# Source: physics/arcade/Body.js

    /**
    * @author       Richard Davey <rich@photonstorm.com>
    * @copyright    2014 Photon Storm Ltd.
    * @license      {@link https://github.com/photonstorm/phaser/blob/master/license.txt|MIT License}
    */

    /**
    * The Physics Body is linked to a single Sprite. All physics operations should be performed against the body rather than
    * the Sprite itself. For example you can set the velocity, acceleration, bounce values etc all on the Body.
    *
    * @class Phaser.Physics.Arcade.Body
    * @classdesc Arcade Physics Body Constructor
    * @constructor
    * @param {Phaser.Sprite} sprite - The Sprite object this physics body belongs to.
    */
    Phaser.Physics.Arcade.Body = function (sprite) {

        /**
        * @property {Phaser.Sprite} sprite - Reference to the parent Sprite.
        */
        this.sprite = sprite;

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

        /**
        * @property {number} type - The type of physics system this body belongs to.
        */
        this.type = Phaser.Physics.ARCADE;

        /**
        * @property {Phaser.Point} offset - The offset of the Physics Body from the Sprite x/y position.
        */
        this.offset = new Phaser.Point();

        /**
        * @property {Phaser.Point} position - The position of the physics body.
        * @readonly
        */
        this.position = new Phaser.Point(sprite.x, sprite.y);

        /**
        * @property {Phaser.Point} prev - The previous position of the physics body.
        * @readonly
        */
        this.prev = new Phaser.Point(this.position.x, this.position.y);

        /**
        * @property {boolean} allowRotation - Allow this Body to be rotated? (via angularVelocity, etc)
        * @default
        */
        this.allowRotation = true;

        /**
        * @property {number} rotation - The amount the Body is rotated.
        */
        this.rotation = sprite.rotation;

        /**
        * @property {number} preRotation - The previous rotation of the physics body.
        * @readonly
        */
        this.preRotation = sprite.rotation;

        /**
        * @property {number} sourceWidth - The un-scaled original size.
        * @readonly
        */
        this.sourceWidth = sprite.texture.frame.width;

        /**
        * @property {number} sourceHeight - The un-scaled original size.
        * @readonly
        */
        this.sourceHeight = sprite.texture.frame.height;

        /**
        * @property {number} width - The calculated width of the physics body.
        */
        this.width = sprite.width;

        /**
        * @property .numInternal ID cache
        */
        this.height = sprite.height;

        /**
        * @property {number} halfWidth - The calculated width / 2 of the physics body.
        */
        this.halfWidth = Math.abs(sprite.width / 2);

        /**
        * @property {number} halfHeight - The calculated height / 2 of the physics body.
        */
        this.halfHeight = Math.abs(sprite.height / 2);

        /**
        * @property {Phaser.Point} center - The center coordinate of the Physics Body.
        */
        this.center = new Phaser.Point(sprite.x + this.halfWidth, sprite.y + this.halfHeight);

        /**
        * @property {Phaser.Point} velocity - The velocity in pixels per second sq. of the Body.
        */
        this.velocity = new Phaser.Point();

        /**
        * @property {Phaser.Point} newVelocity - New velocity.
        * @readonly
        */
        this.newVelocity = new Phaser.Point(0, 0);

        /**
        * @property {Phaser.Point} deltaMax - The Sprite position is updated based on the delta x/y values. You can set a cap on those (both +-) using deltaMax.
        */
        this.deltaMax = new Phaser.Point(0, 0);

        /**
        * @property {Phaser.Point} acceleration - The velocity in pixels per second sq. of the Body.
        */
        this.acceleration = new Phaser.Point();

        /**
        * @property {Phaser.Point} drag - The drag applied to the motion of the Body.
        */
        this.drag = new Phaser.Point();

        /**
        * @property {boolean} allowGravity - Allow this Body to be influenced by gravity? Either world or local.
        * @default
        */
        this.allowGravity = true;

        /**
        * @property {Phaser.Point} gravity - A local gravity applied to this Body. If non-zero this over rides any world gravity, unless Body.allowGravity is set to false.
        */
        this.gravity = new Phaser.Point(0, 0);

