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[/============================================================================
Boost.Geometry (aka GGL, Generic Geometry Library)
Copyright (c) 2009-2012 Mateusz Loskot, London, UK.
Copyright (c) 2009-2012 Barend Gehrels, Amsterdam, the Netherlands.
Copyright (c) 2009-2012 Bruno Lalande, Paris, France.
Use, modification and distribution is subject to the Boost Software License,
Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
=============================================================================/]
[section:concept_ring Ring Concept]
[heading Description]
[concept Ring..ring]
[note Also called linear ring, but we explicitly refer to a filled feature here]
[heading Concept Definition]
The Ring Concept is defined as following:
* there must be a specialization of `traits::tag` defining `ring_tag` as type
* it must behave like a Boost.Range Random Access Range
* The type defined by the metafunction `range_value<...>::type` must fulfill
the [link geometry.reference.concepts.concept_point Point Concept]
* there might be a specialization of `traits::point_order` defining the order or orientation of its points, `clockwise` or `counterclockwise`
* there might be a specialization of `traits::closure` defining the closure, `open` or `closed`
[heading Rules]
Besides the Concepts, which are checks on compile-time, there are
rules that valid rings must fulfill. See the
[link geometry.reference.concepts.concept_polygon Polygon Concept] for more information
on the rules a polygon (and also a ring) must fulfill.
[heading Available Models]
* [link geometry.reference.models.model_ring ring]
* a Boost.Polygon polygon_data (requires `#include boost/geometry/geometries/adapted/boost_polygon/ring.hpp>`)
[see_boost_range_sample Ring]
[endsect]