| Home | Libraries | People | FAQ | More

#### point_order

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

###### Synopsis

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

###### Template parameter(s)

Parameter | Description
--- | ---
typename Geometry | Any type fulfilling a Geometry Concept

###### Header

`#include <boost/geometry/core/point_order.hpp>`

| Note
The point order 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 the expected point order of a polygon type

    #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, false> polygon_type;

        boost::geometry::order_selector order = boost::geometry::point_order<polygon_type>::value;

        std::cout << "order: " << order << std::endl
            << "(clockwise = " << boost::geometry::clockwise
            << ", counterclockwise = " << boost::geometry::counterclockwise
            << ") "<< std::endl;

        return 0;
    }

Output:

    order: 2
    (clockwise = 1, counterclockwise = 2)

###### See also

- The order_selector enumeration