        /**
        * @property {Phaser.Point} bounce - The elasticitiy of the Body when colliding. bounce.x/y = 1 means full rebound, bounce.x/y = 0.5 means 50% rebound velocity.
        */
        this.bounce = new Phaser.Point();

        /**
        * @property {Phaser.Point} maxVelocity - The maximum velocity in pixels per second sq. that the Body can reach.
        * @default
        */
        this.maxVelocity = new Phaser.Point(10000, 10000);

        /**
        * @property {number} angularVelocity - The angular velocity in pixels per second sq. of the Body.
        * @default
        */
        this.angularVelocity = 0;

        /**
        * @property {number} angularAcceleration - The angular acceleration in pixels per second sq. of the Body.
        * @default
        */
        this.angularAcceleration = 0;

        /**
        * @property {number} angularDrag - The angular drag applied to the rotation of the Body.
        * @default
        */
        this.angularDrag = 0;

        /**
        * @property {number} maxAngular - The maximum angular velocity in pixels per second sq. that the Body can reach.
        * @default
        */
        this.maxAngular = 1000;

        /**
        * @property {number} mass - The mass of the Body.
        * @default
        */
        this.mass = 1;

        /**
        * @property {number} angle - The angle of the Body in radians as calculated by its velocity, rather than its visual angle.
        * @readonly
        */
        this.angle = 0;

        /**
        * @property {number} speed - The speed of the Body as calculated by its velocity.
        * @readonly
        */
        this.speed = 0;

        /**
        * @property {number} facing - A const reference to the direction the Body is traveling or facing.
        * @default
        */
        this.facing = Phaser.NONE;

        /**
        * @property {boolean} immovable - An immovable Body will not receive any impacts from other bodies.
        * @default
        */
        this.immovable = false;

        /**
        * If you have a Body that is being moved around the world via a tween or a Group motion, but its local x/y position never
        * actually changes, then you should set Body.moves = false. Otherwise it will most likely fly off the screen.
        * If you want the physics system to move the body around, then set moves to true.
        * @property {boolean} moves - Set to true to allow the Physics system to move this Body, other false to move it manually.
        * @default
        */
        this.moves = true;

        /**
        * This flag allows you to disable the custom x separation that takes place by Physics.Arcade.separate.
        * Used in combination with your own collision processHandler you can create whatever type of collision response you need.
        * @property {boolean} customSeparateX - Use a custom separation system or the built-in one?
        * @default
        */
        this.customSeparateX = false;

        /**
        * This flag allows you to disable the custom y separation that takes place by Physics.Arcade.separate.
        * Used in combination with your own collision processHandler you can create whatever type of collision response you need.
        * @property {boolean} customSeparateY - Use a custom separation system or the built-in one?
        * @default
        */
        this.customSeparateY = false;

        /**
        * When this body collides with another, the amount of overlap is stored here.
        * @property {number} overlapX - The amount of horizontal overlap during the collision.
        */
        this.overlapX = 0;

        /**
        * When this body collides with another, the amount of overlap is stored here.
        * @property {number} overlapY - The amount of vertical overlap during the collision.
        */
        this.overlapY = 0;

        /**
        * If a body is overlapping with another body, but neither of them are moving (maybe they spawned on-top of each other?) this is set to true.
        * @property {boolean} embedded - Body embed value.
        */
        this.embedded = false;

        /**
        * A Body can be set to collide against the World bounds automatically and rebound back into the World if this is set to true. Otherwise it will leave the World.
        * @property {boolean} collideWorldBounds - Should the Body collide with the World bounds?
        */
        this.collideWorldBounds = false;

        /**
        * Set the checkCollision properties to control which directions collision is processed for this Body.
        * For example checkCollision.up = false means it won't collide when the collision happened while moving up.
        * @property {object} checkCollision - An object containing allowed collision.
        */
        this.checkCollision = { none: false, any: true, up: true, down: true, left: true, right: true };

        /**
        * This object is populated with boolean values when the Body collides with another.
        * touching.up = true means the collision happened to the top of this Body for example.
        * @property {object} touching - An object containing touching results.
        */
        this.touching = { none: true, up: false, down: false, left: false, right: false };

