78ec33320f
some functions defined in <cmath>, as well as std::to_string aren't available on GNU's STL for some platforms, e.g. Android
66 lines
2.2 KiB
C++
66 lines
2.2 KiB
C++
#ifndef MBGL_UTIL_PROJECTION
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#define MBGL_UTIL_PROJECTION
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#include <mbgl/util/constants.hpp>
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#include <mbgl/util/geo.hpp>
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#include <cmath>
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namespace mbgl {
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class Projection {
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public:
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static inline void getWorldBoundsMeters(ProjectedMeters &sw, ProjectedMeters &ne) {
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const double d = util::EARTH_RADIUS_M * M_PI;
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sw.easting = -d;
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sw.northing = -d;
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ne.easting = d;
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ne.northing = d;
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}
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static inline void getWorldBoundsLatLng(LatLng &sw, LatLng &ne) {
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ProjectedMeters projectedMetersSW = ProjectedMeters();
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ProjectedMeters projectedMetersNE = ProjectedMeters();
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getWorldBoundsMeters(projectedMetersSW, projectedMetersNE);
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sw = latLngForProjectedMeters(projectedMetersSW);
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ne = latLngForProjectedMeters(projectedMetersNE);
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}
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static inline double getMetersPerPixelAtLatitude(const double lat, const double zoom) {
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const double mapPixelWidthAtZoom = std::pow(2.0, zoom) * util::tileSize;
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const double constrainedLatitude = ::fmin(::fmax(lat, -util::LATITUDE_MAX), util::LATITUDE_MAX);
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return std::cos(constrainedLatitude * util::DEG2RAD) * util::M2PI * util::EARTH_RADIUS_M / mapPixelWidthAtZoom;
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}
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static inline const ProjectedMeters projectedMetersForLatLng(const LatLng latLng) {
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const double constrainedLatitude = ::fmin(::fmax(latLng.latitude, -util::LATITUDE_MAX), util::LATITUDE_MAX);
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const double m = 1 - 1e-15;
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const double f = ::fmin(::fmax(std::sin(util::DEG2RAD * constrainedLatitude), -m), m);
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const double easting = util::EARTH_RADIUS_M * latLng.longitude * util::DEG2RAD;
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const double northing = 0.5 * util::EARTH_RADIUS_M * std::log((1 + f) / (1 - f));
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return ProjectedMeters(northing, easting);
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}
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static inline const LatLng latLngForProjectedMeters(const ProjectedMeters projectedMeters) {
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double latitude = (2 * std::atan(std::exp(projectedMeters.northing / util::EARTH_RADIUS_M)) - (M_PI / 2)) * util::RAD2DEG;
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double longitude = projectedMeters.easting * util::RAD2DEG / util::EARTH_RADIUS_M;
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latitude = ::fmin(::fmax(latitude, -util::LATITUDE_MAX), util::LATITUDE_MAX);
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return LatLng(latitude, longitude);
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}
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};
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}
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#endif
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