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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:(null)1="http://www.w3.org/TR/REC-html40"><head><!--
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Copyright 2009-2010 Intel Corporation
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license banner
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-->
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<title>Boost Polygon Library: Polygon Concept</title>
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<meta http-equiv="content-type" content="text/html;charset=ISO-8859-1">
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<table style="margin: 0pt; padding: 0pt; width: 100%;" border="0" cellpadding="0" cellspacing="0"><tbody><tr>
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<td style="background-color: rgb(238, 238, 238);" nowrap="1" valign="top">
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<div style="padding: 5px;" align="center">
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<img border="0" src="images/boost.png" width="277" height="86"><a title="www.boost.org home page" href="http://www.boost.org/" tabindex="2" style="border: medium none ;">
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</a>
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</div>
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<div style="margin: 5px;">
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<h3 class="navbar">Contents</h3>
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<ul>
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<li><a href="index.htm">Boost.Polygon Main Page</a></li>
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<li><a href="gtl_design_overview.htm">Design Overview</a></li>
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<li><a href="gtl_isotropy.htm">Isotropy</a></li>
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<li><a href="gtl_coordinate_concept.htm">Coordinate Concept</a></li>
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<li><a href="gtl_interval_concept.htm">Interval Concept</a></li>
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<li><a href="gtl_point_concept.htm">Point Concept</a></li>
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<li><a href="gtl_rectangle_concept.htm">Rectangle Concept</a></li>
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<li><a href="gtl_polygon_90_concept.htm">Polygon 90 Concept</a></li>
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<li><a href="gtl_polygon_90_with_holes_concept.htm">Polygon 90 With Holes Concept</a></li>
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<li><a href="gtl_polygon_45_concept.htm">Polygon 45 Concept</a></li>
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<li><a href="gtl_polygon_45_with_holes_concept.htm">Polygon 45 With Holes Concept</a></li>
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<li>Polygon Concept</li>
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<li><a href="gtl_polygon_with_holes_concept.htm">Polygon With Holes Concept</a></li>
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<li><a href="gtl_polygon_90_set_concept.htm">Polygon 90 Set Concept</a></li>
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<li><a href="gtl_polygon_45_set_concept.htm">Polygon 45 Set Concept</a></li>
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<li><a href="gtl_polygon_set_concept.htm">Polygon Set Concept</a></li>
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<li><a href="gtl_connectivity_extraction_90.htm">Connectivity Extraction 90</a></li>
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<li><a href="gtl_connectivity_extraction_45.htm">Connectivity Extraction 45</a></li>
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<li><a href="gtl_connectivity_extraction.htm">Connectivity Extraction</a></li>
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<li><a href="gtl_property_merge_90.htm">Property Merge 90</a></li>
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<li><a href="gtl_property_merge_45.htm">Property Merge 45</a></li>
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<li><a href="gtl_property_merge.htm">Property Merge</a></li>
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</ul>
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<h3 class="navbar">Other Resources</h3>
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<ul>
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<li><a href="GTL_boostcon2009.pdf">GTL Boostcon 2009 Paper</a></li>
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<li><a href="GTL_boostcon_draft03.pdf">GTL Boostcon 2009
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Presentation</a></li>
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<li><a href="analysis.htm">Performance Analysis</a></li>
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<li><a href="gtl_tutorial.htm">Layout Versus Schematic Tutorial</a></li>
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<li><a href="gtl_minkowski_tutorial.htm">Minkowski Sum Tutorial</a></li>
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</ul>
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</div>
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<h3 class="navbar">Polygon Sponsor</h3>
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<div style="padding: 5px;" align="center">
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<img border="0" src="images/intlogo.gif" width="127" height="51">
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</div>
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</td>
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<td style="padding-left: 10px; padding-right: 10px; padding-bottom: 10px;" valign="top" width="100%">
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<!-- End Header -->
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<br>
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<p>
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</p><h1>Polygon Concept</h1>
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<p>
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<p>The polygon concept tag is <font face="Courier New">
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polygon_concept</font></p>
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<p>
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To register a user defined type as a model of
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<font face="Times New Roman">polygon </font>concept, specialize the
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geometry concept meta-function for that type. In the example below CPolygon is registered as a model of
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polygon concept.<p>
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<font face="Courier New">template <><br>
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struct geometry_concept<CPolygon> { typedef polygon_concept type; };</font><p>
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<font face="Times New Roman">The semantic of a polygon is that it can provide
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iterators over the points that represent its vertices. It is acceptable to
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have the last edge explict with the first and last point equal to each other or
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implied by this segement that would connect the first and last point. A
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mutable polygon must also be able to set its geometry based on an interator
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range over such points. A std::vector<point_data<int> > or std::list<point_data<int>
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>
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could be made models of polygon_concept by simply providing access to their
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iterators through traits. Library functions that create polygon objects
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require that those objects provide a default constructor.</font><p>
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<font face="Times New Roman">Below is shown the default polygon traits.
