Created
March 24, 2017 13:05
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Tween.js ES6 easing functions
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| // k = progress between 0 and 1 | |
| const easing = { | |
| quadratic: { | |
| in(k) { | |
| return k * k; | |
| }, | |
| out(k) { | |
| return k * (2 - k); | |
| }, | |
| inOut(k) { | |
| if ((k *= 2) < 1) | |
| return 0.5 * k * k; | |
| return - 0.5 * (--k * (k - 2) - 1); | |
| } | |
| }, | |
| cubic: { | |
| in(k) { | |
| return k * k * k; | |
| }, | |
| out(k) { | |
| return --k * k * k + 1; | |
| }, | |
| inOut(k) { | |
| if ((k *= 2) < 1) | |
| return 0.5 * k * k * k; | |
| return 0.5 * ((k -= 2) * k * k + 2); | |
| } | |
| }, | |
| quartic: { | |
| in(k) { | |
| return k * k * k * k; | |
| }, | |
| out(k) { | |
| return 1 - (--k * k * k * k); | |
| }, | |
| inOut(k) { | |
| if ((k *= 2) < 1) | |
| return 0.5 * k * k * k * k; | |
| return - 0.5 * ((k -= 2) * k * k * k - 2); | |
| } | |
| }, | |
| quintic: { | |
| in(k) { | |
| return k * k * k * k * k; | |
| }, | |
| out(k) { | |
| return --k * k * k * k * k + 1; | |
| }, | |
| inOut(k) { | |
| if ((k *= 2) < 1) | |
| return 0.5 * k * k * k * k * k; | |
| return 0.5 * ((k -= 2) * k * k * k * k + 2); | |
| } | |
| }, | |
| exponential: { | |
| in(k) { | |
| return k === 0 ? 0 : Math.pow(1024, k - 1); | |
| }, | |
| out(k) { | |
| return k === 1 ? 1 : 1 - Math.pow(2, - 10 * k); | |
| }, | |
| inOut(k) { | |
| if (k === 0) | |
| return 0; | |
| if (k === 1) | |
| return 1; | |
| if ((k *= 2) < 1) | |
| return 0.5 * Math.pow(1024, k - 1); | |
| return 0.5 * (- Math.pow(2, - 10 * (k - 1)) + 2); | |
| } | |
| }, | |
| circular: { | |
| in(k) { | |
| return 1 - Math.sqrt(1 - k * k); | |
| }, | |
| out(k) { | |
| return Math.sqrt(1 - (--k * k)); | |
| }, | |
| inOut(k) { | |
| if ((k *= 2) < 1) | |
| return - 0.5 * (Math.sqrt(1 - k * k) - 1); | |
| return 0.5 * (Math.sqrt(1 - (k -= 2) * k) + 1); | |
| } | |
| }, | |
| elastic: { | |
| in(k) { | |
| if (k === 0) | |
| return 0; | |
| if (k === 1) | |
| return 1; | |
| return -Math.pow(2, 10 * (k - 1)) * Math.sin((k - 1.1) * 5 * Math.PI); | |
| }, | |
| out(k) { | |
| if (k === 0) | |
| return 0; | |
| if (k === 1) | |
| return 1; | |
| return Math.pow(2, -10 * k) * Math.sin((k - 0.1) * 5 * Math.PI) + 1; | |
| }, | |
| inOut(k) { | |
| if (k === 0) | |
| return 0; | |
| if (k === 1) | |
| return 1; | |
| k *= 2; | |
| if (k < 1) | |
| return -0.5 * Math.pow(2, 10 * (k - 1)) * Math.sin((k - 1.1) * 5 * Math.PI); | |
| return 0.5 * Math.pow(2, -10 * (k - 1)) * Math.sin((k - 1.1) * 5 * Math.PI) + 1; | |
| } | |
| }, | |
| back: { | |
| in(k) { | |
| const s = 1.70158; | |
| return k * k * ((s + 1) * k - s); | |
| }, | |
| out(k) { | |
| const s = 1.70158; | |
| return --k * k * ((s + 1) * k + s) + 1; | |
| }, | |
| inOut(k) { | |
| const s = 1.70158 * 1.525; | |
| if ((k *= 2) < 1) | |
| return 0.5 * (k * k * ((s + 1) * k - s)); | |
| return 0.5 * ((k -= 2) * k * ((s + 1) * k + s) + 2); | |
| } | |
| }, | |
| bounce: { | |
| in(k) { | |
| return 1 - easing.bounce.out(1 - k); | |
| }, | |
| out(k) { | |
| if (k < (1 / 2.75)) { | |
| return 7.5625 * k * k; | |
| } else if (k < (2 / 2.75)) { | |
| return 7.5625 * (k -= (1.5 / 2.75)) * k + 0.75; | |
| } else if (k < (2.5 / 2.75)) { | |
| return 7.5625 * (k -= (2.25 / 2.75)) * k + 0.9375; | |
| } else { | |
| return 7.5625 * (k -= (2.625 / 2.75)) * k + 0.984375; | |
| } | |
| }, | |
| inOut(k) { | |
| if (k < 0.5) | |
| return easing.bounce.in(k * 2) * 0.5; | |
| return easing.bounce.out(k * 2 - 1) * 0.5 + 0.5; | |
| } | |
| } | |
| }; |
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