longitude_range_normalizer.h

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#ifndef SQL_GIS_LONGITUDE_RANGE_NORMALIZER_H_INCLUDED
#define SQL_GIS_LONGITUDE_RANGE_NORMALIZER_H_INCLUDED
 
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/// @file
///
/// Implements a longitude normalizer that converts longitude coordinates
/// outside the range such that geometries wrap correctly across
/// the 180/-180 boundary on the globe.
 
#include <cmath>  // M_PI
 
#include "sql/dd/types/spatial_reference_system.h"  // dd::Spatial_reference_system
#include "sql/gis/geometry_visitor.h"
 
namespace gis {
 
class Longitude_range_normalizer : public Nop_visitor {
 private:
  const dd::Spatial_reference_system *m_srs;
 
 public:
  /// Construct a new longitude range normalizer.
  ///
  /// @param srs The spatial reference system of the geometry.
  explicit Longitude_range_normalizer(const dd::Spatial_reference_system *srs)
      : m_srs(srs) {}
 
  using Nop_visitor::visit;
  bool visit(Point *pt) override {
    double lon = pt->x() - m_srs->prime_meridian() * m_srs->angular_unit();
    if (!m_srs->positive_east()) lon *= -1.0;
    if (lon <= -M_PI) {
      // Longitude -180 or less, so we add 360 (2*pi): e.g. -182 + 360 = 178
      pt->x(lon + 2.0 * M_PI);
    } else if (lon > M_PI) {
      // Longitude over 180, so we subtract 360 (2*pi): e.g. 181 - 360 = -179
      pt->x(lon - 2.0 * M_PI);
    }
    return false;
  }
};
 
}  // namespace gis
 
#endif  // SQL_GIS_LONGITUDE_RANGE_NORMALIZER_H_INCLUDED