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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closure

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

Synopsis

template<typename Geometry>
struct closure
{
  // ...
};

Template parameter(s)

Parameter

Description

typename Geometry

Any type fulfilling a Geometry Concept

Header

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

[Note] 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()
{
    typedef boost::geometry::model::d2::point_xy<double> point_type;
    typedef boost::geometry::model::polygon<point_type> polygon_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

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