56 lines
1.8 KiB
C
56 lines
1.8 KiB
C
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/*
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open source routing machine
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Copyright (C) Dennis Luxen, others 2010
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU AFFERO General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU Affero General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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or see http://www.gnu.org/licenses/agpl.txt.
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*/
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#ifndef PROJECTIONUTILS_H_
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#define PROJECTIONUTILS_H_
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#include <cmath>
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namespace ProjectionUtils {
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inline long googleMaxTiles(int zoom) { return( 1L << (17 - zoom) ); }
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inline void googleX_to_lng(int zoom, double x, double& lng) {
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long tilesAtThisZoom =googleMaxTiles(zoom);
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lng = -180.0 + (x * 360.0 / double(tilesAtThisZoom));
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}
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inline void googleY_to_lat(int zoom, double y, double& lat) {
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// This function is the inverse Mercator projection.
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// Look up 'Mercator projection' on Wikipedia for details.
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long pixels = googleMaxTiles(zoom) * 256L;
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double pixelsPerLonRadian = pixels / (2.0 * M_PI);
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double bitmapOrigo = pixels / 2;
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double Y = (bitmapOrigo - y*256) / pixelsPerLonRadian;
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double latRad = 2.0 * ::atan( ::exp(Y) ) - M_PI_2;
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lat = latRad * 180.0 / M_PI;
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}
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inline void googleXY_to_latlng( double x, double y, int zoom, double& lng, double& lat ) {
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googleX_to_lng(zoom,x,lng);
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googleY_to_lat(zoom,y,lat);
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}
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}
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#endif /* PROJECTIONUTILS_H_ */
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