# Source: src/physics/Physics.js

    /**
    * @author       Richard Davey <rich@photonstorm.com>
    * @copyright    2016 Photon Storm Ltd.
    * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
    */

    /**
    * The Physics Manager is responsible for looking after all of the running physics systems.
    * Phaser supports 4 physics systems: Arcade Physics, P2, Ninja Physics and Box2D via a commercial plugin.
    *
    * Game Objects (such as Sprites) can only belong to 1 physics system, but you can have multiple systems active in a single game.
    *
    * For example you could have P2 managing a polygon-built terrain landscape that an vehicle drives over, while it could be firing bullets that use the
    * faster (due to being much simpler) Arcade Physics system.
    *
    * @class Phaser.Physics
    * @constructor
    * @param {Phaser.Game} game - A reference to the currently running game.
    * @param {object} [physicsConfig=null] - A physics configuration object to pass to the Physics world on creation.
    */
    Phaser.Physics = function (game, config) {

        config = config || {};

        /**
        * @property {Phaser.Game} game - Local reference to game.
        */
        this.game = game;

        /**
        * @property {object} config - The physics configuration object as passed to the game on creation.
        */
        this.config = config;

        /**
        * @property {Phaser.Physics.Arcade} arcade - The Arcade Physics system.
        */
        this.arcade = null;

        /**
        * @property {Phaser.Physics.P2} p2 - The P2.JS Physics system.
        */
        this.p2 = null;

        /**
        * @property {Phaser.Physics.Ninja} ninja - The N+ Ninja Physics system.
        */
        this.ninja = null;

        /**
        * @property {Phaser.Physics.Box2D} box2d - The Box2D Physics system.
        */
        this.box2d = null;

        /**
        * @property {Phaser.Physics.Chipmunk} chipmunk - The Chipmunk Physics system (to be done).
        */
        this.chipmunk = null;

        /**
        * @property {Phaser.Physics.Matter} matter - The MatterJS Physics system (coming soon).
        */
        this.matter = null;

        this.parseConfig();

    };

    /**
    * @const
    * @type {number}
    */
    Phaser.Physics.ARCADE = 0;

    /**
    * @const
    * @type {number}
    */
    Phaser.Physics.P2JS = 1;

    /**
    * @const
    * @type {number}
    */
    Phaser.Physics.NINJA = 2;

    /**
    * @const
    * @type {number}
    */
    Phaser.Physics.BOX2D = 3;

    /**
    * @const
    * @type {number}
    */
    Phaser.Physics.CHIPMUNK = 4;

    /**
    * @const
    * @type {number}
    */
    Phaser.Physics.MATTERJS = 5;

    Phaser.Physics.prototype = {

        /**
        * Parses the Physics Configuration object passed to the Game constructor and starts any physics systems specified within.
        *
        * @method Phaser.Physics#parseConfig
        */
        parseConfig: function () {

            if ((!this.config.hasOwnProperty('arcade') || this.config['arcade'] === true) && Phaser.Physics.hasOwnProperty('Arcade'))
            {
                //  If Arcade isn't specified, we create it automatically if we can
                this.arcade = new Phaser.Physics.Arcade(this.game);
            }

            if (this.config.hasOwnProperty('ninja') && this.config['ninja'] === true && Phaser.Physics.hasOwnProperty('Ninja'))
            {
                this.ninja = new Phaser.Physics.Ninja(this.game);
            }

            if (this.config.hasOwnProperty('p2') && this.config['p2'] === true && Phaser.Physics.hasOwnProperty('P2'))
            {
                this.p2 = new Phaser.Physics.P2(this.game, this.config);
            }

            if (this.config.hasOwnProperty('box2d') && this.config['box2d'] === true && Phaser.Physics.hasOwnProperty('BOX2D'))
            {
                this.box2d = new Phaser.Physics.BOX2D(this.game, this.config);
            }

            if (this.config.hasOwnProperty('matter') && this.config['matter'] === true && Phaser.Physics.hasOwnProperty('Matter'))
            {
                this.matter = new Phaser.Physics.Matter(this.game, this.config);
            }

        },

        /**
        * This will create an instance of the requested physics simulation.
        * Phaser.Physics.Arcade is running by default, but all others need activating directly.
        *
        * You can start the following physics systems:
        *
        * Phaser.Physics.P2JS - A full-body advanced physics system by Stefan Hedman.
        * Phaser.Physics.NINJA - A port of Metanet Softwares N+ physics system.
        * Phaser.Physics.BOX2D - A commercial Phaser Plugin (see http://phaser.io)
        *
        * Both Ninja Physics and Box2D require their respective plugins to be loaded before you can start them.
        * They are not bundled into the core Phaser library.
        *
        * If the physics world has already been created (i.e. in another state in your game) then
        * calling startSystem will reset the physics world, not re-create it. If you need to start them again from their constructors
        * then set Phaser.Physics.p2 (or whichever system you want to recreate) to `null` before calling `startSystem`.
        *
        * @method Phaser.Physics#startSystem
        * @param {number} system - The physics system to start: Phaser.Physics.ARCADE, Phaser.Physics.P2JS, Phaser.Physics.NINJA or Phaser.Physics.BOX2D.
        */
        startSystem: function (system) {

            if (system === Phaser.Physics.ARCADE)
            {
                this.arcade = new Phaser.Physics.Arcade(this.game);
            }
            else if (system === Phaser.Physics.P2JS)
            {
                if (this.p2 === null)
                {
                    this.p2 = new Phaser.Physics.P2(this.game, this.config);
                }
                else
                {
                    this.p2.reset();
                }
            }
            else if (system === Phaser.Physics.NINJA)
            {
                this.ninja = new Phaser.Physics.Ninja(this.game);
            }
            else if (system === Phaser.Physics.BOX2D)
            {
                if (this.box2d === null)
                {
                    this.box2d = new Phaser.Physics.Box2D(this.game, this.config);
                }
                else
                {
                    this.box2d.reset();
                }
            }
            else if (system === Phaser.Physics.MATTERJS)
            {
                if (this.matter === null)
                {
                    this.matter = new Phaser.Physics.Matter(this.game, this.config);
                }
                else
                {
                    this.matter.reset();
                }
            }