        /**
        * This object is populated with previous touching values from the bodies previous collision.
        * @property {object} wasTouching - An object containing previous touching results.
        */
        this.wasTouching = { none: true, up: false, down: false, left: false, right: false };

        /**
        * This object is populated with boolean values when the Body collides with the World bounds or a Tile.
        * For example if blocked.up is true then the Body cannot move up.
        * @property {object} blocked - An object containing on which faces this Body is blocked from moving, if any.
        */
        this.blocked = { up: false, down: false, left: false, right: false };

        /**
        * If this is an especially small or fast moving object then it can sometimes skip over tilemap collisions if it moves through a tile in a step.
        * Set this padding value to add extra padding to its bounds. tilePadding.x applied to its width, y to its height.
        * @property {Phaser.Point} tilePadding - Extra padding to be added to this sprites dimensions when checking for tile collision.
        */
        this.tilePadding = new Phaser.Point();

        /**
        * @property {number} phaser - Is this Body in a preUpdate (1) or postUpdate (2) state?
        */
        this.phase = 0;

        /**
        * @property {boolean} _reset - Internal cache var.
        * @private
        */
        this._reset = true;

        /**
        * @property {number} _sx - Internal cache var.
        * @private
        */
        this._sx = sprite.scale.x;

        /**
        * @property {number} _sy - Internal cache var.
        * @private
        */
        this._sy = sprite.scale.y;

        /**
        * @property {number} _dx - Internal cache var.
        * @private
        */
        this._dx = 0;

        /**
        * @property {number} _dy - Internal cache var.
        * @private
        */
        this._dy = 0;

    };

    Phaser.Physics.Arcade.Body.prototype = {

        /**
        * Internal method.
        *
        * @method Phaser.Physics.Arcade.Body#updateBounds
        * @protected
        */
        updateBounds: function () {

            var asx = Math.abs(this.sprite.scale.x);
            var asy = Math.abs(this.sprite.scale.y);

            if (asx !== this._sx || asy !== this._sy)
            {
                this.width = this.sourceWidth * asx;
                this.height = this.sourceHeight * asy;
                this.halfWidth = Math.floor(this.width / 2);
                this.halfHeight = Math.floor(this.height / 2);
                this._sx = asx;
                this._sy = asy;
                this.center.setTo(this.position.x + this.halfWidth, this.position.y + this.halfHeight);

                this._reset = true;
            }

        },

        /**
        * Internal method.
        *
        * @method Phaser.Physics.Arcade.Body#preUpdate
        * @protected
        */
        preUpdate: function () {

            this.phase = 1;

            //  Store and reset collision flags
            this.wasTouching.none = this.touching.none;
            this.wasTouching.up = this.touching.up;
            this.wasTouching.down = this.touching.down;
            this.wasTouching.left = this.touching.left;
            this.wasTouching.right = this.touching.right;

            this.touching.none = true;
            this.touching.up = false;
            this.touching.down = false;
            this.touching.left = false;
            this.touching.right = false;

            this.blocked.up = false;
            this.blocked.down = false;
            this.blocked.left = false;
            this.blocked.right = false;

            this.embedded = false;

            this.updateBounds();

            this.position.x = (this.sprite.world.x - (this.sprite.anchor.x * this.width)) + this.offset.x;
            this.position.y = (this.sprite.world.y - (this.sprite.anchor.y * this.height)) + this.offset.y;
            this.rotation = this.sprite.angle;

            this.preRotation = this.rotation;

            if (this._reset || this.sprite._cache[4] === 1)
            {
                this.prev.x = this.position.x;
                this.prev.y = this.position.y;
            }

            if (this.moves)
            {
                this.game.physics.arcade.updateMotion(this);

                this.newVelocity.set(this.velocity.x * this.game.time.physicsElapsed, this.velocity.y * this.game.time.physicsElapsed);

                this.position.x += this.newVelocity.x;
                this.position.y += this.newVelocity.y;

                if (this.position.x !== this.prev.x || this.position.y !== this.prev.y)
                {
                    this.speed = Math.sqrt(this.velocity.x * this.velocity.x + this.velocity.y * this.velocity.y);
                    this.angle = Math.atan2(this.velocity.y, this.velocity.x);
                }

