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| <div class="section"> |
| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="geometry.reference.algorithms.clear"></a><a class="link" href="clear.html" title="clear">clear</a> |
| </h4></div></div></div> |
| <p> |
| <a class="indexterm" name="id843150"></a> |
| Clears a linestring, ring or polygon (exterior+interiors) or multi*. |
| </p> |
| <a name="geometry.reference.algorithms.clear.description"></a><h6> |
| <a name="geometry.reference.algorithms.clear.description-heading"></a> |
| <a class="link" href="clear.html#geometry.reference.algorithms.clear.description">Description</a> |
| </h6> |
| <p> |
| Generic function to clear a geometry. All points will be removed from the |
| collection or collections making up the geometry. In most cases this is |
| equivalent to the .clear() method of a std::vector<...>. In the case |
| of a polygon, this clear functionality is automatically called for the |
| exterior ring, and for the interior ring collection. In the case of a point, |
| boxes and segments, nothing will happen. |
| </p> |
| <a name="geometry.reference.algorithms.clear.synopsis"></a><h6> |
| <a name="geometry.reference.algorithms.clear.synopsis-heading"></a> |
| <a class="link" href="clear.html#geometry.reference.algorithms.clear.synopsis">Synopsis</a> |
| </h6> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">></span> |
| <span class="keyword">void</span> <span class="identifier">clear</span><span class="special">(</span><span class="identifier">Geometry</span> <span class="special">&</span> <span class="identifier">geometry</span><span class="special">)</span></pre> |
| <p> |
| </p> |
| <a name="geometry.reference.algorithms.clear.parameters"></a><h6> |
| <a name="geometry.reference.algorithms.clear.parameters-heading"></a> |
| <a class="link" href="clear.html#geometry.reference.algorithms.clear.parameters">Parameters</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Type |
| </p> |
| </th> |
| <th> |
| <p> |
| Concept |
| </p> |
| </th> |
| <th> |
| <p> |
| Name |
| </p> |
| </th> |
| <th> |
| <p> |
| Description |
| </p> |
| </th> |
| </tr></thead> |
| <tbody><tr> |
| <td> |
| <p> |
| Geometry & |
| </p> |
| </td> |
| <td> |
| <p> |
| Any type fulfilling a Geometry Concept |
| </p> |
| </td> |
| <td> |
| <p> |
| geometry |
| </p> |
| </td> |
| <td> |
| <p> |
| A model of the specified concept which will be cleared |
| </p> |
| </td> |
| </tr></tbody> |
| </table></div> |
| <a name="geometry.reference.algorithms.clear.header"></a><h6> |
| <a name="geometry.reference.algorithms.clear.header-heading"></a> |
| <a class="link" href="clear.html#geometry.reference.algorithms.clear.header">Header</a> |
| </h6> |
| <p> |
| Either |
| </p> |
| <p> |
| <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> |
| </p> |
| <p> |
| Or |
| </p> |
| <p> |
| <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">algorithms</span><span class="special">/</span><span class="identifier">clear</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> |
| </p> |
| <a name="geometry.reference.algorithms.clear.behavior"></a><h6> |
| <a name="geometry.reference.algorithms.clear.behavior-heading"></a> |
| <a class="link" href="clear.html#geometry.reference.algorithms.clear.behavior">Behavior</a> |
| </h6> |
| <div class="informaltable"><table class="table"> |
| <colgroup> |
| <col> |
| <col> |
| </colgroup> |
| <thead><tr> |
| <th> |
| <p> |
| Case |
| </p> |
| </th> |
| <th> |
| <p> |
| Behavior |
| </p> |
| </th> |
| </tr></thead> |
| <tbody> |
| <tr> |
| <td> |
| <p> |
| Point |
| </p> |
| </td> |
| <td> |
| <p> |
| Nothing happens, geometry is unchanged |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Segment |
| </p> |
| </td> |
| <td> |
| <p> |
| Nothing happens, geometry is unchanged |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Rectangle |
| </p> |
| </td> |
| <td> |
| <p> |
| Nothing happens, geometry is unchanged |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Linestring |
| </p> |
| </td> |
| <td> |
| <p> |
| Linestring is cleared |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Ring |
| </p> |
| </td> |
| <td> |
| <p> |
| Ring is cleared |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Polygon |
| </p> |
| </td> |
| <td> |
| <p> |
| The exterior ring is cleared and all interior rings are removed |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Multi Point |
| </p> |
| </td> |
| <td> |
| <p> |
| Multi Point is cleared |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Multi Linestring |
| </p> |
| </td> |
| <td> |
| <p> |
| Multi Linestring is cleared |
| </p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p> |
| Multi Polygon |
| </p> |
| </td> |
| <td> |
| <p> |
| Multi Polygon is cleared |
| </p> |
| </td> |
| </tr> |
| </tbody> |
| </table></div> |
| <a name="geometry.reference.algorithms.clear.complexity"></a><h6> |
| <a name="geometry.reference.algorithms.clear.complexity-heading"></a> |
| <a class="link" href="clear.html#geometry.reference.algorithms.clear.complexity">Complexity</a> |
| </h6> |
| <p> |
| Constant |
| </p> |
| <a name="geometry.reference.algorithms.clear.example"></a><h6> |
