projects / ceph.git / blame
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| 7c673cae FG |
1 | // Boost.Geometry (aka GGL, Generic Geometry Library) |
| 2 | ||
| 3 | // Copyright (c) 2007-2012 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_OVERLAY_GET_RELATIVE_ORDER_HPP | |
| 10 | #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RELATIVE_ORDER_HPP | |
| 11 | ||
| 12 | ||
| 13 | #include <boost/geometry/strategies/intersection_strategies.hpp> | |
| 14 | ||
| 15 | ||
| 16 | namespace boost { namespace geometry | |
| 17 | { | |
| 18 | ||
| 19 | ||
| 20 | #ifndef DOXYGEN_NO_DETAIL | |
| 21 | namespace detail { namespace overlay | |
| 22 | { | |
| 23 | ||
| 24 | ||
| 25 | /*! | |
| 26 | \brief Get relative order | |
| 27 | \details Can indicate which of two segments R and S, | |
| 28 | both crossing a common segment P, comes first. | |
| 29 | If the two segments cross P very close (e.g. in a spike), | |
| 30 | the distance between the intersection points can be zero, | |
| 31 | but we still need to know which comes first. | |
| 32 | Therefore, it is useful that using sides we are able to discover this. | |
| 33 | */ | |
| 34 | template <typename Point1> | |
| 35 | struct get_relative_order | |
| 36 | { | |
| 37 | typedef typename strategy::side::services::default_strategy | |
| 38 | < | |
| 39 | typename cs_tag<Point1>::type | |
| 40 | >::type strategy; | |
| 41 | ||
| 42 | template <typename Point> | |
| 43 | static inline int value_via_product(Point const& ti, Point const& tj, | |
| 44 | Point const& ui, Point const& uj, int factor) | |
| 45 | { | |
| 46 | int const side_ti_u = strategy::apply(ti, tj, ui); | |
| 47 | int const side_tj_u = strategy::apply(ti, tj, uj); | |
| 48 | ||
| 49 | #ifdef BOOST_GEOMETRY_DEBUG_RELATIVE_ORDER | |
| 50 | std::cout << (factor == 1 ? " r//s " : " s//r ") | |
| 51 | << side_ti_u << " / " << side_tj_u; | |
| 52 | #endif | |
| 53 | ||
| 54 | return side_ti_u * side_tj_u >= 0 | |
| 55 | ? factor * (side_ti_u != 0 ? side_ti_u : side_tj_u) | |
| 56 | : 0; | |
| 57 | } | |
| 58 | ||
| 59 | ||
| 60 | static inline int apply( | |
| 61 | Point1 const& pi, Point1 const& pj, | |
| 62 | Point1 const& ri, Point1 const& rj, | |
| 63 | Point1 const& si, Point1 const& sj) | |
| 64 | { | |
| 65 | int const side_ri_p = strategy::apply(pi, pj, ri); | |
| 66 | int const side_si_p = strategy::apply(pi, pj, si); | |
| 67 | ||
| 68 | #ifdef BOOST_GEOMETRY_DEBUG_RELATIVE_ORDER | |
| 69 | int const side_rj_p = strategy::apply(pi, pj, rj); | |
| 70 | int const side_sj_p = strategy::apply(pi, pj, sj); | |
| 71 | std::cout << "r//p: " << side_ri_p << " / " << side_rj_p; | |
| 72 | std::cout << " s//p: " << side_si_p << " / " << side_sj_p; | |
| 73 | #endif | |
| 74 | ||
| 75 | int value = value_via_product(si, sj, ri, rj, 1); | |
| 76 | if (value == 0) | |
| 77 | { | |
| 78 | value = value_via_product(ri, rj, si, sj, -1); | |
| 79 | } | |
| 80 | ||
| 81 | int const order = side_ri_p * side_ri_p * side_si_p * value; | |
| 82 | ||
| 83 | #ifdef BOOST_GEOMETRY_DEBUG_RELATIVE_ORDER | |
| 84 | std::cout | |
| 85 | << " o: " << order | |
| 86 | << std::endl << std::endl; | |
| 87 | #endif | |
| 88 | ||
| 89 | return order; | |
| 90 | } | |
| 91 | }; | |
| 92 | ||
| 93 | ||
| 94 | }} // namespace detail::overlay | |
| 95 | #endif //DOXYGEN_NO_DETAIL | |
| 96 | ||
| 97 | ||
| 98 | }} // namespace boost::geometry | |
| 99 | ||
| 100 | ||
| 101 | #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_GET_RELATIVE_ORDER_HPP |