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#ifndef MBGL_UTIL_PROJECTION
#define MBGL_UTIL_PROJECTION
#include <mbgl/util/constants.hpp>
#include <mbgl/util/geo.hpp>
#include <cmath>
namespace mbgl {
class Projection {
public:
static inline void getWorldBoundsMeters(ProjectedMeters &sw, ProjectedMeters &ne) {
const double d = util::EARTH_RADIUS_M * M_PI;
sw.easting = -d;
sw.northing = -d;
ne.easting = d;
ne.northing = d;
}
static inline void getWorldBoundsLatLng(LatLng &sw, LatLng &ne) {
ProjectedMeters projectedMetersSW = ProjectedMeters();
ProjectedMeters projectedMetersNE = ProjectedMeters();
getWorldBoundsMeters(projectedMetersSW, projectedMetersNE);
sw = latLngForProjectedMeters(projectedMetersSW);
ne = latLngForProjectedMeters(projectedMetersNE);
}
static inline double getMetersPerPixelAtLatitude(const double lat, const double zoom) {
const double mapPixelWidthAtZoom = std::pow(2.0, zoom) * util::tileSize;
const double constrainedLatitude = std::fmin(std::fmax(lat, -util::LATITUDE_MAX), util::LATITUDE_MAX);
return std::cos(constrainedLatitude * util::DEG2RAD) * util::M2PI * util::EARTH_RADIUS_M / mapPixelWidthAtZoom;
}
static inline const ProjectedMeters projectedMetersForLatLng(const LatLng latLng) {
const double constrainedLatitude = std::fmin(std::fmax(latLng.latitude, -util::LATITUDE_MAX), util::LATITUDE_MAX);
const double m = 1 - 1e-15;
const double f = std::fmin(std::fmax(std::sin(util::DEG2RAD * constrainedLatitude), -m), m);
const double easting = util::EARTH_RADIUS_M * latLng.longitude * util::DEG2RAD;
const double northing = 0.5 * util::EARTH_RADIUS_M * std::log((1 + f) / (1 - f));
return ProjectedMeters(northing, easting);
}
static inline const LatLng latLngForProjectedMeters(const ProjectedMeters projectedMeters) {
double latitude = (2 * std::atan(std::exp(projectedMeters.northing / util::EARTH_RADIUS_M)) - (M_PI / 2)) * util::RAD2DEG;
double longitude = projectedMeters.easting * util::RAD2DEG / util::EARTH_RADIUS_M;
latitude = std::fmin(std::fmax(latitude, -util::LATITUDE_MAX), util::LATITUDE_MAX);
return LatLng(latitude, longitude);
}
};
}
#endif
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