99 lines
2.3 KiB
JavaScript
99 lines
2.3 KiB
JavaScript
/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @format
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* @flow strict
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*/
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'use strict';
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type SpringConfigType = {
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stiffness: number,
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damping: number,
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...
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};
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function stiffnessFromOrigamiValue(oValue: number) {
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return (oValue - 30) * 3.62 + 194;
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}
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function dampingFromOrigamiValue(oValue: number) {
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return (oValue - 8) * 3 + 25;
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}
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export function fromOrigamiTensionAndFriction(
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tension: number,
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friction: number,
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): SpringConfigType {
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return {
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stiffness: stiffnessFromOrigamiValue(tension),
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damping: dampingFromOrigamiValue(friction),
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};
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}
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export function fromBouncinessAndSpeed(
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bounciness: number,
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speed: number,
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): SpringConfigType {
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function normalize(value: number, startValue: number, endValue: number) {
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return (value - startValue) / (endValue - startValue);
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}
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function projectNormal(n: number, start: number, end: number) {
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return start + n * (end - start);
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}
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function linearInterpolation(t: number, start: number, end: number) {
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return t * end + (1 - t) * start;
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}
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function quadraticOutInterpolation(t: number, start: number, end: number) {
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return linearInterpolation(2 * t - t * t, start, end);
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}
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function b3Friction1(x: number) {
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return 0.0007 * Math.pow(x, 3) - 0.031 * Math.pow(x, 2) + 0.64 * x + 1.28;
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}
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function b3Friction2(x: number) {
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return 0.000044 * Math.pow(x, 3) - 0.006 * Math.pow(x, 2) + 0.36 * x + 2;
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}
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function b3Friction3(x: number) {
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return (
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0.00000045 * Math.pow(x, 3) -
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0.000332 * Math.pow(x, 2) +
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0.1078 * x +
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5.84
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);
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}
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function b3Nobounce(tension: number) {
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if (tension <= 18) {
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return b3Friction1(tension);
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} else if (tension > 18 && tension <= 44) {
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return b3Friction2(tension);
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} else {
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return b3Friction3(tension);
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}
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}
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let b = normalize(bounciness / 1.7, 0, 20);
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b = projectNormal(b, 0, 0.8);
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const s = normalize(speed / 1.7, 0, 20);
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const bouncyTension = projectNormal(s, 0.5, 200);
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const bouncyFriction = quadraticOutInterpolation(
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b,
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b3Nobounce(bouncyTension),
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0.01,
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);
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return {
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stiffness: stiffnessFromOrigamiValue(bouncyTension),
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damping: dampingFromOrigamiValue(bouncyFriction),
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};
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}
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