Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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Boost.Polygon's polygon_with_holes_data

Boost.Polygon's polygon type supporting holes (boost::polygon::polygon_with_holes_data) is adapted to the Boost.Geometry Polygon Concept.

Description

Boost.Polygon's points (as well as polygons) can be used by Boost.Geometry. The two libraries can therefore be used together. Using a boost::polygon::polygon_with_holes_data<...>, algorithms from both Boost.Polygon and Boost.Geometry can be called.

Model of

Polygon Concept

Header

#include <boost/geometry/geometries/adapted/boost_polygon.hpp>

The standard header boost/geometry.hpp does not include this header.

Example

Shows how to use Boost.Polygon polygon_with_holes_data within Boost.Geometry

#include <iostream>
#include <boost/geometry.hpp>
#include <boost/geometry/geometries/adapted/boost_polygon.hpp>

int main()
{
    typedef boost::polygon::polygon_with_holes_data<int> polygon;
    typedef boost::polygon::polygon_traits<polygon>::point_type point;
    typedef boost::polygon::polygon_with_holes_traits<polygon>::hole_type hole;

    point pts[5] = {
        boost::polygon::construct<point>(0, 0),
        boost::polygon::construct<point>(0, 10),
        boost::polygon::construct<point>(10, 10),
        boost::polygon::construct<point>(10, 0),
        boost::polygon::construct<point>(0, 0)
    };
    point hole_pts[5] = {
        boost::polygon::construct<point>(1, 1),
        boost::polygon::construct<point>(9, 1),
        boost::polygon::construct<point>(9, 9),
        boost::polygon::construct<point>(1, 9),
        boost::polygon::construct<point>(1, 1)
    };

    hole hls[1];
    boost::polygon::set_points(hls[0], hole_pts, hole_pts+5);

    polygon poly;
    boost::polygon::set_points(poly, pts, pts+5);
    boost::polygon::set_holes(poly, hls, hls+1);

    std::cout << "Area (using Boost.Geometry): "
        << boost::geometry::area(poly) << std::endl;
    std::cout << "Area (using Boost.Polygon): "
        << boost::polygon::area(poly) << std::endl;

    return 0;
}

Output:

Area (using Boost.Geometry): 36
Area (using Boost.Polygon): 36

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