80 lines
3.0 KiB
JavaScript
80 lines
3.0 KiB
JavaScript
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// 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. No idea how the projection between
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// lat/lng and tiles works.
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// What follows now are functions that allow conversion between tiles
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// and lat/lng as well as calculating the quad key. The variable names
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// may be misleading.
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// The minified source for this code was in gen_dashboard.js after the
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// “// input 89” line (alternatively: the class was called “Xe”).
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window.convertCenterLat = function(centerLat) {
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return Math.round(256 * 0.9999 * Math.abs(1 / Math.cos(centerLat * DEG2RAD)));
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}
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window.calculateR = function(convCenterLat) {
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return 1 << window.map.getZoom() - (convCenterLat / 256 - 1);
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}
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window.convertLatLngToPoint = function(latlng, magic, R) {
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var x = (magic/2 + latlng.lng * magic / 360)*R;
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var l = Math.sin(latlng.lat * DEG2RAD);
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var y = (magic/2 + 0.5*Math.log((1+l)/(1-l)) * -(magic / (2*Math.PI)))*R;
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return {x: Math.floor(x/magic), y: Math.floor(y/magic)};
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}
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window.convertPointToLatLng = function(x, y, magic, R) {
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var e = {};
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e.sw = {
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// orig function put together from all over the place
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// lat: (2 * Math.atan(Math.exp((((y + 1) * magic / R) - (magic/ 2)) / (-1*(magic / (2 * Math.PI))))) - Math.PI / 2) / (Math.PI / 180),
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// shortened version by your favorite algebra program.
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lat: (360*Math.atan(Math.exp(Math.PI - 2*Math.PI*(y+1)/R)))/Math.PI - 90,
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lng: 360*x/R-180
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};
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e.ne = {
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//lat: (2 * Math.atan(Math.exp(((y * magic / R) - (magic/ 2)) / (-1*(magic / (2 * Math.PI))))) - Math.PI / 2) / (Math.PI / 180),
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lat: (360*Math.atan(Math.exp(Math.PI - 2*Math.PI*y/R)))/Math.PI - 90,
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lng: 360*(x+1)/R-180
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};
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return e;
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}
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// calculates the quad key for a given point. The point is not(!) in
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// lat/lng format.
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window.pointToQuadKey = function(x, y) {
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var quadkey = [];
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for(var c = window.map.getZoom(); c > 0; c--) {
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// +-------+ quadrants are probably ordered like this
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// | 0 | 1 |
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// |---|---|
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// | 2 | 3 |
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// |---|---|
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var quadrant = 0;
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var e = 1 << c - 1;
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(x & e) != 0 && quadrant++; // push right
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(y & e) != 0 && (quadrant++, quadrant++); // push down
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quadkey.push(quadrant);
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}
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return quadkey.join("");
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}
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// given quadkey and bounds, returns the format as required by the
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// Ingress API to request map data.
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window.generateBoundsParams = function(quadkey, bounds) {
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return {
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id: quadkey,
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qk: quadkey,
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minLatE6: Math.round(bounds.sw.lat * 1E6),
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minLngE6: Math.round(bounds.sw.lng * 1E6),
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maxLatE6: Math.round(bounds.ne.lat * 1E6),
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maxLngE6: Math.round(bounds.ne.lng * 1E6)
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};
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}
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