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Add tile calculations

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pietervdvn 2021-03-14 20:15:11 +01:00
parent 19582853f5
commit 0d7ee51206
1 changed files with 35 additions and 0 deletions
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35
Utils.ts
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@ -183,4 +183,39 @@ export class Utils {
return dict.get(k);
}
/**
* Calculates the tile bounds of the
* @param z
* @param x
* @param y
* @returns [[lat, lon], [lat, lon]]
*/
static tile_bounds(z: number, x: number, y: number): [[number, number], [number, number]] {
return [[Utils.tile2lat(y, z), Utils.tile2long(x, z)], [Utils.tile2lat(y + 1, z), Utils.tile2long(x + 1, z)]]
}
/**
* Return x, y of the tile containing (lat, lon) on the given zoom level
*/
static embedded_tile(lat: number, lon: number, z: number): { x: number, y: number, z: number } {
return {x: Utils.lon2tile(lon, z), y: Utils.lat2tile(lat, z), z: z}
}
private static tile2long(x, z) {
return (x / Math.pow(2, z) * 360 - 180);
}
private static tile2lat(y, z) {
const n = Math.PI - 2 * Math.PI * y / Math.pow(2, z);
return (180 / Math.PI * Math.atan(0.5 * (Math.exp(n) - Math.exp(-n))));
}
private static lon2tile(lon, zoom) {
return (Math.floor((lon + 180) / 360 * Math.pow(2, zoom)));
}
private static lat2tile(lat, zoom) {
return (Math.floor((1 - Math.log(Math.tan(lat * Math.PI / 180) + 1 / Math.cos(lat * Math.PI / 180)) / Math.PI) / 2 * Math.pow(2, zoom)));
}
}