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Specialization of these traits is required for types that don't conform to the
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default behavior. Note that these same traits are also used by several
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other polygon concepts through SFINE enable template parameter. The SFINE
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enable parameter also allows the library to provide default specialization that
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work for any object that models the 90 degree polygon concepts.</font><p>
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<font face="Courier New">template <typename T, typename enable = gtl_yes><br>
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struct polygon_traits {};<br>
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<br>
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template <typename T><br>
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struct polygon_traits<T, <br>
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typename gtl_or_4<<br>
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typename gtl_same_type<typename geometry_concept<T>::type,
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polygon_concept>::type,<br>
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typename gtl_same_type<typename geometry_concept<T>::type,
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polygon_concept>::type,<br>
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typename gtl_same_type<typename geometry_concept<T>::type,
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polygon_with_holes_concept>::type,<br>
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typename gtl_same_type<typename geometry_concept<T>::type,
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polygon_with_holes_concept>::type<br>
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>::type> {<br>
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typedef typename T::coordinate_type coordinate_type;<br>
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typedef typename T::iterator_type iterator_type;<br>
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typedef typename T::point_type point_type;<br>
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static inline iterator_type begin_points(const T& t) {<br>
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return t.begin();<br>
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}<br>
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static inline iterator_type end_points(const T& t) {<br>
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return t.end();<br>
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}<br>
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static inline unsigned int size(const T& t) {<br>
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return t.size();<br>
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}<br>
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static inline winding_direction winding(const T& t) {<br>
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return unknown_winding;<br>
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}<br>
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};</font></p>
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<p><font face="Courier New">template <typename T, typename enable = void><br>
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struct polygon_mutable_traits {<br>
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template <typename iT><br>
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static inline T& set_points(T& t, iT input_begin, iT
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input_end) {<br>
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t.set(input_begin,
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input_end);<br>
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return t;<br>
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}<br>
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};</font></p>
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<p>Example code <a href="gtl_custom_polygon.htm">custom_polygon.cpp</a>
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demonstrates mapping a
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user defined polygon class to the library polygon_concept</p>
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<p>An object that is a model of <font face="Courier New">
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polygon_concept</font> can be viewed as a model of any of its
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refinements if it is determined at runtime to conform to the restriction of
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those concepts. This concept casting is accomplished through the
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<font face="Courier New">view_as<>()</font> function.</p>
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<p><font face="Courier New">view_as<rectangle_concept>(polygon_object)</font><br>
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<font face="Courier New">view_as<polygon_90_concept>(polygon_object)</font><br>
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<font face="Courier New">view_as<polygon_45_concept>(polygon_object)</font></p>
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<p>The return value of <font face="Courier New">view_as<>()</font> can be
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passed into any interface that expects an object of the conceptual type
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specified in its template parameter. </p>
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<h2>Functions</h2>
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<table border="1" width="100%" id="table1">
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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point_iterator_type <b>begin_points</b>(const T& polygon)</font></td>
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<td><font face="Times New Roman">Expects a model of polygon.
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Returns the begin iterator over the range of points that correspond to
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vertices of the polygon.</font></td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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point_iterator_type <b>end_points</b>(const T& polygon)</font></td>
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<td><font face="Times New Roman">Expects a model of polygon.
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Returns the end iterator over the range of points that correspond to
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vertices of the polygon.</font></td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T, typename
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iterator><br>
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void <b>set_points</b>(T& polygon, iterator b, iterator e)</font></td>
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<td><font face="Times New Roman">Expects a model of polygon.
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Sets the polygon to the point data range [b,e) that corresponds to
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vertices of a manhattan polygon.</font></td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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unsigned int <b>size</b>(const T& polygon)</font></td>
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<td><font face="Times New Roman">Returns the number of edges in the
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polygon.</font></td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T1, typename
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T2><br>
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T1& <b>assign</b>(T1& left, const T2& right)</font></td>
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<td>Copies data from right object that models polygon into left object
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that models polygon.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T,
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typename point_type><br>
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bool <b>contains</b>(const T&, const point_type& point, <br>
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bool consider_touch=true)</font></td>
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<td>Given an object that models polygon and an object that models
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point, returns true
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if the polygon contains the point. If the consider_touch
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flag is true will return true if the point lies along the boundary of
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the polygon. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">// get the center coordinate<br>
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template <typename T, typename point_type><br>
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void <b>center</b>(point_type& p, const T& polygon)</font></td>
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<td>Sets object that models point to the center point of the bounding
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box of an object that models polygon. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T,
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typename rectangle_type><br>
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bool <b>extents</b>(rectangle_type& bbox, const T& polygon)</font></td>
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<td>Sets object that models rectangle to the bounding box of an object
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that models polygon and returns true. Returns false and leaves
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bbox unchanged if polygon is empty. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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area_type <b>area</b>(const T& polygon)</font></td>
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<td>Returns the area of an object
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that models polygon. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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direction_1d <b>winding</b>(const T& polygon)</font></td>
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<td>Returns the winding direction of an object
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that models polygon, LOW == CLOCKWISE, HIGH = COUNTERCLOCKWISE.
