phaser/src/geom/line/ReflectAngle.js

A fast, free and fun HTML5 Game Framework for Desktop and Mobile web browsers from the team at Phaser Studio Inc.

/**
 * @author       Richard Davey <rich@phaser.io>
 * @copyright    2013-2026 Phaser Studio Inc.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */

var Angle = require('./Angle');
var NormalAngle = require('./NormalAngle');

/**
 * Calculates the reflected angle of Line A off the surface represented by Line B. This is the outgoing angle based on the angle of incidence (Line A) and the surface normal of Line B. The result is in radians.
 *
 * @function Phaser.Geom.Line.ReflectAngle
 * @since 3.0.0
 *
 * @param {Phaser.Geom.Line} lineA - The incident line whose angle of incidence is used.
 * @param {Phaser.Geom.Line} lineB - The surface line, used to calculate the normal angle of reflection.
 *
 * @return {number} The reflected angle of Line A off the surface of Line B, in radians.
 */
var ReflectAngle = function (lineA, lineB)
{
    return (2 * NormalAngle(lineB) - Math.PI - Angle(lineA));
};

module.exports = ReflectAngle;