so others may contribute

code/map_data_calc_tools.js

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