missing file, refs #43

lib/torque/mercator.js

@@ -0,0 +1,93 @@
+
+(function(exports) {
+
+var Point = function(x, y) {
+  this.x = x || 0;
+  this.y = y || 0;
+};
+
+function clamp(value, optMin, optMax) {
+  if (optMin !== null) value = Math.max(value, optMin);
+  if (optMax !== null) value = Math.min(value, optMax);
+  return value;
+}
+
+function degreesToRadians(deg) {
+  return deg * (Math.PI / 180);
+}
+
+function radiansToDegrees(rad) {
+  return rad / (Math.PI / 180);
+}
+
+
+var MercatorProjection = exports.torque.Mercator = function() {
+//  this._tileSize = L.Browser.retina ? 512 : 256;
+  this._tileSize = 256;
+  this._pixelOrigin = new Point(this._tileSize / 2, this._tileSize / 2);
+  this._pixelsPerLonDegree = this._tileSize / 360;
+  this._pixelsPerLonRadian = this._tileSize / (2 * Math.PI);
+};
+
+MercatorProjection.prototype._fromLatLonToPoint = function(lat, lon) {
+  var point = new Point(0, 0);
+  var origin = this._pixelOrigin;
+
+  point.x = origin.x + lon * this._pixelsPerLonDegree;
+
+  // NOTE(appleton): Truncating to 0.9999 effectively limits latitude to
+  // 89.189.  This is about a third of a tile past the edge of the world
+  // tile.
+  var siny = clamp(Math.sin(degreesToRadians(lat)), -0.9999, 0.9999);
+  point.y = origin.y + 0.5 * Math.log((1 + siny) / (1 - siny)) * -this._pixelsPerLonRadian;
+  return point;
+};
+
+MercatorProjection.prototype._fromPointToLatLon = function(point) {
+  var me = this;
+  var origin = me._pixelOrigin;
+  var lon = (point.x - origin.x) / me._pixelsPerLonDegree;
+  var latRadians = (point.y - origin.y) / -me._pixelsPerLonRadian;
+  var lat = radiansToDegrees(2 * Math.atan(Math.exp(latRadians)) - Math.PI / 2);
+  return { lat:lat, lon:lon };
+};
+
+MercatorProjection.prototype._tilePixelPos = function(tileX, tileY) {
+  return {
+    x: tileX*this._tileSize,
+    y: tileY*this._tileSize
+  };
+};
+
+MercatorProjection.prototype.tilePixelBBox = function(x, y, zoom, px, py) {
+  var numTiles = 1 <<zoom;
+  var inc = 1.0/numTiles;
+  px = (x*this._tileSize + px)/numTiles;
+  py = (y*this._tileSize + py)/numTiles;
+  return [
+    this._fromPointToLatLon(new Point(px, py + inc)),
+    this._fromPointToLatLon(new Point(px + inc, py))
+  ];
+};
+
+MercatorProjection.prototype.tileBBox = function(x, y, zoom, bufferSize) {
+  var numTiles = 1 <<zoom;
+  bufferSize = bufferSize || 0;
+  var inc =  (this._tileSize + bufferSize*2)/numTiles;
+  var px = (x*this._tileSize - bufferSize  )/numTiles;
+  var py = (y*this._tileSize - bufferSize  )/numTiles;
+  return [
+    this._fromPointToLatLon(new Point(px, py + inc)),
+    this._fromPointToLatLon(new Point(px + inc, py))
+  ];
+};
+
+MercatorProjection.prototype.latLonToTilePoint = function(lat, lon, tileX, tileY, zoom) {
+  var numTiles = 1 <<zoom;
+  var worldCoordinate = this._fromLatLonToPoint(lat, lon);
+  var pixelCoordinate = new Point(worldCoordinate.x*numTiles, worldCoordinate.y*numTiles);
+  var tilePixelPos    = this._tilePixelPos(tileX, tileY);
+  return new Point(Math.round(pixelCoordinate.x-tilePixelPos.x), Math.round(pixelCoordinate.y-tilePixelPos.y));
+};
+
+})(typeof exports === "undefined" ? this : exports);