/*
Call generic wms service for GoogleMaps v2
John Deck, UC Berkeley
Inspiration & Code from:
	Mike Williams http://www.econym.demon.co.uk/googlemaps2/ V2 Reference & custommap code
	Brian Flood http://www.spatialdatalogic.com/cs/blogs/brian_flood/archive/2005/07/11/39.aspx V1 WMS code
	Kyle Mulka http://blog.kylemulka.com/?p=287  V1 WMS code modifications
	http://search.cpan.org/src/RRWO/GPS-Lowrance-0.31/lib/Geo/Coordinates/MercatorMeters.pm
*/

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="default"; 
	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=1.1.1";
	lURL+="&LAYERS="+this.myLayers;
	lURL+="&STYLES="+this.myStyles; lURL+="&FORMAT="+this.myFormat;
	lURL+="&BGCOLOR=0xFFFFFF";
	lURL+="&TRANSPARENT=TRUE";
	lURL+="&SRS="+lSRS;
	lURL+="&BBOX="+lBbox;
	lURL+="&WIDTH=256";
	lURL+="&HEIGHT=256";
	lURL+="&reaspect=false";
	return lURL;
}