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// Boost.Geometry
// Copyright (c) 2017 Oracle and/or its affiliates.
// Contributed and/or modified by Vissarion Fysikopoulos, on behalf of Oracle
// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_GEOMETRY_FORMULAS_MERIDIAN_SEGMENT_HPP
#define BOOST_GEOMETRY_FORMULAS_MERIDIAN_SEGMENT_HPP
#include <boost/math/constants/constants.hpp>
#include <boost/geometry/core/radius.hpp>
#include <boost/geometry/srs/srs.hpp>
#include <boost/geometry/util/condition.hpp>
#include <boost/geometry/util/math.hpp>
#include <boost/geometry/util/normalize_spheroidal_coordinates.hpp>
namespace boost { namespace geometry { namespace formula
{
/*!
\brief Test if a segment is meridian or not.
*/
class meridian_segment
{
public :
enum SegmentType {NonMeridian, MeridianCrossingPole, MeridianNotCrossingPole};
template <typename T>
static inline SegmentType is_meridian(T lon1, T lat1, T lon2, T lat2)
{
SegmentType res = NonMeridian;
T diff = geometry::math::longitude_distance_signed<geometry::radian>(lon1, lon2);
if ( meridian_not_crossing_pole(lat1, lat2, diff) )
{
res = MeridianNotCrossingPole;
}
else if ( meridian_crossing_pole(diff) )
{
res = MeridianCrossingPole;
}
return res;
}
template <typename T>
static bool meridian_not_crossing_pole(T lat1, T lat2, T diff)
{
T half_pi = math::half_pi<T>();
return math::equals(diff, T(0)) ||
(math::equals(lat2, half_pi) && math::equals(lat1, -half_pi));
}
template <typename T>
static bool meridian_crossing_pole(T diff)
{
return math::equals(math::abs(diff), math::pi<T>());
}
};
}}} // namespace boost::geometry::formula
#endif //BOOST_GEOMETRY_FORMULAS_MERIDIAN_SEGMENT_HPP
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