boost/geometry/algorithms/detail/buffer/line_line_intersection.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2012-2019 Barend Gehrels, Amsterdam, the Netherlands.
   4
   5 // Use, modification and distribution is subject to the Boost Software License,
   6 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   7 // http://www.boost.org/LICENSE_1_0.txt)
   8
   9 #ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_BUFFER_LINE_LINE_INTERSECTION_HPP
  10 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_BUFFER_LINE_LINE_INTERSECTION_HPP
  11
  12
  13 #include <boost/geometry/arithmetic/infinite_line_functions.hpp>
  14 #include <boost/geometry/algorithms/detail/make/make.hpp>
  15 #include <boost/geometry/strategies/buffer.hpp>
  16
  17 namespace boost { namespace geometry
  18 {
  19
  20
  21 #ifndef DOXYGEN_NO_DETAIL
  22 namespace detail { namespace buffer
  23 {
  24
  25 // TODO: it might once be changed this to proper strategy
  26 struct line_line_intersection
  27 {
  28     template <typename Point>
  29     static inline strategy::buffer::join_selector
  30     apply(Point const& pi, Point const& pj,
  31           Point const& qi, Point const& qj,
  32           Point& ip)
  33     {
  34         typedef typename coordinate_type<Point>::type ct;
  35         typedef model::infinite_line<ct> line_type;
  36
  37         line_type const p = detail::make::make_infinite_line<ct>(pi, pj);
  38         line_type const q = detail::make::make_infinite_line<ct>(qi, qj);
  39
  40         if (arithmetic::intersection_point(p, q, ip))
  41         {
  42             return strategy::buffer::join_convex;
  43         }
  44
  45         // The lines do not intersect.
  46         // Distinguish between continuing lines (having a similar direction)
  47         // and spikes (having the opposite direction).
  48         return arithmetic::similar_direction(p, q)
  49             ? strategy::buffer::join_continue
  50             : strategy::buffer::join_spike
  51             ;
  52     }
  53 };
  54
  55
  56 }} // namespace detail::buffer
  57 #endif // DOXYGEN_NO_DETAIL
  58
  59
  60 }} // namespace boost::geometry
  61
  62
  63 #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_BUFFER_LINE_LINE_INTERSECTION_HPP