103 lines
2.4 KiB
JavaScript
103 lines
2.4 KiB
JavaScript
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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* All rights reserved.
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*
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* This source code is licensed under the BSD-style license found in the
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* LICENSE file in the root directory of this source tree. An additional grant
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* of patent rights can be found in the PATENTS file in the same directory.
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*
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* @providesModule SpringConfig
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* @flow
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*/
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'use strict';
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type SpringConfigType = {
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tension: number,
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friction: number,
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};
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function tensionFromOrigamiValue(oValue) {
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return (oValue - 30) * 3.62 + 194;
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}
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function frictionFromOrigamiValue(oValue) {
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return (oValue - 8) * 3 + 25;
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}
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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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tension: tensionFromOrigamiValue(tension),
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friction: frictionFromOrigamiValue(friction)
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};
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}
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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, startValue, endValue) {
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return (value - startValue) / (endValue - startValue);
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}
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function projectNormal(n, start, end) {
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return start + (n * (end - start));
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}
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function linearInterpolation(t, start, end) {
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return t * end + (1 - t) * start;
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}
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function quadraticOutInterpolation(t, start, end) {
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return linearInterpolation(2 * t - t * t, start, end);
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}
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function b3Friction1(x) {
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return (0.0007 * Math.pow(x, 3)) -
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(0.031 * Math.pow(x, 2)) + 0.64 * x + 1.28;
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}
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function b3Friction2(x) {
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return (0.000044 * Math.pow(x, 3)) -
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(0.006 * Math.pow(x, 2)) + 0.36 * x + 2;
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}
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function b3Friction3(x) {
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return (0.00000045 * Math.pow(x, 3)) -
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(0.000332 * Math.pow(x, 2)) + 0.1078 * x + 5.84;
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}
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function b3Nobounce(tension) {
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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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var b = normalize(bounciness / 1.7, 0, 20);
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b = projectNormal(b, 0, 0.8);
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var s = normalize(speed / 1.7, 0, 20);
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var bouncyTension = projectNormal(s, 0.5, 200);
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var 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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tension: tensionFromOrigamiValue(bouncyTension),
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friction: frictionFromOrigamiValue(bouncyFriction)
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};
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}
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module.exports = {
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fromOrigamiTensionAndFriction,
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fromBouncinessAndSpeed,
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};
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