// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2015-2020 Barend Gehrels, Amsterdam, the Netherlands.
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// This file was modified by Oracle on 2015-2020.
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// Modifications copyright (c) 2015-2020 Oracle and/or its affiliates.
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// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_DIRECTION_CODE_HPP
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#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_DIRECTION_CODE_HPP
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#include <type_traits>
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#include <boost/geometry/core/access.hpp>
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#include <boost/geometry/core/static_assert.hpp>
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#include <boost/geometry/arithmetic/infinite_line_functions.hpp>
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#include <boost/geometry/algorithms/detail/make/make.hpp>
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#include <boost/geometry/util/math.hpp>
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#include <boost/geometry/util/select_coordinate_type.hpp>
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#include <boost/geometry/util/normalize_spheroidal_coordinates.hpp>
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namespace boost { namespace geometry
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{
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#ifndef DOXYGEN_NO_DETAIL
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namespace detail
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{
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template <typename CSTag>
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struct direction_code_impl
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{
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BOOST_GEOMETRY_STATIC_ASSERT_FALSE(
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"Not implemented for this coordinate system.",
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CSTag);
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};
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template <>
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struct direction_code_impl<cartesian_tag>
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{
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template <typename Point1, typename Point2>
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static inline int apply(Point1 const& segment_a, Point1 const& segment_b,
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Point2 const& point)
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{
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typedef typename geometry::select_coordinate_type
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<
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Point1, Point2
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>::type calc_t;
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typedef model::infinite_line<calc_t> line_type;
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// Situation and construction of perpendicular line
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//
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// P1 a--------------->b P2
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// |
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// |
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// v
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//
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// P1 is located right of the (directional) perpendicular line
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// and therefore gets a negative side_value, and returns -1.
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// P2 is to the left of the perpendicular line and returns 1.
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// If the specified point is located on top of b, it returns 0.
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line_type const line
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= detail::make::make_perpendicular_line<calc_t>(segment_a,
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segment_b, segment_b);
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if (arithmetic::is_degenerate(line))
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{
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return 0;
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}
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calc_t const sv = arithmetic::side_value(line, point);
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return sv == 0 ? 0 : sv > 0 ? 1 : -1;
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}
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};
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template <>
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struct direction_code_impl<spherical_equatorial_tag>
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{
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template <typename Point1, typename Point2>
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static inline int apply(Point1 const& segment_a, Point1 const& segment_b,
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Point2 const& p)
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{
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typedef typename coordinate_type<Point1>::type coord1_t;
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typedef typename coordinate_type<Point2>::type coord2_t;
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typedef typename cs_angular_units<Point1>::type units_t;
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typedef typename cs_angular_units<Point2>::type units2_t;
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BOOST_GEOMETRY_STATIC_ASSERT(
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(std::is_same<units_t, units2_t>::value),
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"Not implemented for different units.",
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units_t, units2_t);
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typedef typename geometry::select_coordinate_type <Point1, Point2>::type calc_t;
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typedef math::detail::constants_on_spheroid<coord1_t, units_t> constants1;
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typedef math::detail::constants_on_spheroid<coord2_t, units_t> constants2;
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static coord1_t const pi_half1 = constants1::max_latitude();
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static coord2_t const pi_half2 = constants2::max_latitude();
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static calc_t const c0 = 0;
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coord1_t const a0 = geometry::get<0>(segment_a);
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coord1_t const a1 = geometry::get<1>(segment_a);
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coord1_t const b0 = geometry::get<0>(segment_b);
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coord1_t const b1 = geometry::get<1>(segment_b);
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coord2_t const p0 = geometry::get<0>(p);
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coord2_t const p1 = geometry::get<1>(p);
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if ( (math::equals(b0, a0) && math::equals(b1, a1))
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|| (math::equals(b0, p0) && math::equals(b1, p1)) )
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{
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return 0;
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}
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bool const is_a_pole = math::equals(pi_half1, math::abs(a1));
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bool const is_b_pole = math::equals(pi_half1, math::abs(b1));
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bool const is_p_pole = math::equals(pi_half2, math::abs(p1));
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if ( is_b_pole && ((is_a_pole && math::sign(b1) == math::sign(a1))
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|| (is_p_pole && math::sign(b1) == math::sign(p1))) )
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{
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return 0;
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}
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// NOTE: as opposed to the implementation for cartesian CS
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// here point b is the origin
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calc_t const dlon1 = math::longitude_distance_signed<units_t, calc_t>(b0, a0);
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calc_t const dlon2 = math::longitude_distance_signed<units_t, calc_t>(b0, p0);
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bool is_antilon1 = false, is_antilon2 = false;
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calc_t const dlat1 = latitude_distance_signed<units_t, calc_t>(b1, a1, dlon1, is_antilon1);
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calc_t const dlat2 = latitude_distance_signed<units_t, calc_t>(b1, p1, dlon2, is_antilon2);
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calc_t mx = is_a_pole || is_b_pole || is_p_pole ?
