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- #ifndef BOOST_GEOMETRY_PROJECTIONS_GNOM_HPP
- #define BOOST_GEOMETRY_PROJECTIONS_GNOM_HPP
- #include <boost/config.hpp>
- #include <boost/geometry/util/math.hpp>
- #include <boost/math/special_functions/hypot.hpp>
- #include <boost/geometry/srs/projections/impl/base_static.hpp>
- #include <boost/geometry/srs/projections/impl/base_dynamic.hpp>
- #include <boost/geometry/srs/projections/impl/projects.hpp>
- #include <boost/geometry/srs/projections/impl/factory_entry.hpp>
- namespace boost { namespace geometry
- {
- namespace projections
- {
- #ifndef DOXYGEN_NO_DETAIL
- namespace detail { namespace gnom
- {
- static const double epsilon10 = 1.e-10;
- enum mode_type {
- n_pole = 0,
- s_pole = 1,
- equit = 2,
- obliq = 3
- };
- template <typename T>
- struct par_gnom
- {
- T sinph0;
- T cosph0;
- mode_type mode;
- };
- template <typename T, typename Parameters>
- struct base_gnom_spheroid
- {
- par_gnom<T> m_proj_parm;
-
-
- inline void fwd(Parameters const& , T const& lp_lon, T const& lp_lat, T& xy_x, T& xy_y) const
- {
- T coslam, cosphi, sinphi;
- sinphi = sin(lp_lat);
- cosphi = cos(lp_lat);
- coslam = cos(lp_lon);
- switch (this->m_proj_parm.mode) {
- case equit:
- xy_y = cosphi * coslam;
- break;
- case obliq:
- xy_y = this->m_proj_parm.sinph0 * sinphi + this->m_proj_parm.cosph0 * cosphi * coslam;
- break;
- case s_pole:
- xy_y = - sinphi;
- break;
- case n_pole:
- xy_y = sinphi;
- break;
- }
- if (xy_y <= epsilon10) {
- BOOST_THROW_EXCEPTION( projection_exception(error_tolerance_condition) );
- }
- xy_x = (xy_y = 1. / xy_y) * cosphi * sin(lp_lon);
- switch (this->m_proj_parm.mode) {
- case equit:
- xy_y *= sinphi;
- break;
- case obliq:
- xy_y *= this->m_proj_parm.cosph0 * sinphi - this->m_proj_parm.sinph0 * cosphi * coslam;
- break;
- case n_pole:
- coslam = - coslam;
- BOOST_FALLTHROUGH;
- case s_pole:
- xy_y *= cosphi * coslam;
- break;
- }
- }
-
-
- inline void inv(Parameters const& par, T xy_x, T xy_y, T& lp_lon, T& lp_lat) const
- {
- static const T half_pi = detail::half_pi<T>();
- T rh, cosz, sinz;
- rh = boost::math::hypot(xy_x, xy_y);
- sinz = sin(lp_lat = atan(rh));
- cosz = sqrt(1. - sinz * sinz);
- if (fabs(rh) <= epsilon10) {
- lp_lat = par.phi0;
- lp_lon = 0.;
- } else {
- switch (this->m_proj_parm.mode) {
- case obliq:
- lp_lat = cosz * this->m_proj_parm.sinph0 + xy_y * sinz * this->m_proj_parm.cosph0 / rh;
- if (fabs(lp_lat) >= 1.)
- lp_lat = lp_lat > 0. ? half_pi : -half_pi;
- else
- lp_lat = asin(lp_lat);
- xy_y = (cosz - this->m_proj_parm.sinph0 * sin(lp_lat)) * rh;
- xy_x *= sinz * this->m_proj_parm.cosph0;
- break;
- case equit:
- lp_lat = xy_y * sinz / rh;
- if (fabs(lp_lat) >= 1.)
- lp_lat = lp_lat > 0. ? half_pi : -half_pi;
- else
- lp_lat = asin(lp_lat);
- xy_y = cosz * rh;
- xy_x *= sinz;
- break;
- case s_pole:
- lp_lat -= half_pi;
- break;
- case n_pole:
- lp_lat = half_pi - lp_lat;
- xy_y = -xy_y;
- break;
- }
- lp_lon = atan2(xy_x, xy_y);
- }
- }
- static inline std::string get_name()
- {
- return "gnom_spheroid";
- }
- };
-
- template <typename Parameters, typename T>
- inline void setup_gnom(Parameters& par, par_gnom<T>& proj_parm)
- {
- static const T half_pi = detail::half_pi<T>();
- if (fabs(fabs(par.phi0) - half_pi) < epsilon10) {
- proj_parm.mode = par.phi0 < 0. ? s_pole : n_pole;
- } else if (fabs(par.phi0) < epsilon10) {
- proj_parm.mode = equit;
- } else {
- proj_parm.mode = obliq;
- proj_parm.sinph0 = sin(par.phi0);
- proj_parm.cosph0 = cos(par.phi0);
- }
- par.es = 0.;
- }
- }}
- #endif
-
- template <typename T, typename Parameters>
- struct gnom_spheroid : public detail::gnom::base_gnom_spheroid<T, Parameters>
- {
- template <typename Params>
- inline gnom_spheroid(Params const& , Parameters & par)
- {
- detail::gnom::setup_gnom(par, this->m_proj_parm);
- }
- };
- #ifndef DOXYGEN_NO_DETAIL
- namespace detail
- {
-
- BOOST_GEOMETRY_PROJECTIONS_DETAIL_STATIC_PROJECTION_FI(srs::spar::proj_gnom, gnom_spheroid)
-
- BOOST_GEOMETRY_PROJECTIONS_DETAIL_FACTORY_ENTRY_FI(gnom_entry, gnom_spheroid)
- BOOST_GEOMETRY_PROJECTIONS_DETAIL_FACTORY_INIT_BEGIN(gnom_init)
- {
- BOOST_GEOMETRY_PROJECTIONS_DETAIL_FACTORY_INIT_ENTRY(gnom, gnom_entry);
- }
- }
- #endif
- }
- }}
- #endif
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