                //  Now the State update will throw collision checks at the Body
                //  And finally we'll integrate the new position back to the Sprite in postUpdate

                if (this.collideWorldBounds)
                {
                    this.checkWorldBounds();
                }
            }

            this._dx = this.deltaX();
            this._dy = this.deltaY();

            this._reset = false;

        },

        /**
        * Internal method.
        *
        * @method Phaser.Physics.Arcade.Body#postUpdate
        * @protected
        */
        postUpdate: function () {

            //  Only allow postUpdate to be called once per frame
            if (this.phase === 2)
            {
                return;
            }

            this.phase = 2;

            if (this.deltaX() < 0)
            {
                this.facing = Phaser.LEFT;
            }
            else if (this.deltaX() > 0)
            {
                this.facing = Phaser.RIGHT;
            }

            if (this.deltaY() < 0)
            {
                this.facing = Phaser.UP;
            }
            else if (this.deltaY() > 0)
            {
                this.facing = Phaser.DOWN;
            }

            if (this.moves)
            {
                this._dx = this.deltaX();
                this._dy = this.deltaY();

                if (this.deltaMax.x !== 0 && this._dx !== 0)
                {
                    if (this._dx < 0 && this._dx < -this.deltaMax.x)
                    {
                        this._dx = -this.deltaMax.x;
                    }
                    else if (this._dx > 0 && this._dx > this.deltaMax.x)
                    {
                        this._dx = this.deltaMax.x;
                    }
                }

                if (this.deltaMax.y !== 0 && this._dy !== 0)
                {
                    if (this._dy < 0 && this._dy < -this.deltaMax.y)
                    {
                        this._dy = -this.deltaMax.y;
                    }
                    else if (this._dy > 0 && this._dy > this.deltaMax.y)
                    {
                        this._dy = this.deltaMax.y;
                    }
                }

                this.sprite.x += this._dx;
                this.sprite.y += this._dy;
            }

            this.center.setTo(this.position.x + this.halfWidth, this.position.y + this.halfHeight);

            if (this.allowRotation)
            {
                this.sprite.angle += this.deltaZ();
            }

            this.prev.x = this.position.x;
            this.prev.y = this.position.y;

        },

        /**
        * Removes this bodies reference to its parent sprite, freeing it up for gc.
        *
        * @method Phaser.Physics.Arcade.Body#destroy
        */
        destroy: function () {

            this.sprite = null;

        },

        /**
        * Internal method.
        *
        * @method Phaser.Physics.Arcade.Body#checkWorldBounds
        * @protected
        */
        checkWorldBounds: function () {

            if (this.position.x < this.game.physics.arcade.bounds.x && this.game.physics.arcade.checkCollision.left)
            {
                this.position.x = this.game.physics.arcade.bounds.x;
                this.velocity.x *= -this.bounce.x;
                this.blocked.left = true;
            }
            else if (this.right > this.game.physics.arcade.bounds.right && this.game.physics.arcade.checkCollision.right)
            {
                this.position.x = this.game.physics.arcade.bounds.right - this.width;
                this.velocity.x *= -this.bounce.x;
                this.blocked.right = true;
            }

            if (this.position.y < this.game.physics.arcade.bounds.y && this.game.physics.arcade.checkCollision.up)
            {
                this.position.y = this.game.physics.arcade.bounds.y;
                this.velocity.y *= -this.bounce.y;
                this.blocked.up = true;
            }
            else if (this.bottom > this.game.physics.arcade.bounds.bottom && this.game.physics.arcade.checkCollision.down)
            {
                this.position.y = this.game.physics.arcade.bounds.bottom - this.height;
                this.velocity.y *= -this.bounce.y;
                this.blocked.down = true;
            }

