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/*
oktween.add({
obj: el.style,
units: "px",
from: { left: 0 },
to: { left: 100 },
duration: 1000,
easing: oktween.easing.circ_out,
update: function(obj){
console.log(obj.left)
}
finished: function(){
console.log("done")
}
})
*/
var oktween = (function(){
var oktween = {}
var tweens = oktween.tweens = []
var last_t = 0
var id = 0
oktween.speed = 1
oktween.raf = requestAnimationFrame
oktween.add = function(tween){
tween.id = id++
tween.obj = tween.obj || {}
if (tween.easing) {
if (typeof tween.easing == "string") {
tween.easing = oktween.easing[tween.easing]
}
}
else {
tween.easing = oktween.easing.linear
}
if (! ('from' in tween) && ! ('to' in tween)) {
tween.keys = []
}
else if (! ('from' in tween) ) {
tween.from = {}
tween.keys = Object.keys(tween.to)
tween.keys.forEach(function(prop){
tween.from[prop] = parseFloat(tween.obj[prop])
})
}
else {
tween.keys = Object.keys(tween.from)
}
tween.delay = tween.delay || 0
tween.start = last_t + tween.delay
tween.done = false
tween.after = tween.after || []
tween.then = function(fn){ tween.after.push(fn); return tween }
tween.cancel = function(){
var index = tweens.indexOf(tween)
if (index != -1) tweens.splice(index, 1)
tween.obj = null
tween.after = null
tween.done = null
}
tween.tick = 0
tween.skip = tween.skip || 1
tween.dt = 0
tweens.push(tween)
return tween
}
oktween.update = function(t) {
oktween.raf(oktween.update)
last_t = t * oktween.speed
if (tweens.length == 0) return
var done = false
tweens.forEach(function(tween, i){
var dt = Math.min(1.0, (t - tween.start) / tween.duration)
tween.tick++
if (dt < 0 || (dt < 1 && (tween.tick % tween.skip != 0))) return
var ddt = tween.dt = tween.easing(dt)
tween.keys.forEach(function(prop){
val = lerp( ddt, tween.from[prop], tween.to[prop] )
if (tween.round) val = Math.round(val)
if (tween.units) val = (Math.round(val)) + tween.units
tween.obj[prop] = val
})
tween.update && tween.update(tween.obj, dt)
if (dt == 1) {
tween.finished && tween.finished(tween)
if (tween.after.length) {
var twn = tween.after.shift()
twn.obj = twn.obj || tween.obj
twn.after = tween.after
oktween.add(twn)
}
if (tween.loop) {
tween.start = t + tween.delay
}
else {
done = tween.done = true
}
}
})
if (done) {
tweens = tweens.filter(function(tween){ return ! tween.done })
}
}
function lerp(n,a,b){ return (b-a)*n+a }
// requestAnimationFrame(oktween.update)
oktween.easing = {
linear: function(t){
return t
},
circ_out: function(t) {
return Math.sqrt(1 - (t = t - 1) * t)
},
circ_in: function(t){
return -(Math.sqrt(1 - (t * t)) - 1)
},
circ_in_out: function(t) {
return ((t*=2) < 1) ? -0.5 * (Math.sqrt(1 - t * t) - 1) : 0.5 * (Math.sqrt(1 - (t -= 2) * t) + 1)
},
quad_in: function(n){
return Math.pow(n, 2)
},
quad_out: function(n){
return n * (n - 2) * -1
},
quad_in_out: function(n){
n = n * 2
if(n < 1){ return Math.pow(n, 2) / 2 }
return -1 * ((--n) * (n - 2) - 1) / 2
},
cubic_bezier: function (mX1, mY1, mX2, mY2) {
function A(aA1, aA2) { return 1.0 - 3.0 * aA2 + 3.0 * aA1; }
function B(aA1, aA2) { return 3.0 * aA2 - 6.0 * aA1; }
function C(aA1) { return 3.0 * aA1; }
// Returns x(t) given t, x1, and x2, or y(t) given t, y1, and y2.
function CalcBezier(aT, aA1, aA2) {
return ((A(aA1, aA2)*aT + B(aA1, aA2))*aT + C(aA1))*aT;
}
// Returns dx/dt given t, x1, and x2, or dy/dt given t, y1, and y2.
function GetSlope(aT, aA1, aA2) {
return 3.0 * A(aA1, aA2)*aT*aT + 2.0 * B(aA1, aA2) * aT + C(aA1);
}
function GetTForX(aX) {
// Newton raphson iteration
var aGuessT = aX;
for (var i = 0; i < 10; ++i) {
var currentSlope = GetSlope(aGuessT, mX1, mX2);
if (currentSlope == 0.0) return aGuessT;
var currentX = CalcBezier(aGuessT, mX1, mX2) - aX;
aGuessT -= currentX / currentSlope;
}
return aGuessT;
}
return function(aX) {
if (mX1 == mY1 && mX2 == mY2) return aX; // linear
return CalcBezier(aX, mY1, mY2);
}
}
}
return oktween
})()
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