easing.js

/*
 * Easing Functions - inspired from http://gizma.com/easing/
 * only considering the t value for the range [0, 1] => [0, 1]
 * Finally! Someone who understands we don't need to put the 
 * start, end, duration, etc. into the easing forumlae.
 */
var EasingFunctions = {
	// no easing, no acceleration
	linear: function (t) { return t },
	
	// accelerating from zero velocity
	easeInQuad: function (t) { return t*t },
	// decelerating to zero velocity
	easeOutQuad: function (t) { return t*(2-t) },
	// acceleration until halfway, then deceleration
	easeInOutQuad: function (t) { return t<.5 ? 2*t*t : -1+(4-2*t)*t },
	
	// accelerating from zero velocity 
	easeInCubic: function (t) { return t*t*t },
	// decelerating to zero velocity 
	easeOutCubic: function (t) { return (--t)*t*t+1 },
	// acceleration until halfway, then deceleration 
	easeInOutCubic: function (t) { return t<.5 ? 4*t*t*t : (t-1)*(2*t-2)*(2*t-2)+1 },
	
	// accelerating from zero velocity 
	easeInQuart: function (t) { return t*t*t*t },
	// decelerating to zero velocity 
	easeOutQuart: function (t) { return 1-(--t)*t*t*t },
	// acceleration until halfway, then deceleration
	easeInOutQuart: function (t) { return t<.5 ? 8*t*t*t*t : 1-8*(--t)*t*t*t },
	
	// accelerating from zero velocity
	easeInQuint: function (t) { return t*t*t*t*t },
	// decelerating to zero velocity
	easeOutQuint: function (t) { return 1+(--t)*t*t*t*t },
	// acceleration until halfway, then deceleration 
	easeInOutQuint: function (t) { return t<.5 ? 16*t*t*t*t*t : 1+16*(--t)*t*t*t*t },
	
	// accelerating from zero velocity
	easeInSine: function (t) { return -1*Math.cos(t*(Math.PI/2))+1 },
	// decelerating to zero velocity
	easeOutSine: function (t) { return 1*Math.sin(t*(Math.PI/2)) },
	// accelerating until halfway, then decelerating
	easeInOutSine: function (t) { return -0.5*(Math.cos(Math.PI*t)-1) },
	
	// accelerating from zero velocity
	easeInExpo: function (t) { return 1*Math.pow(2, 10*(t-1)) },
	// decelerating to zero velocity
	easeOutExpo: function (t) { return 1*(-Math.pow(2, -10*t)+1 ) },
	// accelerating until halfway, then decelerating
	easeInOutExpo: function (t) { t /= 0.5; if (t < 1) return 0.5 * Math.pow(2, 10*(t-1)); t--; return 0.5 * (-Math.pow(2, -10*t)+2); },
	
	// accelerating from zero velocity
	easeInCirc: function (t) { return -1*(Math.sqrt(1-t*t)-1) },
	// decelerating to zero velocity
	easeOutCirc: function (t) { t--; return 1*Math.sqrt(1-t*t); },
	// acceleration until halfway, then deceleration
	easeInOutCirc: function (t) { t /= 0.5; if(t<1) { return -0.5*(Math.sqrt(1-t*t)-1); }else{ t-=2; return 0.5*(Math.sqrt(1-t*t)+1); } }
};