QuadTree.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}
*/

/**
* Javascript QuadTree 
* @version 1.0
* @author Timo Hausmann
*
* @version 1.2, September 4th 2013
* @author Richard Davey
* The original code was a conversion of the Java code posted to GameDevTuts. However I've tweaked
* it massively to add node indexing, removed lots of temp. var creation and significantly
* increased performance as a result.
*
* Original version at https://github.com/timohausmann/quadtree-js/
*/
 
/**
* @copyright © 2012 Timo Hausmann
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

/**
* QuadTree Constructor
* 
* @class Phaser.QuadTree
* @classdesc A QuadTree implementation. The original code was a conversion of the Java code posted to GameDevTuts. 
* However I've tweaked it massively to add node indexing, removed lots of temp. var creation and significantly increased performance as a result. 
* Original version at https://github.com/timohausmann/quadtree-js/
* @constructor
* @param {number} x - The top left coordinate of the quadtree.
* @param {number} y - The top left coordinate of the quadtree.
* @param {number} width - The width of the quadtree in pixels.
* @param {number} height - The height of the quadtree in pixels.
* @param {number} [maxObjects=10] - The maximum number of objects per node.
* @param {number} [maxLevels=4] - The maximum number of levels to iterate to.
* @param {number} [level=0] - Which level is this?
*/
Phaser.QuadTree = function (x, y, width, height, maxObjects, maxLevels, level) {
        
    this.maxObjects = maxObjects || 10;
    this.maxLevels = maxLevels || 4;
    this.level = level || 0;

    this.bounds = {
        x: Math.round(x),
        y: Math.round(y),
        width: width,
        height: height,
        subWidth: Math.floor(width / 2),
        subHeight: Math.floor(height / 2),
        right: Math.round(x) + Math.floor(width / 2),
        bottom: Math.round(y) + Math.floor(height / 2)
    };
    
    this.objects = [];
    this.nodes = [];

};

Phaser.QuadTree.prototype = {

    /*
    * Populates this quadtree with the members of the given Group.
    * 
    * @method Phaser.QuadTree#populate
    * @param {Phaser.Group} group - The Group to add to the quadtree.
    */
    populate: function (group) {

        group.forEach(this.populateHandler, this, true);

    },

    /*
    * Handler for the populate method.
    * 
    * @method Phaser.QuadTree#populateHandler
    * @param {Phaser.Sprite} sprite - The Sprite to check.
    */
    populateHandler: function (sprite) {

        if (sprite.body && sprite.body.checkCollision.none === false && sprite.alive)
        {
            this.insert(sprite.body);
        }

    },

    /*
    * Split the node into 4 subnodes
    * 
    * @method Phaser.QuadTree#split
    */
    split: function () {

        this.level++;
        
        //  top right node
        this.nodes[0] = new Phaser.QuadTree(this.bounds.right, this.bounds.y, this.bounds.subWidth, this.bounds.subHeight, this.maxObjects, this.maxLevels, this.level);
        
        //  top left node
        this.nodes[1] = new Phaser.QuadTree(this.bounds.x, this.bounds.y, this.bounds.subWidth, this.bounds.subHeight, this.maxObjects, this.maxLevels, this.level);
        
        //  bottom left node
        this.nodes[2] = new Phaser.QuadTree(this.bounds.x, this.bounds.bottom, this.bounds.subWidth, this.bounds.subHeight, this.maxObjects, this.maxLevels, this.level);
        
        //  bottom right node
        this.nodes[3] = new Phaser.QuadTree(this.bounds.right, this.bounds.bottom, this.bounds.subWidth, this.bounds.subHeight, this.maxObjects, this.maxLevels, this.level);

    },

    /*
    * Insert the object into the node. If the node exceeds the capacity, it will split and add all objects to their corresponding subnodes.
    * 
    * @method Phaser.QuadTree#insert
    * @param {Phaser.Physics.Arcade.Body|object} body - The Body object to insert into the quadtree.
    */
    insert: function (body) {
        
        var i = 0;
        var index;
        
