model::ring

A ring (aka linear ring) is a closed line which should not be selfintersecting.

Model of

Synopsis

template<typename Point, bool ClockWise, bool Closed, template< typename, typename > class Container,
         template< typename > class Allocator>
class model::ring
      : public std::vector< Point, std::allocator< Point > >
{
  // ...
};

Template parameter(s)

Parameter	Default	Description
typename Point		point type
bool ClockWise	true	true for clockwise direction, false for CounterClockWise direction
bool Closed	true	true for closed polygons (last point == first point), false open points
template< typename, typename > class Container	std::vector	container type, for example std::vector, std::deque
template< typename > class Allocator	std::allocator	container-allocator-type

Constructor(s)

Function	Description	Parameters
ring()	Default constructor, creating an empty ring.
template<typename Iterator> ring(Iterator begin, Iterator end)	Constructor with begin and end, filling the ring.	Iterator: begin: Iterator: end:
ring(std::initializer_list< Point > l)	Constructor taking std::initializer_list, filling the ring.	std::initializer_list< Point >: l:

Function

Description

Parameters

ring()

Default constructor, creating an empty ring.

template<typename Iterator>
ring(Iterator begin, Iterator end)

Constructor with begin and end, filling the ring.

Iterator: begin:

Iterator: end:

ring(std::initializer_list< Point > l)

Constructor taking std::initializer_list, filling the ring.

std::initializer_list< Point >: l:

Header

Either

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

#include <boost/geometry/geometries/ring.hpp>

Examples

Declaration and use of the Boost.Geometry model::ring, modelling the Ring Concept

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

namespace bg = boost::geometry;

int main()
{
    typedef bg::model::point<double, 2, bg::cs::cartesian> point_t;
    typedef bg::model::ring<point_t> ring_t; 

    ring_t ring1; 
    ring_t ring2{{0.0, 0.0}, {0.0, 5.0}, {5.0, 5.0}, {5.0, 0.0}, {0.0, 0.0}}; 

    bg::append(ring1, point_t(0.0, 0.0)); 
    bg::append(ring1, point_t(0.0, 5.0));
    bg::append(ring1, point_t(5.0, 5.0));
    bg::append(ring1, point_t(5.0, 0.0));
    bg::append(ring1, point_t(0.0, 0.0));

    double a = bg::area(ring1);

    std::cout << a << std::endl;

    return 0;
}

	Default parameters, clockwise, closed ring.
	Default-construct a ring.
	Construct a ring containing four points plus one closing point, using C++11 unified initialization syntax.
	Append point.

Output: