File: src\utils\math\class.vector2D.js

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 *
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/**
 * A 2D vector object
 * @module Math
 * @class CGSGVector2D
 * @extends {Object}
 * @constructor
 * @param {Number} x
 * @param {Number} y
 * @type {CGSGVector2D}
 * @author Gwennael Buchet (gwennael.buchet@gmail.com)
 */
var CGSGVector2D = CGSGObject.extend(
	{
		initialize: function (x, y) {
			/**
			 * @property x
			 * @type {Number}
			 */
			this.x = x;
			/**
			 * @property y
			 * @type {Number}
			 */
			this.y = y;
		},

		/**
		 * @public
		 * @method copy
		 * @return {CGSGVector2D} a new CGSGVector2D, clone of this one
		 */
		copy: function () {
			return new CGSGVector2D(this.x, this.y);
		},

		/**
		 * add to this vector, the value passed in parameter
		 * @public
		 * @method add
		 * @param {CGSGVector2D} vector
		 */
		add: function (vector) {
			this.x += vector.x;
			this.y += vector.y;
		},

		/**
		 * substract to this vector, the value passed in parameter
		 * @public
		 * @method substract
		 * @param {CGSGVector2D} vector
		 */
		substract: function (vector) {
			this.x -= vector.x;
			this.y -= vector.y;
		},

		/**
		 * multiply to this vector, the value passed in parameter
		 * @public
		 * @method multiply
		 * @param {CGSGVector2D} vector
		 */
		multiply: function (vector) {
			this.x *= vector.x;
			this.y *= vector.y;
		},

		/**
		 * divide to this vector, the value passed in parameter
		 * @public
		 * @method divide
		 * @param {CGSGVector2D} vector
		 */
		divide: function (vector) {
			this.x /= vector.x;
			this.y /= vector.y;
		},

		/**
		 * Multiply x and y by f
		 * @public
		 * @method multiplyByFloat
		 * @param {Number} f
		 */
		multiplyByFloat: function (f) {
			this.x *= f;
			this.y *= f;
		},

		/**
		 * Divide x and y by f
		 * @public
		 * @method divideByFloat
		 * @param {Number} f
		 */
		divideByFloat: function (f) {
			this.x /= f;
			this.y /= f;
		},

		/**
		 * Compute the euclidian distance between this vector and the one passe in parameter
		 * @public
		 * @method getDistance
		 * @param {CGSGVector2D} vector
		 * @return {Number}
		 */
		getDistance: function (vector) {
			return Math.sqrt(
				Math.pow(this.x - vector.x, 2) +
				Math.pow(this.y - vector.y, 2)
			);
		},

		/**
		 * rotate this vector around its origin
		 * @public
		 * @method rotate
		 * @param {Number} angle
		 */
		rotate: function (angle) {
			var ca = Math.cos(angle);
			var sa = Math.sin(angle);
			this.x = this.x * ca + this.y * sa;
			this.y = this.x * sa - this.y * ca;
		},

		/**
		 * @public
		 * @method getLength
		 * @return {Number}
		 */
		getLength: function () {
			return Math.sqrt((this.x * this.x) + (this.y * this.y));
		},

		/**
		 * @public
		 * @method getSquaredLength
		 * @return {Number}
		 */
		getSquaredLength: function () {
			return (this.x * this.x) + (this.y * this.y);
		},

		/**
		 * Normalize this vector
		 * @public
		 * @method normalize
		 */
		normalize: function () {
			var scalefactor;
			var length = this.getLength();

			//return if length is 1 or 0
			if (length == 1 || length == 0) {
				return;
			}

			scalefactor = 1.0 / length;
			this.x *= scalefactor;
			this.y *= scalefactor;
		}
	}
);