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Complexity depends upon winding trait.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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coordinate_distance <b>perimeter</b>(const T& polygon)</font></td>
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<td>Returns the perimeter length of an object
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that models polygon. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T,
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typename transform_type><br>
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T& <b>transform</b>(T& polygon, const transform_type&)</font></td>
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<td>Applies transform() on the vertices of polygon and sets the polygon to that described by the result of
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transforming its vertices. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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T& <b>scale_up</b>(T& polygon, unsigned_area_type factor)</font></td>
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<td>Scales up coordinate of an object that models
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polygon by unsigned factor. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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T& <b>scale_down</b>(T& polygon, unsigned_area_type factor)</font></td>
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<td>Scales down coordinates of an object that models
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polygon by unsigned factor. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T, scaling_type><br>
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T& <b>scale</b>(T& rectangle, double scaling) </font></td>
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<td>Scales coordinates of an object that models polygon by floating
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point factor. Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T><br>
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T& <b>move</b>(T& polygon, orientation_2d,<br>
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coordinate_difference displacement)</font></td>
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<td>Adds displacement value to coordinate indicated by orientation_2d of
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vertices of an object that models polygon . Linear wrt. vertices.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename polygon_type, typename point_type><br>
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polygon_type& <b>convolve</b>(polygon_type& polygon,<br>
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const point_type& point)</font></td>
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<td>Convolves coordinate values of point with vertices of an
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object that models polygon. Linear wrt. vertices.</td>
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</tr>
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</table>
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<h1>Polygon Data</h1>
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<p>
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<p>The library provides a model of polygon concept declared
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<font face="Courier New">
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template<typename T> polygon_data </font>where T is the coordinate type.</p>
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<p>This data type is used internally when a polygon is needed and is available
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to the library user who finds it convenient to use a library polygon data type
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instead of providing their own. The data type is implemented to be
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convenient to use with the library traits.</p>
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<p>Example code <a href="gtl_polygon_usage.htm">polygon_usage.cpp</a>
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demonstrates using
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the library provided polygon data types and functions</p>
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<h2>Members</h2>
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<table border="1" width="100%" id="table2">
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<tr>
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<td width="586"><b><font face="Courier New">geometry_type</font></b></td>
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<td><font face="Times New Roman">polygon_concept</font></td>
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</tr>
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<tr>
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<td width="586"><b><font face="Courier New">coordinate_type</font></b></td>
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<td><font face="Times New Roman">T</font></td>
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</tr>
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<tr>
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<td width="586"><b><font face="Courier New">iterator_type</font></b></td>
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<td>Iterator over vertices point_data<T> vertices of polygon</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New"><b>polygon_data</b>()</font></td>
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<td><font face="Times New Roman">Default constructs the </font>polygon.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New"><b>polygon_data</b>(const
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polygon_data& that)</font></td>
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<td><font face="Times New Roman">Copy construct</font></td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">polygon_data& <b>operator=</b>(const
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polygon_data& that)</font></td>
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<td>Assignment operator.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename T2><b>
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<br> </b>polygon_data& <b>operator=</b>(const T2& that) const</font></td>
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<td>Assign from an object that is a model of polygon.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">iterator_type <b>begin</b>()
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const</font></td>
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<td>Get the begin iterator over vertices of the polygon.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">iterator_type <b>end</b>()
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const</font></td>
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<td>Get the end iterator over vertices of the polygon.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">std::size_t <b>size</b>() const</font></td>
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<td>Get the number of elements in the sequence stored to the polygon,
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usually equal to the number of edges of the polygon.</td>
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</tr>
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<tr>
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<td width="586"><font face="Courier New">template <typename iT><b>
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<br> </b>void <b>set</b>(iT begin_points, iT end_points)</font></td>
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<td>Sets the polygon to the iterator range of points. </td>
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</tr>
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</table>
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<tr>
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<td style="background-color: rgb(238, 238, 238);" nowrap="1" valign="top">
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</td>
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<td style="padding-left: 10px; padding-right: 10px; padding-bottom: 10px;" valign="top" width="100%">
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<table class="docinfo" rules="none" frame="void" id="table3">
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<colgroup>
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<col class="docinfo-name"><col class="docinfo-content">
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</colgroup>
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<tbody vAlign="top">
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<tr>
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<th class="docinfo-name">Copyright:</th>
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<td>Copyright <20> Intel Corporation 2008-2010.</td>
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</tr>
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<tr class="field">
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<th class="docinfo-name">License:</th>
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<td class="field-body">Distributed under the Boost Software License,
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Version 1.0. (See accompanying file <tt class="literal">
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<span class="pre">LICENSE_1_0.txt</span></tt> or copy at
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<a class="reference" target="_top" href="http://www.boost.org/LICENSE_1_0.txt">
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http://www.boost.org/LICENSE_1_0.txt</a>)</td>
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</tr>
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</table>
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</html> |