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/*------------------------------------------------------------------------------
*
* This file is part of rendermq
*
* Author: artem@mapnik-consulting.com
*
* Copyright 2010-1 Mapquest, Inc. All Rights reserved.
*
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*-----------------------------------------------------------------------------*/
#ifndef SPHERICAL_MERCATOR_HPP
#define SPHERICAL_MERCATOR_HPP
#ifndef M_PI
#define M_PI 3.141592653589793238462643
#endif
#define RAD_TO_DEG (180/M_PI)
#define DEG_TO_RAD (M_PI/180)
#include <cmath>
namespace rendermq
{
template <int levels=19>
class spherical_mercator
{
double Ac[levels];
double Bc[levels];
double Cc[levels];
double zc[levels];
public:
spherical_mercator()
{
int d, c = 256;
for (d=0; d<levels; d++) {
int e = c/2;
Bc[d] = c/360.0;
Cc[d] = c/(2 * M_PI);
zc[d] = e;
Ac[d] = c;
c *=2;
}
}
void to_pixels(double &x, double &y, int zoom)
{
double d = zc[zoom];
double f = minmax(std::sin(DEG_TO_RAD * y),-0.9999,0.9999);
x = round(d + x * Bc[zoom]);
y = round(d + 0.5*std::log((1+f)/(1-f))*-Cc[zoom]);
}
void from_pixels(double &x, double &y, int zoom)
{
double e = zc[zoom];
double g = (y - e)/-Cc[zoom];
x = (x - e)/Bc[zoom];
y = RAD_TO_DEG * ( 2 * atan(exp(g)) - 0.5 * M_PI);
}
private:
double minmax(double a, double b, double c)
{
#define LOCAL_MIN(x,y) ((x)<(y)?(x):(y))
#define LOCAL_MAX(x,y) ((x)>(y)?(x):(y))
a = LOCAL_MAX(a,b);
a = LOCAL_MIN(a,c);
return a;
#undef LOCAL_MIN
#undef LOCAL_MAX
}
};
}
#endif //SPHERICAL_MERCATOR_HPP