Boost C++ Libraries

Metafunction defining value as the closure (clockwise, counterclockwise) of the specified geometry type.

Synopsis

template<typename Geometry>
struct closure
      : public std::integral_constant< closure_selector, core_dispatch::closure< tag_t< Geometry >, util::remove_cptrref_t< Geometry > >::value >
{
  // ...
};

Template parameter(s)

Header

Either

#include <boost/geometry.hpp>

Or

#include <boost/geometry/core/closure.hpp>

	Note
	The closure is defined for any geometry type, but only has a real meaning for areal geometry types (ring, polygon, multi_polygon)

Complexity

Compile time

Example

Examine if a polygon is defined as "should be closed"

#include <iostream>

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/point_xy.hpp>

int main()
{
    using point_type = boost::geometry::model::d2::point_xy<double>;
    using polygon_type = boost::geometry::model::polygon<point_type>;

    boost::geometry::closure_selector clos = boost::geometry::closure<polygon_type>::value;

    std::cout << "closure: " << clos << std::endl
        << "(open = " << boost::geometry::open
        << ", closed = " << boost::geometry::closed
        << ") "<< std::endl;

    return 0;
}

Output:

closure: 1
(open = 0, closed = 1)

See also