| [/============================================================================ |
| Boost.Geometry (aka GGL, Generic Geometry Library) |
| |
| Copyright (c) 2009-2011 Mateusz Loskot, London, UK. |
| Copyright (c) 2009-2011 Barend Gehrels, Amsterdam, the Netherlands. |
| Copyright (c) 2009-2011 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_polygon Polygon Concept] |
| |
| [heading Description] |
| [concept Polygon..polygon] |
| |
| A polygon is ['A polygon is a planar surface defined by one exterior boundary and zero or more interior boundaries.] |
| ([@http://portal.opengeospatial.org/files/?artifact_id=25355 opengeospatial]). |
| |
| So the definition of a Boost.Geometry polygon differs a bit from e.g. Wiki, where a polygon does not have holes. A |
| polygon of Boost.Geometry is a polygon with or without holes. |
| ['(A polygon without holes is a ['helper geometry] within Boost.Geometry, and referred to as a ring.)] |
| |
| [heading Concept Definition] |
| |
| The Polygon Concept is defined as following: |
| |
| * there must be a specialization of `traits::tag` defining `polygon_tag` as type |
| * there must be a specialization of `traits::ring_type` defining the type of its exterior ring and interior rings as type |
| * this type defined by `ring_type` must fulfill the [link geometry.reference.concepts.concept_ring Ring Concept] |
| * there must be a specialization of `traits::interior_type` defining the type of the collection of its interior rings as type; |
| this collection itself must fulfill a Boost.Range Random Access Range Concept |
| * there must be a specialization of `traits::exterior_ring` with two functions named `get`, returning the exterior ring, one being const, the other being non const |
| * there must be a specialization of `traits::interior_rings` with two functions named `get`, returning the interior rings, one being const, the other being non const |
| |
| [heading Available Models] |
| * [link geometry.reference.models.model_polygon polygon] |
| * a Boost.Polygon polygon_with_holes_data (requires `#include boost/geometry/geometries/adapted/boost_polygon/polygon.hpp>`) |
| |
| [endsect] |
