/Src/Dependencies/Boost/libs/geometry/doc/src/examples/algorithms/difference.cpp

http://hadesmem.googlecode.com/ · C++ · 90 lines · 37 code · 19 blank · 34 comment · 0 complexity · 440ab51ffe98430be02df4076264440f MD5 · raw file

  1. // Boost.Geometry (aka GGL, Generic Geometry Library)
  2. // QuickBook Example
  3. // Copyright (c) 2011 Barend Gehrels, Amsterdam, the Netherlands.
  4. // Use, modification and distribution is subject to the Boost Software License,
  5. // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  6. // http://www.boost.org/LICENSE_1_0.txt)
  7. //[difference
  8. //` Shows how to subtract one polygon from another polygon
  9. #include <iostream>
  10. #include <list>
  11. #include <boost/geometry.hpp>
  12. #include <boost/geometry/geometries/point_xy.hpp>
  13. #include <boost/geometry/geometries/polygon.hpp>
  14. #include <boost/geometry/domains/gis/io/wkt/wkt.hpp>
  15. #include <boost/foreach.hpp>
  16. /*<-*/ #include "create_svg_overlay.hpp" /*->*/
  17. int main()
  18. {
  19. typedef boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > polygon;
  20. polygon green, blue;
  21. boost::geometry::read_wkt(
  22. "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)"
  23. "(4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", green);
  24. boost::geometry::read_wkt(
  25. "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);
  26. std::list<polygon> output;
  27. boost::geometry::difference(green, blue, output);
  28. int i = 0;
  29. std::cout << "green - blue:" << std::endl;
  30. BOOST_FOREACH(polygon const& p, output)
  31. {
  32. std::cout << i++ << ": " << boost::geometry::area(p) << std::endl;
  33. }
  34. /*<-*/ create_svg("difference_a.svg", green, blue, output); /*->*/
  35. output.clear();
  36. boost::geometry::difference(blue, green, output);
  37. i = 0;
  38. std::cout << "blue - green:" << std::endl;
  39. BOOST_FOREACH(polygon const& p, output)
  40. {
  41. std::cout << i++ << ": " << boost::geometry::area(p) << std::endl;
  42. }
  43. /*<-*/ create_svg("difference_b.svg", green, blue, output); /*->*/
  44. return 0;
  45. }
  46. //]
  47. //[difference_output
  48. /*`
  49. Output:
  50. [pre
  51. green - blue:
  52. 0: 0.02375
  53. 1: 0.542951
  54. 2: 0.0149697
  55. 3: 0.226855
  56. 4: 0.839424
  57. [$img/algorithms/difference_a.png]
  58. blue - green:
  59. 0: 0.525154
  60. 1: 0.015
  61. 2: 0.181136
  62. 3: 0.128798
  63. 4: 0.340083
  64. 5: 0.307778
  65. [$img/algorithms/difference_b.png]
  66. ]
  67. */
  68. //]