ceph/src/boost/libs/geometry/include/boost/geometry/algorithms/detail/distance/segment_to_segment.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2014, Oracle and/or its affiliates.
   4
   5 // Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
   6
   7 // Licensed under the Boost Software License version 1.0.
   8 // http://www.boost.org/users/license.html
   9
  10 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_DISTANCE_SEGMENT_TO_SEGMENT_HPP
  11 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_DISTANCE_SEGMENT_TO_SEGMENT_HPP
  12
  13 #include <algorithm>
  14 #include <iterator>
  15
  16 #include <boost/core/addressof.hpp>
  17
  18 #include <boost/geometry/core/point_type.hpp>
  19 #include <boost/geometry/core/tags.hpp>
  20
  21 #include <boost/geometry/util/condition.hpp>
  22
  23 #include <boost/geometry/strategies/distance.hpp>
  24 #include <boost/geometry/strategies/tags.hpp>
  25
  26 #include <boost/geometry/algorithms/assign.hpp>
  27 #include <boost/geometry/algorithms/intersects.hpp>
  28
  29 #include <boost/geometry/algorithms/detail/distance/is_comparable.hpp>
  30
  31 #include <boost/geometry/algorithms/dispatch/distance.hpp>
  32
  33
  34 namespace boost { namespace geometry
  35 {
  36
  37
  38 #ifndef DOXYGEN_NO_DETAIL
  39 namespace detail { namespace distance
  40 {
  41
  42
  43
  44 // compute segment-segment distance
  45 template<typename Segment1, typename Segment2, typename Strategy>
  46 class segment_to_segment
  47 {
  48 private:
  49     typedef typename strategy::distance::services::comparable_type
  50         <
  51             Strategy
  52         >::type comparable_strategy;
  53
  54     typedef typename strategy::distance::services::return_type
  55         <
  56             comparable_strategy,
  57             typename point_type<Segment1>::type,
  58             typename point_type<Segment2>::type
  59         >::type comparable_return_type;
  60
  61 public:
  62     typedef typename strategy::distance::services::return_type
  63         <
  64             Strategy,
  65             typename point_type<Segment1>::type,
  66             typename point_type<Segment2>::type
  67         >::type return_type;
  68
  69     static inline return_type
  70     apply(Segment1 const& segment1, Segment2 const& segment2,
  71           Strategy const& strategy)
  72     {
  73         if (geometry::intersects(segment1, segment2))
  74         {
  75             return 0;
  76         }
  77
  78         typename point_type<Segment1>::type p[2];
  79         detail::assign_point_from_index<0>(segment1, p[0]);
  80         detail::assign_point_from_index<1>(segment1, p[1]);
  81
  82         typename point_type<Segment2>::type q[2];
  83         detail::assign_point_from_index<0>(segment2, q[0]);
  84         detail::assign_point_from_index<1>(segment2, q[1]);
  85
  86         comparable_strategy cstrategy =
  87             strategy::distance::services::get_comparable
  88                 <
  89                     Strategy
  90                 >::apply(strategy);
  91
  92         comparable_return_type d[4];
  93         d[0] = cstrategy.apply(q[0], p[0], p[1]);
  94         d[1] = cstrategy.apply(q[1], p[0], p[1]);
  95         d[2] = cstrategy.apply(p[0], q[0], q[1]);
  96         d[3] = cstrategy.apply(p[1], q[0], q[1]);
  97
  98         std::size_t imin = std::distance(boost::addressof(d[0]),
  99                                          std::min_element(d, d + 4));
 100
 101         if (BOOST_GEOMETRY_CONDITION(is_comparable<Strategy>::value))
 102         {
 103             return d[imin];
 104         }
 105
 106         switch (imin)
 107         {
 108         case 0:
 109             return strategy.apply(q[0], p[0], p[1]);
 110         case 1:
 111             return strategy.apply(q[1], p[0], p[1]);
 112         case 2:
 113             return strategy.apply(p[0], q[0], q[1]);
 114         default:
 115             return strategy.apply(p[1], q[0], q[1]);
 116         }
 117     }
 118 };
 119
 120
 121
 122
 123 }} // namespace detail::distance
 124 #endif // DOXYGEN_NO_DETAIL
 125
 126
 127 #ifndef DOXYGEN_NO_DISPATCH
 128 namespace dispatch
 129 {
 130
 131
 132
 133 // segment-segment
 134 template <typename Segment1, typename Segment2, typename Strategy>
 135 struct distance
 136     <
 137         Segment1, Segment2, Strategy, segment_tag, segment_tag,
 138         strategy_tag_distance_point_segment, false
 139     >
 140     : detail::distance::segment_to_segment<Segment1, Segment2, Strategy>
 141 {};
 142
 143
 144
 145 } // namespace dispatch
 146 #endif // DOXYGEN_NO_DISPATCH
 147
 148
 149 }} // namespace boost::geometry
 150
 151
 152 #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_DISTANCE_SEGMENT_TO_SEGMENT_HPP