ceph/src/boost/libs/geometry/doc/src/examples/algorithms/difference_inserter.cpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2 // QuickBook Example
   3
   4 // Copyright (c) 2011-2012 Barend Gehrels, Amsterdam, the Netherlands.
   5
   6 // Use, modification and distribution is subject to the Boost Software License,
   7 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   8 // http://www.boost.org/LICENSE_1_0.txt)
   9
  10 //[difference_inserter
  11 //` Shows how the difference_inserter function can be used
  12
  13 #include <iostream>
  14 #include <vector>
  15
  16 #include <boost/geometry.hpp>
  17 #include <boost/geometry/geometries/point_xy.hpp>
  18 #include <boost/geometry/geometries/polygon.hpp>
  19
  20 #include <boost/foreach.hpp>
  21 /*<-*/ #include "create_svg_overlay.hpp" /*->*/
  22
  23 int main()
  24 {
  25     typedef boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > polygon;
  26
  27     polygon green, blue;
  28
  29     boost::geometry::read_wkt(
  30         "POLYGON((2 1.3,2.4 1.7,2.8 1.8,3.4 1.2,3.7 1.6,3.4 2,4.1 3,5.3 2.6,5.4 1.2,4.9 0.8,2.9 0.7,2 1.3)"
  31             "(4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", green);
  32
  33     boost::geometry::read_wkt(
  34         "POLYGON((4.0 -0.5 , 3.5 1.0 , 2.0 1.5 , 3.5 2.0 , 4.0 3.5 , 4.5 2.0 , 6.0 1.5 , 4.5 1.0 , 4.0 -0.5))", blue);
  35
  36     std::vector<polygon> output;
  37
  38     // Note that this sample simulates the symmetric difference,
  39     // which is also available as a separate algorithm.
  40     // It chains the output iterator returned by the function to the second instance.
  41     boost::geometry::difference_inserter<polygon>
  42         (
  43             green, blue,
  44                 boost::geometry::difference_inserter<polygon>
  45                     (
  46                         blue, green,
  47                         std::back_inserter(output)
  48                     )
  49         );
  50
  51
  52     int i = 0;
  53     std::cout << "(blue \ green) u (green \ blue):" << std::endl;
  54     BOOST_FOREACH(polygon const& p, output)
  55     {
  56         std::cout << i++ << ": " << boost::geometry::area(p) << std::endl;
  57     }
  58
  59     /*<-*/ create_svg("difference_inserter.svg", green, blue, output); /*->*/
  60     return 0;
  61 }
  62
  63 //]
  64
  65
  66 //[difference_inserter_output
  67 /*`
  68 Output:
  69 [pre
  70 (blue \\ green) u (green \\ blue):
  71 0: 0.525154
  72 1: 0.015
  73 2: 0.181136
  74 3: 0.128798
  75 4: 0.340083
  76 5: 0.307778
  77 6: 0.02375
  78 7: 0.542951
  79 8: 0.0149697
  80 9: 0.226855
  81 10: 0.839424
  82
  83 [$img/algorithms/sym_difference.png]
  84
  85 ]
  86 */
  87 //]