phaser/src/geom/circle/Random.js

/**
 * @author       Richard Davey <rich@photonstorm.com>
 * @copyright    2019 Photon Storm Ltd.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */

var Point = require('../point/Point');

/**
 * Returns a uniformly distributed random point from anywhere within the given Circle.
 *
 * @function Phaser.Geom.Circle.Random
 * @since 3.0.0
 *
 * @generic {Phaser.Geom.Point} O - [out,$return]
 *
 * @param {Phaser.Geom.Circle} circle - The Circle to get a random point from.
 * @param {(Phaser.Geom.Point|object)} [out] - A Point or point-like object to set the random `x` and `y` values in.
 *
 * @return {(Phaser.Geom.Point|object)} A Point object with the random values set in the `x` and `y` properties.
 */
var Random = function (circle, out)
{
    if (out === undefined) { out = new Point(); }

    var t = 2 * Math.PI * Math.random();
    var u = Math.random() + Math.random();
    var r = (u > 1) ? 2 - u : u;
    var x = r * Math.cos(t);
    var y = r * Math.sin(t);

    out.x = circle.x + (x * circle.radius);
    out.y = circle.y + (y * circle.radius);

    return out;
};

module.exports = Random;