        },

        /**
        * You can modify the size of the physics Body to be any dimension you need.
        * So it could be smaller or larger than the parent Sprite. You can also control the x and y offset, which
        * is the position of the Body relative to the top-left of the Sprite.
        *
        * @method Phaser.Physics.Arcade.Body#setSize
        * @param {number} width - The width of the Body.
        * @param {number} height - The height of the Body.
        * @param {number} offsetX - The X offset of the Body from the Sprite position.
        * @param {number} offsetY - The Y offset of the Body from the Sprite position.
        */
        setSize: function (width, height, offsetX, offsetY) {

            offsetX = offsetX || this.offset.x;
            offsetY = offsetY || this.offset.y;

            this.sourceWidth = width;
            this.sourceHeight = height;
            this.width = this.sourceWidth * this._sx;
            this.height = this.sourceHeight * this._sy;
            this.halfWidth = Math.floor(this.width / 2);
            this.halfHeight = Math.floor(this.height / 2);
            this.offset.setTo(offsetX, offsetY);

            this.center.setTo(this.position.x + this.halfWidth, this.position.y + this.halfHeight);

        },

        /**
        * Resets all Body values (velocity, acceleration, rotation, etc)
        *
        * @method Phaser.Physics.Arcade.Body#reset
        * @param {number} x - The new x position of the Body.
        * @param {number} y - The new y position of the Body.
        */
        reset: function (x, y) {

            this.velocity.set(0);
            this.acceleration.set(0);

            this.angularVelocity = 0;
            this.angularAcceleration = 0;

            this.position.x = (x - (this.sprite.anchor.x * this.width)) + this.offset.x;
            this.position.y = (y - (this.sprite.anchor.y * this.height)) + this.offset.y;

            this.prev.x = this.position.x;
            this.prev.y = this.position.y;

            this.rotation = this.sprite.angle;
            this.preRotation = this.rotation;

            this._sx = this.sprite.scale.x;
            this._sy = this.sprite.scale.y;

            this.center.setTo(this.position.x + this.halfWidth, this.position.y + this.halfHeight);

        },

        /**
        * Tests if a world point lies within this Body.
        *
        * @method Phaser.Physics.Arcade.Body#hitTest
        * @param {number} x - The world x coordinate to test.
        * @param {number} y - The world y coordinate to test.
        * @return {boolean} True if the given coordinates are inside this Body, otherwise false.
        */
        hitTest: function (x, y) {

            return Phaser.Rectangle.contains(this, x, y);

        },

        /**
        * Returns true if the bottom of this Body is in contact with either the world bounds or a tile.
        *
        * @method Phaser.Physics.Arcade.Body#onFloor
        * @return {boolean} True if in contact with either the world bounds or a tile.
        */
        onFloor: function () {
            return this.blocked.down;
        },

        /**
        * Returns true if either side of this Body is in contact with either the world bounds or a tile.
        *
        * @method Phaser.Physics.Arcade.Body#onWall
        * @return {boolean} True if in contact with either the world bounds or a tile.
        */
        onWall: function () {
            return (this.blocked.left || this.blocked.right);
        },

        /**
        * Returns the absolute delta x value.
        *
        * @method Phaser.Physics.Arcade.Body#deltaAbsX
        * @return {number} The absolute delta value.
        */
        deltaAbsX: function () {
            return (this.deltaX() > 0 ? this.deltaX() : -this.deltaX());
        },

        /**
        * Returns the absolute delta y value.
        *
        * @method Phaser.Physics.Arcade.Body#deltaAbsY
        * @return {number} The absolute delta value.
        */
        deltaAbsY: function () {
            return (this.deltaY() > 0 ? this.deltaY() : -this.deltaY());
        },

        /**
        * Returns the delta x value. The difference between Body.x now and in the previous step.
        *
        * @method Phaser.Physics.Arcade.Body#deltaX
        * @return {number} The delta value. Positive if the motion was to the right, negative if to the left.
        */
        deltaX: function () {
            return this.position.x - this.prev.x;
        },

        /**
        * Returns the delta y value. The difference between Body.y now and in the previous step.
        *
        * @method Phaser.Physics.Arcade.Body#deltaY
        * @return {number} The delta value. Positive if the motion was downwards, negative if upwards.
        */
        deltaY: function () {
            return this.position.y - this.prev.y;
        },

        /**
        * Returns the delta z value. The difference between Body.rotation now and in the previous step.
        *
        * @method Phaser.Physics.Arcade.Body#deltaZ
        * @return {number} The delta value. Positive if the motion was clockwise, negative if anti-clockwise.
        */
        deltaZ: function () {
            return this.rotation - this.preRotation;
        }

