react-native/Libraries/Animated/SpringConfig.js

103 lines
2.4 KiB
JavaScript

/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule SpringConfig
* @flow
*/
'use strict';
type SpringConfigType = {
tension: number,
friction: number,
};
function tensionFromOrigamiValue(oValue) {
return (oValue - 30) * 3.62 + 194;
}
function frictionFromOrigamiValue(oValue) {
return (oValue - 8) * 3 + 25;
}
function fromOrigamiTensionAndFriction(
tension: number,
friction: number,
): SpringConfigType {
return {
tension: tensionFromOrigamiValue(tension),
friction: frictionFromOrigamiValue(friction)
};
}
function fromBouncinessAndSpeed(
bounciness: number,
speed: number,
): SpringConfigType {
function normalize(value, startValue, endValue) {
return (value - startValue) / (endValue - startValue);
}
function projectNormal(n, start, end) {
return start + (n * (end - start));
}
function linearInterpolation(t, start, end) {
return t * end + (1 - t) * start;
}
function quadraticOutInterpolation(t, start, end) {
return linearInterpolation(2 * t - t * t, start, end);
}
function b3Friction1(x) {
return (0.0007 * Math.pow(x, 3)) -
(0.031 * Math.pow(x, 2)) + 0.64 * x + 1.28;
}
function b3Friction2(x) {
return (0.000044 * Math.pow(x, 3)) -
(0.006 * Math.pow(x, 2)) + 0.36 * x + 2;
}
function b3Friction3(x) {
return (0.00000045 * Math.pow(x, 3)) -
(0.000332 * Math.pow(x, 2)) + 0.1078 * x + 5.84;
}
function b3Nobounce(tension) {
if (tension <= 18) {
return b3Friction1(tension);
} else if (tension > 18 && tension <= 44) {
return b3Friction2(tension);
} else {
return b3Friction3(tension);
}
}
var b = normalize(bounciness / 1.7, 0, 20);
b = projectNormal(b, 0, 0.8);
var s = normalize(speed / 1.7, 0, 20);
var bouncyTension = projectNormal(s, 0.5, 200);
var bouncyFriction = quadraticOutInterpolation(
b,
b3Nobounce(bouncyTension),
0.01
);
return {
tension: tensionFromOrigamiValue(bouncyTension),
friction: frictionFromOrigamiValue(bouncyFriction)
};
}
module.exports = {
fromOrigamiTensionAndFriction,
fromBouncinessAndSpeed,
};