        //  if we have subnodes ...
        if (this.nodes[0] != null)
        {
            index = this.getIndex(body);
     
            if (index !== -1)
            {
                this.nodes[index].insert(body);
                return;
            }
        }
     
        this.objects.push(body);
        
        if (this.objects.length > this.maxObjects && this.level < this.maxLevels)
        {
            //  Split if we don't already have subnodes
            if (this.nodes[0] == null)
            {
                this.split();
            }
            
            //  Add objects to subnodes
            while (i < this.objects.length)
            {
                index = this.getIndex(this.objects[i]);
                
                if (index !== -1)
                {
                    //  this is expensive - see what we can do about it
                    this.nodes[index].insert(this.objects.splice(i, 1)[0]);
                }
                else
                {
                    i++;
                }
            }
        }

    },
     
    /*
    * Determine which node the object belongs to.
    * 
    * @method Phaser.QuadTree#getIndex
    * @param {Phaser.Rectangle|object} rect - The bounds in which to check.
    * @return {number} index - Index of the subnode (0-3), or -1 if rect cannot completely fit within a subnode and is part of the parent node.
    */
    getIndex: function (rect) {
        
        //  default is that rect doesn't fit, i.e. it straddles the internal quadrants
        var index = -1;

        if (rect.x < this.bounds.right && rect.right < this.bounds.right)
        {
            if ((rect.y < this.bounds.bottom && rect.bottom < this.bounds.bottom))
            {
                //  rect fits within the top-left quadrant of this quadtree
                index = 1;
            }
            else if ((rect.y > this.bounds.bottom))
            {
                //  rect fits within the bottom-left quadrant of this quadtree
                index = 2;
            }
        }
        else if (rect.x > this.bounds.right)
        {
            //  rect can completely fit within the right quadrants
            if ((rect.y < this.bounds.bottom && rect.bottom < this.bounds.bottom))
            {
                //  rect fits within the top-right quadrant of this quadtree
                index = 0;
            }
            else if ((rect.y > this.bounds.bottom))
            {
                //  rect fits within the bottom-right quadrant of this quadtree
                index = 3;
            }
        }
     
        return index;

    },

    /*
    * Return all objects that could collide with the given Sprite.
    * 
    * @method Phaser.QuadTree#retrieve
    * @param {Phaser.Sprite} sprite - The sprite to check against.
    * @return {array} - Array with all detected objects.
    */
    retrieve: function (sprite) {
        
        var returnObjects = this.objects;

        sprite.body.quadTreeIndex = this.getIndex(sprite.body);

        //  Temp store for the node IDs this sprite is in, we can use this for fast elimination later
        // sprite.body.quadTreeIDs.push(this.ID);

        if (this.nodes[0])
        {
            //  if rect fits into a subnode ..
            if (sprite.body.quadTreeIndex !== -1)
            {
                returnObjects = returnObjects.concat(this.nodes[sprite.body.quadTreeIndex].retrieve(sprite));
            }
            else
            {
                //  if rect does not fit into a subnode, check it against all subnodes (unrolled for speed)
                returnObjects = returnObjects.concat(this.nodes[0].retrieve(sprite));
                returnObjects = returnObjects.concat(this.nodes[1].retrieve(sprite));
                returnObjects = returnObjects.concat(this.nodes[2].retrieve(sprite));
                returnObjects = returnObjects.concat(this.nodes[3].retrieve(sprite));
            }
        }
     
        return returnObjects;

    },

    /*
    * Clear the quadtree.
    * @method Phaser.QuadTree#clear
    */
    clear: function () {
        
        this.objects = [];
     
        for (var i = 0, len = this.nodes.length; i < len; i++)
        {
            if (this.nodes[i])
            {
                this.nodes[i].clear();
                delete this.nodes[i];
            }
        }
    }

};

Phaser.QuadTree.prototype.constructor = Phaser.QuadTree;