2018-02-12 16:01:20 +00:00
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/**
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* @author Richard Davey <rich@photonstorm.com>
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* @copyright 2018 Photon Storm Ltd.
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* @license {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
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*/
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2017-10-06 03:52:41 +00:00
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/**
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2018-05-24 17:48:12 +00:00
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* Calculate a smooth interpolation percentage of `x` between `min` and `max`.
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2018-05-24 17:11:18 +00:00
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*
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2018-05-24 16:03:42 +00:00
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* The function receives the number `x` as an argument and returns 0 if `x` is less than or equal to the left edge,
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* 1 if `x` is greater than or equal to the right edge, and smoothly interpolates, using a Hermite polynomial,
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* between 0 and 1 otherwise.
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2018-05-23 09:46:16 +00:00
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*
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2017-10-06 03:52:41 +00:00
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* @function Phaser.Math.SmoothStep
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* @since 3.0.0
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2018-05-24 17:11:18 +00:00
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* @see {@link https://en.wikipedia.org/wiki/Smoothstep}
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2017-10-06 03:52:41 +00:00
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*
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2018-05-24 16:03:42 +00:00
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* @param {number} x - The input value.
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* @param {number} min - The minimum value, also known as the 'left edge', assumed smaller than the 'right edge'.
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* @param {number} max - The maximum value, also known as the 'right edge', assumed greater than the 'left edge'.
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2017-10-06 03:52:41 +00:00
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*
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2018-05-24 17:48:12 +00:00
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* @return {number} The percentage of interpolation, between 0 and 1.
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2017-10-06 03:52:41 +00:00
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*/
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2016-12-07 17:16:59 +00:00
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var SmoothStep = function (x, min, max)
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{
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2018-05-24 16:03:42 +00:00
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if (x <= min)
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{
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return 0;
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}
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2016-12-07 17:16:59 +00:00
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2018-05-24 16:03:42 +00:00
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if (x >= max)
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{
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return 1;
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}
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x = (x - min) / (max - min);
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2018-05-24 17:11:18 +00:00
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return x * x * (3 - 2 * x);
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2016-12-07 17:16:59 +00:00
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};
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module.exports = SmoothStep;
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