// See: http://www.actionscript.org/forums/showthread.php3?s=&threadid=5312

// simple linear tweening - no acceleration
// t: current time, b: beginning value, c: change in value, d: duration
Math.linearTween = function (t, b, c, d) {
	return c*t/d + b;
}

 ///////////// QUADRATIC EASING ////////////////////////
//// Robert Penner - Sept. 2001 - robertpenner.com ////

// quadratic easing in - accelerating from zero velocity
// t: current time, b: beginning value, c: change in value, d: duration
// t and d can be frames or seconds/milliseconds
Math.easeInQuad = function (t, b, c, d) {
	return c*t*t/(d*d) + b;
}

// quadratic easing out - decelerating to zero velocity
Math.easeOutQuad = function (t, b, c, d) {
	return -c*t*t/(d*d) + 2*c*t/d + b;
}

// quadratic easing in/out - acceleration until halfway, then deceleration
Math.easeInOutQuad = function (t, b, c, d) {
	if (t < d/2) return 2*c*t*t/(d*d) + b;
	var ts = t - d/2;
	return -2*c*ts*ts/(d*d) + 2*c*ts/d + c/2 + b;
}

 ///////////// SINUSOIDAL EASING ///////////////////////
//// Robert Penner - Sept. 2001 - robertpenner.com ////

// sinusoidal easing in - accelerating from zero velocity
// t: current time, b: beginning value, c: change in position, d: duration
Math.easeInSine = function (t, b, c, d) {
	return -c * Math.cos(t/d * Math.PI/2) + c + b;
}

// sinusoidal easing out - decelerating to zero velocity
// t: current time, b: beginning value, c: change in position, d: duration
Math.easeOutSine = function (t, b, c, d) {
	return c * Math.sin(t/d * Math.PI/2) + b;
}

// sinusoidal easing in/out - accelerating until halfway, then decelerating
// t: current time, b: beginning value, c: change in position, d: duration
Math.easeInOutSine = function (t, b, c, d) {
	return -c/2 * (Math.cos(Math.PI*t/d) - 1) + b;
}

///////////// EXPONENTIAL EASING ////////////////////// 
//// Robert Penner - Sept. 2001 - robertpenner.com //// 

// exponential easing in - accelerating from zero velocity
// t: current time, b: beginning value, c: change in position, d: duration
Math.easeInExpo = function (t, b, c, d) {
	var flip = 1;
	if (c < 0) {
		flip *= -1;
		c *= -1;
	}
	return flip * (Math.exp(Math.log(c)/d * t)) + b;
}

// exponential easing out - decelerating to zero velocity
// t: current time, b: beginning value, c: change in position, d: duration
Math.easeOutExpo = function (t, b, c, d) {
	var flip = 1;
	if (c < 0) {
		flip *= -1;
		c *= -1;
	}
	return flip * (-Math.exp(-Math.log(c)/d * (t-d)) + c + 1) + b;
}

// exponential easing in/out - accelerating until halfway, then decelerating
// t: current time, b: beginning value, c: change in position, d: duration
Math.easeInOutExpo = function (t, b, c, d) {
	var flip = 1;
	if (c < 0) {
		flip *= -1;
		c *= -1;
	}
	if (t < d/2) return flip * (Math.exp(Math.log(c/2)/(d/2) * t)) + b;
	return flip * (-Math.exp(-2*Math.log(c/2)/d * (t-d)) + c + 1) + b;
}