/*
 * Create GoogleMap WMS (transparent) layers on any GoogleMap.
 *
 * Just van den Broecke - just AT justobjects.nl - www.justobjects.nl - www.geoskating.com
 * version: $Id: GMap.js 201 2006-11-25 11:59:49Z just $
 *
 * This (experimental) code can be downloaded from
 * http://www.geotracing.com/gt/script/gmap.js
 *
 * CREDITS
 * This code is based on and inspired by:
 * Brian Flood - http://www.spatialdatalogic.com/cs/blogs/brian_flood/archive/2005/07/11/39.aspx and
 * Kyle Mulka - http://blog.kylemulka.com/?p=287
 * I have merely merged the two approaches taken by each of these great minds !
 *
 */

var MAGIC_NUMBER = 6356752.3142;
var DEG2RAD = 0.0174532922519943;
var PI = 3.14159267;
function dd2MercMetersLng(p_lng) {
	return MAGIC_NUMBER * (p_lng * DEG2RAD);
}

function dd2MercMetersLat(p_lat) {
	if (p_lat >= 85) p_lat = 85;
	if (p_lat <= -85) p_lat = -85;
	return MAGIC_NUMBER * Math.log(Math.tan(((p_lat * DEG2RAD) + (PI / 2)) / 2));
}

CustomGetTileUrl = function(a, b, c) {
	if (typeof(window['this.myMercZoomLevel']) == "undefined") this.myMercZoomLevel = 0;
	if (typeof(window['this.myStyles']) == "undefined") this.myStyles = "";
	var lULP = new GPoint(a.x * 256, (a.y + 1) * 256);
	var lLRP = new GPoint((a.x + 1) * 256, a.y * 256);
	var lUL = G_NORMAL_MAP.getProjection().fromPixelToLatLng(lULP, b, c);
	var lLR = G_NORMAL_MAP.getProjection().fromPixelToLatLng(lLRP, b, c);
	// switch between Mercator and DD if merczoomlevel is set
	if (this.myMercZoomLevel != 0 && map.getZoom() < this.myMercZoomLevel) {
		var lBbox = dd2MercMetersLng(lUL.lngDegrees) + "," + dd2MercMetersLat(lUL.latDegrees) + "," + dd2MercMetersLng(lLR.lngDegrees) + "," + dd2MercMetersLat(lLR.latDegrees);
		var lSRS = "EPSG:54004";
	} else {
		var lBbox = lUL.x + "," + lUL.y + "," + lLR.x + "," + lLR.y;
		var lSRS = "EPSG:4326";
	}
	var lURL = this.myBaseURL;
	lURL += "&REQUEST=GetMap";
	lURL += "&SERVICE=WMS";
	lURL += "&VERSION=" + this.myVersion;
	//lURL += "&LAYERS=" + this.myLayers;
	lURL += "&STYLES=" + this.myStyles;
	lURL += "&FORMAT=" + this.myFormat;
	//lURL += "&BGCOLOR=" + this.myBgColor;
	lURL += "&TRANSPARENT=TRUE";
	lURL += "&SRS=" + lSRS;
	lURL += "&BBOX=" + lBbox;
	lURL += "&WIDTH=256";
	lURL += "&HEIGHT=256";
	lURL += "&reaspect=false";
	return lURL;
}