20 lines
703 B
JavaScript
20 lines
703 B
JavaScript
function decay({ velocity = 0, from = 0, power = 0.8, timeConstant = 350, restDelta = 0.5, modifyTarget, }) {
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const state = { done: false, value: from };
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let amplitude = power * velocity;
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const ideal = from + amplitude;
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const target = modifyTarget === undefined ? ideal : modifyTarget(ideal);
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if (target !== ideal)
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amplitude = target - from;
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return {
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next: (t) => {
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const delta = -amplitude * Math.exp(-t / timeConstant);
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state.done = !(delta > restDelta || delta < -restDelta);
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state.value = state.done ? target : target + delta;
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return state;
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},
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flipTarget: () => { },
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};
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}
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export { decay };
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