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

 1// Boost.Geometry (aka GGL, Generic Geometry Library)
 2// QuickBook Example
 3
 4// Copyright (c) 2011 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
11//` Shows how to subtract one polygon from another polygon
12
13#include <iostream>
14#include <list>
15
16#include <boost/geometry.hpp>
17#include <boost/geometry/geometries/point_xy.hpp>
18#include <boost/geometry/geometries/polygon.hpp>
19#include <boost/geometry/domains/gis/io/wkt/wkt.hpp>
20
21#include <boost/foreach.hpp>
22/*<-*/ #include "create_svg_overlay.hpp" /*->*/
23
24int main()
25{
26    typedef boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > polygon;
27
28    polygon green, blue;
29
30    boost::geometry::read_wkt(
31        "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)"
32            "(4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", green);
33
34    boost::geometry::read_wkt(
35        "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);
36
37    std::list<polygon> output;
38    boost::geometry::difference(green, blue, output);
39
40    int i = 0;
41    std::cout << "green - blue:" << std::endl;
42    BOOST_FOREACH(polygon const& p, output)
43    {
44        std::cout << i++ << ": " << boost::geometry::area(p) << std::endl;
45    }
46
47    /*<-*/ create_svg("difference_a.svg", green, blue, output); /*->*/
48    output.clear();
49    boost::geometry::difference(blue, green, output);
50
51    i = 0;
52    std::cout << "blue - green:" << std::endl;
53    BOOST_FOREACH(polygon const& p, output)
54    {
55        std::cout << i++ << ": " << boost::geometry::area(p) << std::endl;
56    }
57
58    /*<-*/ create_svg("difference_b.svg", green, blue, output); /*->*/
59    return 0;
60}
61
62//]
63
64
65//[difference_output
66/*`
67Output:
68[pre
69green - blue:
700: 0.02375
711: 0.542951
722: 0.0149697
733: 0.226855
744: 0.839424
75
76[$img/algorithms/difference_a.png]
77
78blue - green:
790: 0.525154
801: 0.015
812: 0.181136
823: 0.128798
834: 0.340083
845: 0.307778
85
86[$img/algorithms/difference_b.png]
87]
88*/
89//]
90