59 lines
2.0 KiB
JavaScript
59 lines
2.0 KiB
JavaScript
// MAP DATA REQUEST CALCULATORS //////////////////////////////////////
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// Ingress Intel splits up requests for map data (portals, links,
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// fields) into tiles. To get data for the current viewport (i.e. what
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// is currently visible) it first calculates which tiles intersect.
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// For all those tiles, it then calculates the lat/lng bounds of that
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// tile and a quadkey. Both the bounds and the quadkey are “somewhat”
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// required to get complete data.
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//
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// Conversion functions courtesy of
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// http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames
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window.zoomToTilesPerEdge = function(zoom) {
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// var LEVEL_TO_TILES_PER_EDGE = [65536, 65536, 16384, 16384, 4096, 1536, 1024, 256, 32];
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// return LEVEL_TO_TILES_PER_EDGE[level];
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var ZOOM_TO_TILES_PER_EDGE = [32, 32, 32, 32, 256, 256, 256, 1024, 1024, 1536, 4096, 4096, 16384, 16384, 16384];
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return ZOOM_TO_TILES_PER_EDGE[zoom] || 65536;
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}
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window.lngToTile = function(lng, zoom) {
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return Math.floor((lng + 180) / 360 * zoomToTilesPerEdge(zoom));
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}
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window.latToTile = function(lat, zoom) {
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return Math.floor((1 - Math.log(Math.tan(lat * Math.PI / 180) +
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1 / Math.cos(lat * Math.PI / 180)) / Math.PI) / 2 * zoomToTilesPerEdge(zoom));
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}
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window.tileToLng = function(x, zoom) {
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return x / zoomToTilesPerEdge(zoom) * 360 - 180;
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}
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window.tileToLat = function(y, zoom) {
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var n = Math.PI - 2 * Math.PI * y / zoomToTilesPerEdge(zoom);
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return 180 / Math.PI * Math.atan(0.5 * (Math.exp(n) - Math.exp(-n)));
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}
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window.pointToTileId = function(zoom, x, y) {
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return zoom + "_" + x + "_" + y;
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}
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window.getResonatorLatLng = function(dist, slot, portalLatLng) {
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// offset in meters
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var dn = dist*SLOT_TO_LAT[slot];
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var de = dist*SLOT_TO_LNG[slot];
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// Coordinate offset in radians
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var dLat = dn/EARTH_RADIUS;
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var dLon = de/(EARTH_RADIUS*Math.cos(Math.PI/180*portalLatLng[0]));
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// OffsetPosition, decimal degrees
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var lat0 = portalLatLng[0] + dLat * 180/Math.PI;
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var lon0 = portalLatLng[1] + dLon * 180/Math.PI;
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return [lat0, lon0];
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}
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