) {

			return 1 - Math.sqrt(1 - k * k);

		},

		Out: function (k) {

			return Math.sqrt(1 - (--k * k));

		},

		InOut: function (k) {

			if ((k *= 2) < 1) {
				return - 0.5 * (Math.sqrt(1 - k * k) - 1);
			}

			return 0.5 * (Math.sqrt(1 - (k -= 2) * k) + 1);

		}

	},

	Elastic: {

		In: function (k) {

			var s;
			var a = 0.1;
			var p = 0.4;

			if (k === 0) {
				return 0;
			}

			if (k === 1) {
				return 1;
			}

			if (!a || a < 1) {
				a = 1;
				s = p / 4;
			} else {
				s = p * Math.asin(1 / a) / (2 * Math.PI);
			}

			return - (a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p));

		},

		Out: function (k) {

			var s;
			var a = 0.1;
			var p = 0.4;

			if (k === 0) {
				return 0;
			}

			if (k === 1) {
				return 1;
			}

			if (!a || a < 1) {
				a = 1;
				s = p / 4;
			} else {
				s = p * Math.asin(1 / a) / (2 * Math.PI);
			}

			return (a * Math.pow(2, - 10 * k) * Math.sin((k - s) * (2 * Math.PI) / p) + 1);

		},

		InOut: function (k) {

			var s;
			var a = 0.1;
			var p = 0.4;

			if (k === 0) {
				return 0;
			}

			if (k === 1) {
				return 1;
			}

			if (!a || a < 1) {
				a = 1;
				s = p / 4;
			} else {
				s = p * Math.asin(1 / a) / (2 * Math.PI);
			}

			if ((k *= 2) < 1) {
				return - 0.5 * (a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p));
			}

			return a * Math.pow(2, -10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p) * 0.5 + 1;

		}

	},

	Back: {

		In: function (k) {

			var s = 1.70158;

			return k * k * ((s + 1) * k - s);

		},

		Out: function (k) {

			var s = 1.70158;

			return --k * k * ((s + 1) * k + s) + 1;

		},

		InOut: function (k) {

			var s = 1.70158 * 1.525;

			if ((k *= 2) < 1) {
				return 0.5 * (k * k * ((s + 1) * k - s));
			}

			return 0.5 * ((k -= 2) * k * ((s + 1) * k + s) + 2);

		}

	},

	Bounce: {

		In: function (k) {

			return 1 - TWEEN.Easing.Bounce.Out(1 - k);

		},

		Out: function (k) {

			if (k < (1 / 2.75)) {
				return 7.5625 * k * k;
			} else if (k < (2 / 2.75)) {
				return 7.5625 * (k -= (1.5 / 2.75)) * k + 0.75;
			} else if (k < (2.5 / 2.75)) {
				return 7.5625 * (k -= (2.25 / 2.75)) * k + 0.9375;
			} else {
				return 7.5625 * (k -= (2.625 / 2.75)) * k + 0.984375;
			}

		},

		InOut: function (k) {

			if (k < 0.5) {
				return TWEEN.Easing.Bounce.In(k * 2) * 0.5;
			}

			return TWEEN.Easing.Bounce.Out(k * 2 - 1) * 0.5 + 0.5;

		}

	}

};

TWEEN.Interpolation = {

	Linear: function (v, k) {

		var m = v.length - 1;
		var f = m * k;
		var i = Math.floor(f);
		var fn = TWEEN.Interpolation.Utils.Linear;

		if (k < 0) {
			return fn(v[0], v[1], f);
		}

		if (k > 1) {
			return fn(v[m], v[m - 1], m - f);
		}

		return fn(v[i], v[i + 1 > m ? m : i + 1], f - i);

	},

	Bezier: function (v, k) {

		var b = 0;
		var n = v.length - 1;
		var pw = Math.pow;
		var bn = TWEEN.Interpolation.Utils.Bernstein;

		for (var i = 0; i <= n; i++) {
			b += pw(1 - k, n - i) * pw(k, i) * v[i] * bn(n, i);
		}

		return b;

	},

	CatmullRom: function (v, k) {

		var m = v.length - 1;
		var f = m * k;
		var i = Math.floor(f);
		var fn = TWEEN.Interpolation.Utils.CatmullRom;

		if (v[0] === v[m]) {

			if (k < 0) {
				i = Math.floor(f = m * (1 + k));
			}

			return fn(v[(i - 1 + m) % m], v[i], v[(i + 1) % m], v[(i + 2) % m], f - i);

		} else {

			if (k < 0) {
				return v[0] - (fn(v[0], v[0], v[1], v[1], -f) - v[0]);
			}

			if (k > 1) {
				return v[m] - (fn(v[m], v[m], v[m - 1], v[m - 1], f - m) - v[m]);
			}

			return fn(v[i ? i - 1 : 0], v[i], v[m < i + 1 ? m : i + 1], v[m < i + 2 ? m : i + 2], f - i);

		}

	},

	Utils: {

		Linear: function (p0, p1, t) {

			return (p1 - p0) * t + p0;

		},

		Bernstein: function (n, i) {

			var fc = TWEEN.Interpolation.Utils.Factorial;

			return fc(n) / fc(i) / fc(n - i);

		},

		Factorial: (function () {

			var a = [1];

			return function (n) {

				var s = 1;

				if (a[n]) {
					return a[n];
				}

				for (var i = n; i > 1; i--) {
					s *= i;
				}

				a[n] = s;
				return s;

			};

		})(),

		CatmullRom: function (p0, p1, p2, p3, t) {

			var v0 = (p2 - p0) * 0.5;
			var v1 = (p3 - p1) * 0.5;
			var t2 = t * t;
			var t3 = t * t2;

			return (2 * p1 - 2 * p2 + v0 + v1) * t3 + (- 3 * p1 + 3 * p2 - 2 * v0 - v1) * t2 + v0 * t + p1;

		}

	}

};

// UMD (Universal Module Definition)
(function (root) {

	if (typeof define === 'function' && define.amd) {

		// AMD
		define([], function () {
			return TWEEN;
		});

	} else if (typeof module !== 'undefined' && typeof exports === 'object') {

		// Node.js
		module.exports = TWEEN;

	} else if (root !== undefined) {

		// Global variable
		root.TWEEN = TWEEN;

	}

})(this);