ceph/src/boost/libs/geometry/include/boost/geometry/strategies/cartesian/point_in_poly_crossings_multiply.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
   4 // Copyright (c) 2008-2012 Bruno Lalande, Paris, France.
   5 // Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
   6
   7 // Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
   8 // (geolib/GGL), copyright (c) 1995-2010 Geodan, Amsterdam, the Netherlands.
   9
  10 // Use, modification and distribution is subject to the Boost Software License,
  11 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  12 // http://www.boost.org/LICENSE_1_0.txt)
  13
  14 #ifndef BOOST_GEOMETRY_STRATEGIES_CARTESIAN_POINT_IN_POLY_CROSSINGS_MULTIPLY_HPP
  15 #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_POINT_IN_POLY_CROSSINGS_MULTIPLY_HPP
  16
  17
  18 #include <boost/geometry/core/coordinate_type.hpp>
  19 #include <boost/geometry/util/select_calculation_type.hpp>
  20
  21
  22 namespace boost { namespace geometry
  23 {
  24
  25 namespace strategy { namespace within
  26 {
  27
  28 /*!
  29 \brief Within detection using cross counting,
  30 \ingroup strategies
  31 \tparam Point \tparam_point
  32 \tparam PointOfSegment \tparam_segment_point
  33 \tparam CalculationType \tparam_calculation
  34 \see http://tog.acm.org/resources/GraphicsGems/gemsiv/ptpoly_haines/ptinpoly.c
  35 \note Does NOT work correctly for point ON border
  36 \qbk{
  37 [heading See also]
  38 [link geometry.reference.algorithms.within.within_3_with_strategy within (with strategy)]
  39 }
  40  */
  41
  42 template
  43 <
  44     typename Point,
  45     typename PointOfSegment = Point,
  46     typename CalculationType = void
  47 >
  48 class crossings_multiply
  49 {
  50     typedef typename select_calculation_type
  51         <
  52             Point,
  53             PointOfSegment,
  54             CalculationType
  55         >::type calculation_type;
  56
  57     class flags
  58     {
  59         bool inside_flag;
  60         bool first;
  61         bool yflag0;
  62
  63     public :
  64
  65         friend class crossings_multiply;
  66
  67         inline flags()
  68             : inside_flag(false)
  69             , first(true)
  70             , yflag0(false)
  71         {}
  72     };
  73
  74 public :
  75
  76     typedef Point point_type;
  77     typedef PointOfSegment segment_point_type;
  78     typedef flags state_type;
  79
  80     static inline bool apply(Point const& point,
  81             PointOfSegment const& seg1, PointOfSegment const& seg2,
  82             flags& state)
  83     {
  84         calculation_type const tx = get<0>(point);
  85         calculation_type const ty = get<1>(point);
  86         calculation_type const x0 = get<0>(seg1);
  87         calculation_type const y0 = get<1>(seg1);
  88         calculation_type const x1 = get<0>(seg2);
  89         calculation_type const y1 = get<1>(seg2);
  90
  91         if (state.first)
  92         {
  93             state.first = false;
  94             state.yflag0 = y0 >= ty;
  95         }
  96
  97
  98         bool yflag1 = y1 >= ty;
  99         if (state.yflag0 != yflag1)
 100         {
 101             if ( ((y1-ty) * (x0-x1) >= (x1-tx) * (y0-y1)) == yflag1 )
 102             {
 103                 state.inside_flag = ! state.inside_flag;
 104             }
 105         }
 106         state.yflag0 = yflag1;
 107         return true;
 108     }
 109
 110     static inline int result(flags const& state)
 111     {
 112         return state.inside_flag ? 1 : -1;
 113     }
 114 };
 115
 116
 117
 118 }} // namespace strategy::within
 119
 120
 121 }} // namespace boost::geometry
 122
 123
 124 #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_POINT_IN_POLY_CROSSINGS_MULTIPLY_HPP