95 lines
3.0 KiB
C++
95 lines
3.0 KiB
C++
/**
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* \file CassiniSoldner.cpp
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* \brief Implementation for GeographicLib::CassiniSoldner class
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*
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* Copyright (c) Charles Karney (2009-2022) <charles@karney.com> and licensed
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* under the MIT/X11 License. For more information, see
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* https://geographiclib.sourceforge.io/
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**********************************************************************/
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#include <GeographicLib/CassiniSoldner.hpp>
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#if defined(_MSC_VER)
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// Squelch warnings about enum-float expressions
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# pragma warning (disable: 5055)
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#endif
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namespace GeographicLib {
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using namespace std;
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CassiniSoldner::CassiniSoldner(const Geodesic& earth)
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: _earth(earth) {}
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CassiniSoldner::CassiniSoldner(real lat0, real lon0, const Geodesic& earth)
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: _earth(earth)
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{ Reset(lat0, lon0); }
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void CassiniSoldner::Reset(real lat0, real lon0) {
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_meridian = _earth.Line(lat0, lon0, real(0),
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Geodesic::LATITUDE | Geodesic::LONGITUDE |
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Geodesic::DISTANCE | Geodesic::DISTANCE_IN |
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Geodesic::AZIMUTH);
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real f = _earth.Flattening();
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Math::sincosd(LatitudeOrigin(), _sbet0, _cbet0);
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_sbet0 *= (1 - f);
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Math::norm(_sbet0, _cbet0);
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}
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void CassiniSoldner::Forward(real lat, real lon, real& x, real& y,
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real& azi, real& rk) const {
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if (!Init())
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return;
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real dlon = Math::AngDiff(LongitudeOrigin(), lon);
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real sig12, s12, azi1, azi2;
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sig12 = _earth.Inverse(lat, -fabs(dlon), lat, fabs(dlon), s12, azi1, azi2);
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sig12 *= real(0.5);
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s12 *= real(0.5);
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if (s12 == 0) {
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real da = Math::AngDiff(azi1, azi2)/2;
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if (fabs(dlon) <= Math::qd) {
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azi1 = Math::qd - da;
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azi2 = Math::qd + da;
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} else {
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azi1 = -Math::qd - da;
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azi2 = -Math::qd + da;
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}
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}
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if (signbit(dlon)) {
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azi2 = azi1;
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s12 = -s12;
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sig12 = -sig12;
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}
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x = s12;
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azi = Math::AngNormalize(azi2);
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GeodesicLine perp(_earth.Line(lat, dlon, azi, Geodesic::GEODESICSCALE));
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real t;
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perp.GenPosition(true, -sig12,
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Geodesic::GEODESICSCALE,
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t, t, t, t, t, t, rk, t);
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real salp0, calp0;
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Math::sincosd(perp.EquatorialAzimuth(), salp0, calp0);
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real
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sbet1 = lat >=0 ? calp0 : -calp0,
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cbet1 = fabs(dlon) <= Math::qd ? fabs(salp0) : -fabs(salp0),
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sbet01 = sbet1 * _cbet0 - cbet1 * _sbet0,
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cbet01 = cbet1 * _cbet0 + sbet1 * _sbet0,
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sig01 = atan2(sbet01, cbet01) / Math::degree();
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_meridian.GenPosition(true, sig01,
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Geodesic::DISTANCE,
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t, t, t, y, t, t, t, t);
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}
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void CassiniSoldner::Reverse(real x, real y, real& lat, real& lon,
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real& azi, real& rk) const {
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if (!Init())
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return;
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real lat1, lon1;
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real azi0, t;
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_meridian.Position(y, lat1, lon1, azi0);
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_earth.Direct(lat1, lon1, azi0 + Math::qd, x, lat, lon, azi, rk, t);
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}
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} // namespace GeographicLib
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