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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")
}
})
*/
import { lerp } from 'app/utils'
const oktween = {}
let tweens = []
let last_t = 0
let id = 0
oktween.speed = 1
oktween.add = (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 = (fn) => { tween.after.push(fn); return tween }
tween.tick = 0
tween.skip = tween.skip || 1
tween.dt = 0
tweens.push(tween)
return tween
}
oktween.update = (t) => {
let done = false
requestAnimationFrame(oktween.update)
last_t = t * oktween.speed
if (tweens.length === 0) return
tweens.forEach((tween, i) => {
const dt = Math.min(1.0, (t - tween.start) / tween.duration)
tween.tick++
if (dt < 0 || (dt < 1 && (tween.tick % tween.skip != 0))) return
const ddt = tween.easing(dt)
tween.dt = ddt
tween.keys.forEach((prop) => {
let 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
})
if (tween.update) {
tween.update(tween.obj, dt)
}
if (dt === 1) {
if (tween.finished) {
tween.finished(tween)
}
if (tween.after.length) {
const 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 = true
tween.done = true
}
}
})
if (done) {
tweens = tweens.filter(tween => !tween.done)
}
}
requestAnimationFrame(oktween.update)
oktween.easing = {
linear: (t) => {
return t
},
circ_out: (t) => {
return Math.sqrt(1 - (t = t - 1) * t)
},
circ_in: (t) => {
return -(Math.sqrt(1 - (t * t)) - 1)
},
circ_in_out: (t) => {
return ((t*=2) < 1) ? -0.5 * (Math.sqrt(1 - t * t) - 1) : 0.5 * (Math.sqrt(1 - (t -= 2) * t) + 1)
},
quad_in: (n) => {
return Math.pow(n, 2)
},
quad_out: (n) => {
return n * (n - 2) * -1
},
quad_in_out: (n) => {
n = n * 2
if (n < 1) { return Math.pow(n, 2) / 2 }
return -1 * ((--n) * (n - 2) - 1) / 2
},
cubic_bezier: (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
let aGuessT = aX
for (let i = 0; i < 10; ++i) {
const currentSlope = GetSlope(aGuessT, mX1, mX2)
if (currentSlope == 0.0) return aGuessT
const 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)
}
}
}
export default oktween
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