git.sesse.net Git - casparcg/blob - dependencies/boost/boost/geometry/strategies/cartesian/centroid_weighted_length.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2009-2011 Mateusz Loskot, London, UK.
   4 // Copyright (c) 2009-2011 Barend Gehrels, Amsterdam, the Netherlands.
   5
   6 // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
   7 // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
   8
   9 // Use, modification and distribution is subject to the Boost Software License,
  10 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  11 // http://www.boost.org/LICENSE_1_0.txt)
  12
  13 #ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_WEIGHTED_LENGTH_HPP
  14 #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_WEIGHTED_LENGTH_HPP
  15
  16 #include <boost/geometry/algorithms/distance.hpp>
  17 #include <boost/geometry/arithmetic/arithmetic.hpp>
  18 #include <boost/geometry/util/select_most_precise.hpp>
  19 #include <boost/geometry/strategies/centroid.hpp>
  20 #include <boost/geometry/strategies/default_distance_result.hpp>
  21
  22 // Helper geometry
  23 #include <boost/geometry/geometries/point.hpp>
  24
  25
  26 namespace boost { namespace geometry
  27 {
  28
  29 namespace strategy { namespace centroid
  30 {
  31
  32 namespace detail
  33 {
  34
  35 template <typename Type, std::size_t DimensionCount>
  36 struct weighted_length_sums
  37 {
  38     typedef typename geometry::model::point
  39         <
  40             Type, DimensionCount,
  41             cs::cartesian
  42         > work_point;
  43
  44     Type length;
  45     work_point average_sum;
  46
  47     inline weighted_length_sums()
  48         : length(Type())
  49     {
  50         geometry::assign_zero(average_sum);
  51     }
  52 };
  53 }
  54
  55 template
  56 <
  57     typename Point,
  58     typename PointOfSegment = Point
  59 >
  60 class weighted_length
  61 {
  62 private :
  63     typedef typename select_most_precise
  64         <
  65             typename default_distance_result<Point>::type,
  66             typename default_distance_result<PointOfSegment>::type
  67         >::type distance_type;
  68
  69 public :
  70     typedef detail::weighted_length_sums
  71         <
  72             distance_type,
  73             geometry::dimension<Point>::type::value
  74         > state_type;
  75
  76     static inline void apply(PointOfSegment const& p1,
  77             PointOfSegment const& p2, state_type& state)
  78     {
  79         distance_type const d = geometry::distance(p1, p2);
  80         state.length += d;
  81
  82         typename state_type::work_point weighted_median;
  83         geometry::assign_zero(weighted_median);
  84         geometry::add_point(weighted_median, p1);
  85         geometry::add_point(weighted_median, p2);
  86         geometry::multiply_value(weighted_median, d/2);
  87         geometry::add_point(state.average_sum, weighted_median);
  88     }
  89
  90     static inline bool result(state_type const& state, Point& centroid)
  91     {
  92         distance_type const zero = distance_type();
  93         if (! geometry::math::equals(state.length, zero))
  94         {
  95             assign_zero(centroid);
  96             add_point(centroid, state.average_sum);
  97             divide_value(centroid, state.length);
  98             return true;
  99         }
 100
 101         return false;
 102     }
 103
 104 };
 105
 106 #ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
 107
 108 namespace services
 109 {
 110
 111
 112 // Register this strategy for linear geometries, in all dimensions
 113
 114 template <std::size_t N, typename Point, typename Geometry>
 115 struct default_strategy
 116 <
 117     cartesian_tag,
 118     linear_tag,
 119     N,
 120     Point,
 121     Geometry
 122 >
 123 {
 124     typedef weighted_length
 125         <
 126             Point,
 127             typename point_type<Geometry>::type
 128         > type;
 129 };
 130
 131
 132 } // namespace services
 133
 134
 135 #endif // DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
 136
 137
 138 }} // namespace strategy::centroid
 139
 140
 141 }} // namespace boost::geometry
 142
 143
 144 #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_CENTROID_WEIGHTED_LENGTH_HPP