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 //[centroid
11 //` Shows calculation of a centroid of a 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 "create_svg_two.hpp" /*->*/
20
main()21 int main()
22 {
23 typedef boost::geometry::model::d2::point_xy<double> point_type;
24 typedef boost::geometry::model::polygon<point_type> polygon_type;
25
26 polygon_type poly;
27 boost::geometry::read_wkt(
28 "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)"
29 "(4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", poly);
30
31 point_type p;
32 boost::geometry::centroid(poly, p);
33
34 std::cout << "centroid: " << boost::geometry::dsv(p) << std::endl;
35 /*<-*/ create_svg("centroid.svg", poly, p); /*->*/
36 return 0;
37 }
38
39 //]
40
41 //[centroid_output
42 /*`
43 Output:
44 [pre
45 centroid: (4.04663, 1.6349)
46 [$img/algorithms/centroid.png]
47 ]
48 Note that the centroid might be located in a hole or outside a polygon, easily.
49 */
50 //]
51
