entities.js

function EntityTracker(world) {
	this.world = world;
	this.entity_areas = {};
	this.entity_uids = {};
}

var GATHER_RADIUS = 4 * 32;
var AREA_MAG = 5;


EntityTracker.prototype.spawnEntity = function (x, y, z, type, yaw, pitch, velocity) {
	var entity_index = [x >> AREA_MAG, z >> AREA_MAG];

	if (!(entity_index in this.entity_areas)) {
		this.entity_areas[entity_index] = [];
	}

	var entity = {
		uid: this.world.uidgen.allocate(),
		x: x,
		y: y,
		z: z,
		type: type,
		yaw: yaw,
		pitch: pitch,
		velocity: velocity
	};

	this.entity_areas[entity_index].push(entity);
	this.entity_uids[entity.uid] = entity;

	return entity;
};

EntityTracker.prototype.findPickups = function (x, y, z) {
	var pickups = [];

	var x_index = x >> AREA_MAG;
	var z_index = z >> AREA_MAG;

	for (var x_i = x_index - 1; x_i <= x_index + 1; x_i++) {
		for (var z_i = z_index - 1; z_i <= z_index + 1; z_i++) {
			var entity_index = [x_i, z_i];
			if (entity_index in this.entity_areas) {
				var entity_list = this.entity_areas[entity_index];

				for (var i = 0; i < entity_list.length; i++) {
					var entity = entity_list[i];

					var x_d = entity.x - x;
					var y_d = entity.y - y;
					var z_d = entity.z - z;

					if (Math.sqrt(x_d * x_d + y_d * y_d + z_d * z_d) < GATHER_RADIUS) {
						pickups.push(entity);
					}
				}
			}
		}
	}

	return pickups;
};

EntityTracker.prototype.destroyEntity = function (uid) {

	var entity = this.entity_uids[uid];
	delete this.entity_uids[uid];

	if (!entity) {
		return;
	}

	var x_index = entity.x >> AREA_MAG;
	var z_index = entity.z >> AREA_MAG;

	var entity_index = [x_index, z_index];

	var entity_list = this.entity_areas[entity_index];

	for (var i = 0; i < entity_list.length; i++) {
		if (entity_list[i].uid == uid) {
			entity_list.splice(i, 1);
			break;
		}
	}

};

module.exports.EntityTracker = EntityTracker;