        },

        /**
        * This will create a default physics body on the given game object or array of objects.
        * A game object can only have 1 physics body active at any one time, and it can't be changed until the object is destroyed.
        * It can be for any of the physics systems that have been started:
        *
        * Phaser.Physics.Arcade - A light weight AABB based collision system with basic separation.
        * Phaser.Physics.P2JS - A full-body advanced physics system supporting multiple object shapes, polygon loading, contact materials, springs and constraints.
        * Phaser.Physics.NINJA - A port of Metanet Softwares N+ physics system. Advanced AABB and Circle vs. Tile collision.
        * Phaser.Physics.BOX2D - A port of https://code.google.com/p/box2d-html5
        * Phaser.Physics.MATTER - A full-body and light-weight advanced physics system (still in development)
        * Phaser.Physics.CHIPMUNK is still in development.
        *
        * If you require more control over what type of body is created, for example to create a Ninja Physics Circle instead of the default AABB, then see the
        * individual physics systems `enable` methods instead of using this generic one.
        *
        * @method Phaser.Physics#enable
        * @param {object|array} object - The game object to create the physics body on. Can also be an array of objects, a body will be created on every object in the array.
        * @param {number} [system=Phaser.Physics.ARCADE] - The physics system that will be used to create the body. Defaults to Arcade Physics.
        * @param {boolean} [debug=false] - Enable the debug drawing for this body. Defaults to false.
        */
        enable: function (object, system, debug) {

            if (system === undefined) { system = Phaser.Physics.ARCADE; }
            if (debug === undefined) { debug = false; }

            if (system === Phaser.Physics.ARCADE)
            {
                this.arcade.enable(object);
            }
            else if (system === Phaser.Physics.P2JS && this.p2)
            {
                this.p2.enable(object, debug);
            }
            else if (system === Phaser.Physics.NINJA && this.ninja)
            {
                this.ninja.enableAABB(object);
            }
            else if (system === Phaser.Physics.BOX2D && this.box2d)
            {
                this.box2d.enable(object);
            }
            else if (system === Phaser.Physics.MATTERJS && this.matter)
            {
                this.matter.enable(object);
            }
            else
            {
                console.warn(object.key + ' is attempting to enable a physics body using an unknown physics system.');
            }

        },

        /**
        * preUpdate checks.
        *
        * @method Phaser.Physics#preUpdate
        * @protected
        */
        preUpdate: function () {

            //  ArcadePhysics / Ninja don't have a core to preUpdate

            if (this.p2)
            {
                this.p2.preUpdate();
            }

            if (this.box2d)
            {
                this.box2d.preUpdate();
            }

            if (this.matter)
            {
                this.matter.preUpdate();
            }

        },

        /**
        * Updates all running physics systems.
        *
        * @method Phaser.Physics#update
        * @protected
        */
        update: function () {

            //  ArcadePhysics / Ninja don't have a core to update

            if (this.p2)
            {
                this.p2.update();
            }

            if (this.box2d)
            {
                this.box2d.update();
            }

            if (this.matter)
            {
                this.matter.update();
            }

        },

        /**
        * Updates the physics bounds to match the world dimensions.
        *
        * @method Phaser.Physics#setBoundsToWorld
        * @protected
        */
        setBoundsToWorld: function () {

            if (this.arcade)
            {
                this.arcade.setBoundsToWorld();
            }

            if (this.ninja)
            {
                this.ninja.setBoundsToWorld();
            }

            if (this.p2)
            {
                this.p2.setBoundsToWorld();
            }

            if (this.box2d)
            {
                this.box2d.setBoundsToWorld();
            }

            if (this.matter)
            {
                this.matter.setBoundsToWorld();
            }

        },

        /**
        * Clears down all active physics systems. This doesn't destroy them, it just clears them of objects and is called when the State changes.
        *
        * @method Phaser.Physics#clear
        * @protected
        */
        clear: function () {

            if (this.p2)
            {
                this.p2.clear();
            }

            if (this.box2d)
            {
                this.box2d.clear();
            }

            if (this.matter)
            {
                this.matter.clear();
            }

        },

        /**
        * Resets the active physics system. Called automatically on a Phaser.State swap.
        *
        * @method Phaser.Physics#reset
        * @protected
        */
        reset: function () {

            if (this.p2)
            {
                this.p2.reset();
            }

            if (this.box2d)
            {
                this.box2d.reset();
            }

            if (this.matter)
            {
                this.matter.reset();
            }

        },

        /**
        * Destroys all active physics systems. Usually only called on a Game Shutdown, not on a State swap.
        *
        * @method Phaser.Physics#destroy
        */
        destroy: function () {

            if (this.p2)
            {
                this.p2.destroy();
            }

            if (this.box2d)
            {
                this.box2d.destroy();
            }

            if (this.matter)
            {
                this.matter.destroy();
            }

            this.arcade = null;
            this.ninja = null;
            this.p2 = null;
            this.box2d = null;
            this.matter = null;

        }

    };

    Phaser.Physics.prototype.constructor = Phaser.Physics;