| // Boost.Geometry (aka GGL, Generic Geometry Library) |
| // QuickBook Example |
| |
| // Copyright (c) 2011 Barend Gehrels, Amsterdam, the Netherlands. |
| |
| // Use, modification and distribution is subject to the Boost Software License, |
| // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
| // http://www.boost.org/LICENSE_1_0.txt) |
| |
| //[centroid |
| //` Shows calculation of a centroid of a polygon |
| |
| #include <iostream> |
| #include <list> |
| |
| #include <boost/geometry.hpp> |
| #include <boost/geometry/geometries/point_xy.hpp> |
| #include <boost/geometry/geometries/polygon.hpp> |
| |
| #include <boost/geometry/domains/gis/io/wkt/wkt.hpp> |
| /*<-*/ #include "create_svg_two.hpp" /*->*/ |
| |
| int main() |
| { |
| typedef boost::geometry::model::d2::point_xy<double> point_type; |
| typedef boost::geometry::model::polygon<point_type> polygon_type; |
| |
| polygon_type poly; |
| boost::geometry::read_wkt( |
| "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)" |
| "(4.0 2.0, 4.2 1.4, 4.8 1.9, 4.4 2.2, 4.0 2.0))", poly); |
| |
| point_type p; |
| boost::geometry::centroid(poly, p); |
| |
| std::cout << "centroid: " << boost::geometry::dsv(p) << std::endl; |
| /*<-*/ create_svg("centroid.svg", poly, p); /*->*/ |
| return 0; |
| } |
| |
| //] |
| |
| //[centroid_output |
| /*` |
| Output: |
| [pre |
| centroid: (4.04663, 1.6349) |
| [$img/algorithms/centroid.png] |
| ] |
| Note that the centroid might be located in a hole or outside a polygon, easily. |
| */ |
| //] |