ceph/src/boost/boost/geometry/strategies/cartesian/buffer_end_flat.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2012-2014 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_STRATEGIES_CARTESIAN_BUFFER_END_FLAT_HPP
  10 #define BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_FLAT_HPP
  11
  12 #include <boost/geometry/core/cs.hpp>
  13 #include <boost/geometry/strategies/tags.hpp>
  14 #include <boost/geometry/strategies/side.hpp>
  15 #include <boost/geometry/util/math.hpp>
  16 #include <boost/geometry/util/select_most_precise.hpp>
  17
  18 #include <boost/geometry/strategies/buffer.hpp>
  19
  20
  21
  22 namespace boost { namespace geometry
  23 {
  24
  25
  26 namespace strategy { namespace buffer
  27 {
  28
  29
  30 /*!
  31 \brief Let the buffer create flat ends
  32 \ingroup strategies
  33 \details This strategy can be used as EndStrategy for the buffer algorithm.
  34     It creates a flat end for each linestring-end. It can be applied
  35     for (multi)linestrings. Also it is applicable for spikes in (multi)polygons.
  36     This strategy is only applicable for Cartesian coordinate systems.
  37
  38 \qbk{
  39 [heading Example]
  40 [buffer_end_flat]
  41 [heading Output]
  42 [$img/strategies/buffer_end_flat.png]
  43 [heading See also]
  44 \* [link geometry.reference.algorithms.buffer.buffer_7_with_strategies buffer (with strategies)]
  45 \* [link geometry.reference.strategies.strategy_buffer_end_round end_round]
  46 }
  47  */
  48 class end_flat
  49 {
  50
  51 public :
  52
  53 #ifndef DOXYGEN_SHOULD_SKIP_THIS
  54     //! Fills output_range with a flat end
  55     template <typename Point, typename RangeOut, typename DistanceStrategy>
  56     inline void apply(Point const& penultimate_point,
  57                 Point const& perp_left_point,
  58                 Point const& ultimate_point,
  59                 Point const& perp_right_point,
  60                 buffer_side_selector side,
  61                 DistanceStrategy const& distance,
  62                 RangeOut& range_out) const
  63     {
  64         typedef typename coordinate_type<Point>::type coordinate_type;
  65
  66         typedef typename geometry::select_most_precise
  67         <
  68             coordinate_type,
  69             double
  70         >::type promoted_type;
  71
  72         promoted_type const dist_left = distance.apply(penultimate_point, ultimate_point, buffer_side_left);
  73         promoted_type const dist_right = distance.apply(penultimate_point, ultimate_point, buffer_side_right);
  74
  75         bool reversed = (side == buffer_side_left && dist_right < 0 && -dist_right > dist_left)
  76                     || (side == buffer_side_right && dist_left < 0 && -dist_left > dist_right)
  77                     ;
  78         if (reversed)
  79         {
  80             range_out.push_back(perp_right_point);
  81             range_out.push_back(perp_left_point);
  82         }
  83         else
  84         {
  85             range_out.push_back(perp_left_point);
  86             range_out.push_back(perp_right_point);
  87         }
  88         // Don't add the ultimate_point (endpoint of the linestring).
  89         // The buffer might be generated completely at one side.
  90         // In other cases it does no harm but is further useless
  91     }
  92
  93     template <typename NumericType>
  94     static inline NumericType max_distance(NumericType const& distance)
  95     {
  96         return distance;
  97     }
  98
  99     //! Returns the piece_type (flat end)
 100     static inline piece_type get_piece_type()
 101     {
 102         return buffered_flat_end;
 103     }
 104 #endif // DOXYGEN_SHOULD_SKIP_THIS
 105 };
 106
 107
 108 }} // namespace strategy::buffer
 109
 110 }} // namespace boost::geometry
 111
 112 #endif // BOOST_GEOMETRY_STRATEGIES_CARTESIAN_BUFFER_END_FLAT_HPP