boost/geometry/algorithms/detail/overlay/append_no_dups_or_spikes.hpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2
   3 // Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.
   4
   5 // This file was modified by Oracle on 2014.
   6 // Modifications copyright (c) 2014 Oracle and/or its affiliates.
   7
   8 // Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
   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_ALGORITHMS_DETAIL_OVERLAY_APPEND_NO_DUPS_OR_SPIKES_HPP
  15 #define BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_APPEND_NO_DUPS_OR_SPIKES_HPP
  16
  17 #include <boost/range.hpp>
  18
  19 #include <boost/geometry/algorithms/append.hpp>
  20 #include <boost/geometry/algorithms/detail/point_is_spike_or_equal.hpp>
  21 #include <boost/geometry/algorithms/detail/equals/point_point.hpp>
  22
  23 #include <boost/geometry/util/range.hpp>
  24
  25
  26 namespace boost { namespace geometry
  27 {
  28
  29
  30 #ifndef DOXYGEN_NO_DETAIL
  31 namespace detail { namespace overlay
  32 {
  33
  34 // TODO: move this / rename this
  35 template <typename Point1, typename Point2, typename RobustPolicy>
  36 inline bool points_equal_or_close(Point1 const& point1,
  37         Point2 const& point2,
  38         RobustPolicy const& robust_policy)
  39 {
  40     if (detail::equals::equals_point_point(point1, point2))
  41     {
  42         return true;
  43     }
  44
  45     if (! RobustPolicy::enabled)
  46     {
  47         return false;
  48     }
  49
  50     // Try using specified robust policy
  51     typedef typename geometry::robust_point_type
  52     <
  53         Point1,
  54         RobustPolicy
  55     >::type robust_point_type;
  56
  57     robust_point_type point1_rob, point2_rob;
  58     geometry::recalculate(point1_rob, point1, robust_policy);
  59     geometry::recalculate(point2_rob, point2, robust_policy);
  60
  61     return detail::equals::equals_point_point(point1_rob, point2_rob);
  62 }
  63
  64
  65 template <typename Range, typename Point, typename RobustPolicy>
  66 inline void append_no_dups_or_spikes(Range& range, Point const& point,
  67         RobustPolicy const& robust_policy)
  68 {
  69 #ifdef BOOST_GEOMETRY_DEBUG_INTERSECTION
  70     std::cout << "  add: ("
  71         << geometry::get<0>(point) << ", " << geometry::get<1>(point) << ")"
  72         << std::endl;
  73 #endif
  74     // The code below thies condition checks all spikes/dups
  75     // for geometries >= 3 points.
  76     // So we have to check the first potential duplicate differently
  77     if (boost::size(range) == 1
  78         && points_equal_or_close(*(boost::begin(range)), point, robust_policy))
  79     {
  80         return;
  81     }
  82
  83     traits::push_back<Range>::apply(range, point);
  84
  85     // If a point is equal, or forming a spike, remove the pen-ultimate point
  86     // because this one caused the spike.
  87     // If so, the now-new-pen-ultimate point can again cause a spike
  88     // (possibly at a corner). So keep doing this.
  89     // Besides spikes it will also avoid adding duplicates.
  90     while(boost::size(range) >= 3
  91             && point_is_spike_or_equal(point,
  92                 *(boost::end(range) - 3),
  93                 *(boost::end(range) - 2),
  94                 robust_policy))
  95     {
  96         // Use the Concept/traits, so resize and append again
  97         traits::resize<Range>::apply(range, boost::size(range) - 2);
  98         traits::push_back<Range>::apply(range, point);
  99     }
 100 }
 101
 102 template <typename Range, typename RobustPolicy>
 103 inline void clean_closing_dups_and_spikes(Range& range,
 104                 RobustPolicy const& robust_policy)
 105 {
 106     std::size_t const minsize
 107         = core_detail::closure::minimum_ring_size
 108             <
 109                 geometry::closure<Range>::value
 110             >::value;
 111
 112     if (boost::size(range) <= minsize)
 113     {
 114         return;
 115     }
 116
 117     typedef typename boost::range_iterator<Range>::type iterator_type;
 118     static bool const closed = geometry::closure<Range>::value == geometry::closed;
 119
 120 // TODO: the following algorithm could be rewritten to first look for spikes
 121 // and then erase some number of points from the beginning of the Range
 122
 123     bool found = false;
 124     do
 125     {
 126         found = false;
 127         iterator_type first = boost::begin(range);
 128         iterator_type second = first + 1;
 129         iterator_type ultimate = boost::end(range) - 1;
 130         if (closed)
 131         {
 132             ultimate--;
 133         }
 134
 135         // Check if closing point is a spike (this is so if the second point is
 136         // considered as a spike w.r.t. the last segment)
 137         if (point_is_spike_or_equal(*second, *ultimate, *first, robust_policy))
 138         {
 139             range::erase(range, first);
 140             if (closed)
 141             {
 142                 // Remove closing last point
 143                 range::resize(range, boost::size(range) - 1);
 144                 // Add new closing point
 145                 range::push_back(range, range::front(range));
 146             }
 147             found = true;
 148         }
 149     } while(found && boost::size(range) > minsize);
 150 }
 151
 152
 153 }} // namespace detail::overlay
 154 #endif // DOXYGEN_NO_DETAIL
 155
 156
 157 }} // namespace boost::geometry
 158
 159
 160 #endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_OVERLAY_APPEND_NO_DUPS_OR_SPIKES_HPP