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troggle/media/jslib/CaveView/lib/BGS.js
2021-04-02 19:02:10 +01:00

35 lines
822 B
JavaScript

function BGSTileURL ( x, y, z ) {
var earthRadius = 6378137; // in meters
var tileCount = Math.pow( 2, z );
var tileSize = earthRadius * 2 * Math.PI / tileCount;
var x1, x2, y1, y2;
x = x - tileCount / 2;
y = tileCount / 2 - y;
x1 = x * tileSize;
y1 = y * tileSize;
x2 = x1 + tileSize;
y2 = y1 + tileSize;
var url = 'https://map.bgs.ac.uk/arcgis/services/BGS_Detailed_Geology/MapServer/WMSServer?REQUEST=GetMap&VERSION=1.3.0&LAYERS=BGS.50k.Bedrock&STYLES=default&FORMAT=image/png&CRS=EPSG:3857&WIDTH=450&HEIGHT=450';
var bbox = '&BBOX=' + x1 + ',' + y1 + ',' + x2 + ',' + y2;
console.log( 'BGS: ', bbox );
// var img = document.createElement( 'img' );
// img.src = url + bbox;
// img.crossOrigin = '';
// document.body.appendChild( img );
return url + bbox;
}