Calculate the easing pattern
/**
* Calculate the easing pattern
* @private
* @link https://gist.github.com/gre/1650294
* @param {String} type Easing pattern
* @param {Number} time Time animation should take to complete
* @returns {Number}
*/
var easingPattern = function ( type, time ) {
var pattern;
if ( type === 'easeInQuad' ) pattern = time * time; // accelerating from zero velocity
if ( type === 'easeOutQuad' ) pattern = time * (2 - time); // decelerating to zero velocity
if ( type === 'easeInOutQuad' ) pattern = time < 0.5 ? 2 * time * time : -1 + (4 - 2 * time) * time; // acceleration until halfway, then deceleration
if ( type === 'easeInCubic' ) pattern = time * time * time; // accelerating from zero velocity
if ( type === 'easeOutCubic' ) pattern = (--time) * time * time + 1; // decelerating to zero velocity
if ( type === 'easeInOutCubic' ) pattern = time < 0.5 ? 4 * time * time * time : (time - 1) * (2 * time - 2) * (2 * time - 2) + 1; // acceleration until halfway, then deceleration
if ( type === 'easeInQuart' ) pattern = time * time * time * time; // accelerating from zero velocity
if ( type === 'easeOutQuart' ) pattern = 1 - (--time) * time * time * time; // decelerating to zero velocity
if ( type === 'easeInOutQuart' ) pattern = time < 0.5 ? 8 * time * time * time * time : 1 - 8 * (--time) * time * time * time; // acceleration until halfway, then deceleration
if ( type === 'easeInQuint' ) pattern = time * time * time * time * time; // accelerating from zero velocity
if ( type === 'easeOutQuint' ) pattern = 1 + (--time) * time * time * time * time; // decelerating to zero velocity
if ( type === 'easeInOutQuint' ) pattern = time < 0.5 ? 16 * time * time * time * time * time : 1 + 16 * (--time) * time * time * time * time; // acceleration until halfway, then deceleration
return pattern || time; // no easing, no acceleration
};