only use half of rulers because earth is symmetric
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@ -25,20 +25,20 @@ namespace
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class CheapRulerContainer {
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public:
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CheapRulerContainer(const int number_of_rulers)
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: cheap_ruler_cache(number_of_rulers, mapbox::cheap_ruler::CheapRuler(0)), step(180. / number_of_rulers){
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: cheap_ruler_cache(number_of_rulers, mapbox::cheap_ruler::CheapRuler(0)), step(90.0 / number_of_rulers) {
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for (int n = 0; n < number_of_rulers; n++) {
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cheap_ruler_cache[n] = mapbox::cheap_ruler::CheapRuler(-90 + step * n, mapbox::cheap_ruler::CheapRuler::Meters);
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cheap_ruler_cache[n] = mapbox::cheap_ruler::CheapRuler(step * (n + 0.5), mapbox::cheap_ruler::CheapRuler::Meters);
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}
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};
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mapbox::cheap_ruler::CheapRuler& getRuler(const double lat) {
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return cheap_ruler_cache[std::min((int)std::round((lat + 90)/step), (int)cheap_ruler_cache.size() - 1)];
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return cheap_ruler_cache[std::min((int)std::floor(abs(lat)/step), (int)cheap_ruler_cache.size() - 1)];
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};
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private:
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std::vector<mapbox::cheap_ruler::CheapRuler> cheap_ruler_cache;
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const double step;
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};
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CheapRulerContainer cheap_ruler_container(3600);
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CheapRulerContainer cheap_ruler_container(1800);
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}
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// Does not project the coordinates!
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@ -65,7 +65,7 @@ double fccApproximateDistance(const Coordinate coordinate_1, const Coordinate co
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const auto lat1 = static_cast<double>(util::toFloating(coordinate_1.lat));
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const auto lon2 = static_cast<double>(util::toFloating(coordinate_2.lon));
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const auto lat2 = static_cast<double>(util::toFloating(coordinate_2.lat));
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return cheap_ruler_container.getRuler(lat1).distance({lon1, lat1}, {lon2, lat2});
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return cheap_ruler_container.getRuler(0.5*(lat1+lat2)).distance({lon1, lat1}, {lon2, lat2});
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}
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double haversineDistance(const Coordinate coordinate_1, const Coordinate coordinate_2)
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