pastebin

 

$zoom = (int) htmlspecialchars($_GET["zoom"]);

$x = (int) htmlspecialchars($_GET["x"]);

$y = (int) htmlspecialchars($_GET["y"]);

 

$y = pow(2, $zoom)-$y-1;

 

function get_tile_bbox($x,$y,$z) {

  $merc1 = get_merc_coords($x * 256, $y * 256, $z);

  $merc2 = get_merc_coords(($x + 1) * 256, ($y + 1) * 256, $z);

 

  $min_x = $merc1['merc_x']; $min_y = $merc1['merc_y'];

  $max_x = $merc2['merc_x']; $max_y = $merc2['merc_y'];

  return $min_x.",".$min_y.",".$max_x.",".$max_y;

 

function get_merc_coords($x,$y,$z) {

  $resolution = (2 * pi() * 6378137 / 256) / (pow(2,$z));

  $merc_x = ($x * $resolution - 2 * pi() * 6378137 / 2.0);

  $merc_y = ($y * $resolution - 2 * pi() * 6378137 / 2.0);

  return compact('merc_x', 'merc_y');

 

$bbox = get_tile_bbox($x,$y,$zoom);

 

header('Location: http://apollo.cdngiportal.co.za/erdas-iws/ogc/wms/CDNGI_PORTAL_BACKDROP?FORMAT=image/jpeg&VERSION=1.1.1&SERVICE=WMS&REQUEST=GetMap&LAYERS=CDNGI_50K_1stEdition_Mosaic&STYLES=&SRS=EPSG:3857&WIDTH=256&HEIGHT=256&BBOX='.$bbox);