Google co-ordinate system ... PHP code

There's little documentation to convert Google Maps 3 co-ordinates to WGS84 latitude/longitude, here's my handy little function...

^{Brian Butterworth published on UK Free TV 19th March 2010 at 19:07}

Just spent a few annoying hours working this function out.

Google Maps 3 API, the one I'm using to upgrade this site, has a fantastic overlay system, but I was left with Google Maps "x,y,zoom" data in PHP, and I wanted LatLng format to quiz the database. You can do this using the Projection.fromPointToLatLng() Javascript function, but you don't have access to these in the PHP server encironment. So here's the replacement:

function fromPointToLatLng($intX, $intY, $intZoom)
{
$c=pow(2,$intZoom);
$x=360/$c*$intX-180;
$y=180-360/$c*$intY;
$fpLong=$x; 
$fpLat= (2.0*atan(exp($y /180*M_PI))-M_PI/2.0)*180/M_PI;
return array( $fpLat, $fpLong);
}

Such that:

list($fpLat, $fpLong)=fromPointToLatLng($intX, $intY, $intZoom);

For more, see Maps API V3 Overlays - Google Maps JavaScript API V3 - Google Code