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c0 :
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(std::min)(is_antilon1 ? c0 : math::abs(dlon1),
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is_antilon2 ? c0 : math::abs(dlon2));
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calc_t my = (std::min)(math::abs(dlat1),
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math::abs(dlat2));
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int s1 = 0, s2 = 0;
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if (mx >= my)
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{
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s1 = dlon1 > 0 ? 1 : -1;
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s2 = dlon2 > 0 ? 1 : -1;
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}
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else
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{
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s1 = dlat1 > 0 ? 1 : -1;
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s2 = dlat2 > 0 ? 1 : -1;
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}
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return s1 == s2 ? -1 : 1;
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}
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template <typename Units, typename T>
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static inline T latitude_distance_signed(T const& lat1, T const& lat2, T const& lon_ds, bool & is_antilon)
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{
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typedef math::detail::constants_on_spheroid<T, Units> constants;
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static T const pi = constants::half_period();
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static T const c0 = 0;
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T res = lat2 - lat1;
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is_antilon = math::equals(math::abs(lon_ds), pi);
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if (is_antilon)
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{
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res = lat2 + lat1;
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if (res >= c0)
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res = pi - res;
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else
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res = -pi - res;
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}
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return res;
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}
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};
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template <>
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struct direction_code_impl<spherical_polar_tag>
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{
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template <typename Point1, typename Point2>
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static inline int apply(Point1 segment_a, Point1 segment_b,
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Point2 p)
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{
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typedef math::detail::constants_on_spheroid
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<
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typename coordinate_type<Point1>::type,
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typename cs_angular_units<Point1>::type
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> constants1;
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typedef math::detail::constants_on_spheroid
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<
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typename coordinate_type<Point2>::type,
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typename cs_angular_units<Point2>::type
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> constants2;
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geometry::set<1>(segment_a,
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constants1::max_latitude() - geometry::get<1>(segment_a));
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geometry::set<1>(segment_b,
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constants1::max_latitude() - geometry::get<1>(segment_b));
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geometry::set<1>(p,
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constants2::max_latitude() - geometry::get<1>(p));
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return direction_code_impl
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<
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spherical_equatorial_tag
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>::apply(segment_a, segment_b, p);
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}
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};
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// if spherical_tag is passed then pick cs_tag based on Point1 type
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// with spherical_equatorial_tag as the default
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template <>
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struct direction_code_impl<spherical_tag>
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{
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template <typename Point1, typename Point2>
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static inline int apply(Point1 segment_a, Point1 segment_b,
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Point2 p)
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{
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return direction_code_impl
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<
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std::conditional_t
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<
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std::is_same
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<
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typename geometry::cs_tag<Point1>::type,
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spherical_polar_tag
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>::value,
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spherical_polar_tag,
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spherical_equatorial_tag
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>
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>::apply(segment_a, segment_b, p);
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}
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};
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template <>
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struct direction_code_impl<geographic_tag>
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: direction_code_impl<spherical_equatorial_tag>
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{};
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// Gives sense of direction for point p, collinear w.r.t. segment (a,b)
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// Returns -1 if p goes backward w.r.t (a,b), so goes from b in direction of a
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// Returns 1 if p goes forward, so extends (a,b)
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// Returns 0 if p is equal with b, or if (a,b) is degenerate
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// Note that it does not do any collinearity test, that should be done before
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template <typename CSTag, typename Point1, typename Point2>
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inline int direction_code(Point1 const& segment_a, Point1 const& segment_b,
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Point2 const& p)
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{
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return direction_code_impl<CSTag>::apply(segment_a, segment_b, p);
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}
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} // namespace detail
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#endif //DOXYGEN_NO_DETAIL
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_DIRECTION_CODE_HPP
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