    };

    /**
    * @name Phaser.Physics.Arcade.Body#bottom
    * @property {number} bottom - The bottom value of this Body (same as Body.y + Body.height)
    * @readonly
    */
    Object.defineProperty(Phaser.Physics.Arcade.Body.prototype, "bottom", {

        get: function () {
            return this.position.y + this.height;
        }

    });

    /**
    * @name Phaser.Physics.Arcade.Body#right
    * @property {number} right - The right value of this Body (same as Body.x + Body.width)
    * @readonly
    */
    Object.defineProperty(Phaser.Physics.Arcade.Body.prototype, "right", {

        get: function () {
            return this.position.x + this.width;
        }

    });

    /**
    * @name Phaser.Physics.Arcade.Body#x
    * @property {number} x - The x position.
    */
    Object.defineProperty(Phaser.Physics.Arcade.Body.prototype, "x", {

        get: function () {
            return this.position.x;
        },

        set: function (value) {

            this.position.x = value;
        }

    });

    /**
    * @name Phaser.Physics.Arcade.Body#y
    * @property {number} y - The y position.
    */
    Object.defineProperty(Phaser.Physics.Arcade.Body.prototype, "y", {

        get: function () {
            return this.position.y;
        },

        set: function (value) {

            this.position.y = value;

        }

    });

    /**
    * Render Sprite Body.
    *
    * @method Phaser.Physics.Arcade.Body#renderDebug
    * @param {object} context - The context to render to.
    * @param {Phaser.Physics.Arcade.Body} body - The Body to render the info of.
    * @param {string} [color='rgb(255,255,255)'] - color of the debug info to be rendered. (format is css color string).
    * @param {boolean} [filled=true] - Render the objected as a filled (default, true) or a stroked (false)
    */
    Phaser.Physics.Arcade.Body.render = function (context, body, filled, color) {

        if (typeof filled === 'undefined') { filled = true; }

        color = color || 'rgba(0,255,0,0.4)';

        if (filled)
        {
            context.fillStyle = color;
            context.fillRect(body.position.x - body.game.camera.x, body.position.y - body.game.camera.y, body.width, body.height);
        }
        else
        {
            context.strokeStyle = color;
            context.strokeRect(body.position.x - body.game.camera.x, body.position.y - body.game.camera.y, body.width, body.height);
        }

    };

    /**
    * Render Sprite Body Physics Data as text.
    *
    * @method Phaser.Physics.Arcade.Body#renderBodyInfo
    * @param {Phaser.Physics.Arcade.Body} body - The Body to render the info of.
    * @param {number} x - X position of the debug info to be rendered.
    * @param {number} y - Y position of the debug info to be rendered.
    * @param {string} [color='rgb(255,255,255)'] - color of the debug info to be rendered. (format is css color string).
    */
    Phaser.Physics.Arcade.Body.renderBodyInfo = function (debug, body) {

        debug.line('x: ' + body.x.toFixed(2), 'y: ' + body.y.toFixed(2), 'width: ' + body.width, 'height: ' + body.height);
        debug.line('velocity x: ' + body.velocity.x.toFixed(2), 'y: ' + body.velocity.y.toFixed(2), 'deltaX: ' + body._dx.toFixed(2), 'deltaY: ' + body._dy.toFixed(2));
        debug.line('acceleration x: ' + body.acceleration.x.toFixed(2), 'y: ' + body.acceleration.y.toFixed(2), 'speed: ' + body.speed.toFixed(2), 'angle: ' + body.angle.toFixed(2));
        debug.line('gravity x: ' + body.gravity.x, 'y: ' + body.gravity.y, 'bounce x: ' + body.bounce.x.toFixed(2), 'y: ' + body.bounce.y.toFixed(2));
        debug.line('touching left: ' + body.touching.left, 'right: ' + body.touching.right, 'up: ' + body.touching.up, 'down: ' + body.touching.down);
        debug.line('blocked left: ' + body.blocked.left, 'right: ' + body.blocked.right, 'up: ' + body.blocked.up, 'down: ' + body.blocked.down);

    };

    Phaser.Physics.Arcade.Body.prototype.constructor = Phaser.Physics.Arcade.Body;