spatialManager.js

// ==========
// SPATIAL MANAGER
// ==========

/*

spatialManager.js

A module which handles spatial lookup, as required for...
e.g. general collision detection.

*/

"use strict";

/* jshint browser: true, devel: true, globalstrict: true */

/*
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*/

var spatialManager = {

// "PRIVATE" DATA

_nextSpatialID : 1, // make all valid IDs non-falsey (i.e. don't start at 0)

_entities : [],
_entitiesSq : [],

// "PRIVATE" METHODS
//
// <none yet>


// PUBLIC METHODS

getNewSpatialID : function() {

    var id = this._nextSpatialID; //id variable that holds the current spatial ID
    this._nextSpatialID++; //increase the spatial ID by 1
    
    return id; //return the current spatial ID
},

register: function(entity) {
    var pos = entity.getPos();
    var spatialID = entity.getSpatialID();
    
    //Let the spatial entity with the current s ID inherit all attributes from the entity
    this._entities[spatialID] = entity; 
    this._entities[spatialID].posX = pos.posX;
    this._entities[spatialID].posY = pos.posY;
    this._entities[spatialID].radius = entity.getRadius();
},

unregister: function(entity) {
    var spatialID = entity.getSpatialID();

    delete this._entities[spatialID]; //Delete the entity from spatial manager
},

registerSq: function(entity) {
    var pos = entity.getPos();
    var rad = entity.getRadius();
    var spatialID = entity.getSpatialID();
    
    
    this._entitiesSq[spatialID] = entity; 
    this._entitiesSq[spatialID].posX = pos.posX;
    this._entitiesSq[spatialID].posY = pos.posY;
    this._entitiesSq[spatialID].width = rad.width;
    this._entitiesSq[spatialID].height = rad.height;
},

unregisterSq: function(entity) {
    var spatialID = entity.getSpatialID();

    delete this._entitiesSq[spatialID];
},

findEntityInRange: function(posX, posY, radius) {

    //For every ID in the spatial entities array, find an entity in range and return it
    for (var ID in this._entities) {
        var e = this._entities[ID];
        var dist = util.distSq(e.posX, e.posY, posX, posY, g_canvas.width, g_canvas.height);
        if (util.square(radius + e.radius) > dist) {
            return e; 
        }
    }

    // Also check square entities
    for (var ID2 in this._entitiesSq) {
        var e2 = this._entitiesSq[ID2];
        var dX = posX - Math.max(e2.posX, Math.min(posX, e2.posX + e2.width));
        var dY = posY - Math.max(e2.posY, Math.min(posY, e2.posY + e2.height));
        if ((dX * dX + dY * dY) < (radius * radius)) {
            return e2;
        }
    }

},

render: function(ctx) {
    var oldStyle = ctx.strokeStyle;
    ctx.strokeStyle = "red";
    
    for (var ID in this._entities) {
        var e = this._entities[ID];
        util.strokeCircle(ctx, e.posX, e.posY, e.radius);
    }

    var oldWidth = ctx.lineWidth;
    ctx.lineWidth = 2;

    for (var ID2 in this._entitiesSq) {
        var e2 = this._entitiesSq[ID2];
        util.strokeRect(ctx, e2.posX, e2.posY, e2.width, e2.height);
    }

    ctx.strokeStyle = oldStyle;
    ctx.lineWidth = oldWidth;
}

}