arcade-physics/lib/math/easing/elastic/InOut.js

Use Arcade Physics without Phaser.

"use strict";
/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2020 Photon Storm Ltd.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */
Object.defineProperty(exports, "__esModule", { value: true });
/**
 * Elastic ease-in/out.
 *
 * @function Phaser.Math.Easing.Elastic.InOut
 * @since 3.0.0
 *
 * @param {number} v - The value to be tweened.
 * @param {number} [amplitude=0.1] - The amplitude of the elastic ease.
 * @param {number} [period=0.1] - Sets how tight the sine-wave is, where smaller values are tighter waves, which result in more cycles.
 *
 * @return {number} The tweened value.
 */
const InOut = (v, amplitude, period) => {
    if (amplitude === undefined) {
        amplitude = 0.1;
    }
    if (period === undefined) {
        period = 0.1;
    }
    if (v === 0) {
        return 0;
    }
    else if (v === 1) {
        return 1;
    }
    else {
        let s = period / 4;
        if (amplitude < 1) {
            amplitude = 1;
        }
        else {
            s = (period * Math.asin(1 / amplitude)) / (2 * Math.PI);
        }
        if ((v *= 2) < 1) {
            return -0.5 * (amplitude * Math.pow(2, 10 * (v -= 1)) * Math.sin(((v - s) * (2 * Math.PI)) / period));
        }
        else {
            return amplitude * Math.pow(2, -10 * (v -= 1)) * Math.sin(((v - s) * (2 * Math.PI)) / period) * 0.5 + 1;
        }
    }
};
exports.default = InOut;
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