| <a name="geometry.reference.algorithms.clear.example-heading"></a> |
| <a class="link" href="clear.html#geometry.reference.algorithms.clear.example">Example</a> |
| </h6> |
| <p> |
| Shows how to clear a ring or polygon |
| </p> |
| <p> |
| |
| </p> |
| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> |
| |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">polygon</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">ring</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">adapted</span><span class="special">/</span><span class="identifier">boost_tuple</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| |
| <span class="identifier">BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS</span><span class="special">(</span><span class="identifier">cs</span><span class="special">::</span><span class="identifier">cartesian</span><span class="special">)</span> |
| |
| <span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">assign</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| |
| <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> |
| <span class="special">{</span> |
| <span class="keyword">using</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">assign</span><span class="special">::</span><span class="identifier">tuple_list_of</span><span class="special">;</span> |
| |
| <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">tuple</span><span class="special"><</span><span class="keyword">float</span><span class="special">,</span> <span class="keyword">float</span><span class="special">></span> <span class="identifier">point</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">polygon</span><span class="special"><</span><span class="identifier">point</span><span class="special">></span> <span class="identifier">polygon</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">ring</span><span class="special"><</span><span class="identifier">point</span><span class="special">></span> <span class="identifier">ring</span><span class="special">;</span> |
| |
| <span class="identifier">polygon</span> <span class="identifier">poly</span><span class="special">;</span> |
| |
| <span class="comment">// Fill the polygon (using its own methods + Boost.Assign)</span> |
| <span class="identifier">poly</span><span class="special">.</span><span class="identifier">outer</span><span class="special">()</span> <span class="special">=</span> <span class="identifier">tuple_list_of</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">9</span><span class="special">)(</span><span class="number">10</span><span class="special">,</span> <span class="number">10</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">);</span> |
| <span class="identifier">poly</span><span class="special">.</span><span class="identifier">inners</span><span class="special">().</span><span class="identifier">push_back</span><span class="special">(</span><span class="identifier">tuple_list_of</span><span class="special">(</span><span class="number">1</span><span class="special">,</span> <span class="number">2</span><span class="special">)(</span><span class="number">4</span><span class="special">,</span> <span class="number">6</span><span class="special">)(</span><span class="number">2</span><span class="special">,</span> <span class="number">8</span><span class="special">)(</span><span class="number">1</span><span class="special">,</span> <span class="number">2</span><span class="special">));</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">poly</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">clear</span><span class="special">(</span><span class="identifier">poly</span><span class="special">);</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">poly</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| |
| <span class="comment">// Create a ring using Boost.Assign</span> |
| <span class="identifier">ring</span> <span class="identifier">r</span> <span class="special">=</span> <span class="identifier">tuple_list_of</span><span class="special">(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">9</span><span class="special">)(</span><span class="number">8</span><span class="special">,</span> <span class="number">8</span><span class="special">)(</span><span class="number">0</span><span class="special">,</span> <span class="number">0</span><span class="special">);</span> |
| |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">r</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">clear</span><span class="special">(</span><span class="identifier">r</span><span class="special">);</span> |
| <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">r</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> |
| |
| <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> |
| <span class="special">}</span> |
| |
| </pre> |
| <p> |
| </p> |
| <p> |
| Output: |
| </p> |
| <pre class="programlisting">(((0, 0), (0, 10), (11, 11), (0, 0)), ((0, 0), (0, 10), (11, 11), (0, 0))) |
| (()) |
| ((0, 0), (0, 9), (8, 8), (0, 0)) |
| () |
| </pre> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2011 Barend Gehrels, Bruno Lalande, Mateusz Loskot<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
| </p> |
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