phaser/Phaser/system/easing/Elastic.ts

/// <reference path="../../Game.ts" />

/**
 *	Phaser - Easing
 *
 *	@desc 		Based heavily on tween.js by sole (https://github.com/sole/tween.js)
 *
 *	@version 	1.0 - 11th January 2013
 *
 *	@author 	Richard Davey, TypeScript conversion and Phaser integration. See Phaser.TweenManager for the full tween.js author list
 */

module Phaser.Easing {

    export class Elastic {

        public static In(k) {

            var s, a = 0.1, 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));

        }

        public static Out(k) {

            var s, a = 0.1, 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);

        }

        public static InOut(k) {

            var s, a = 0.1, 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;

        }

    }

}