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<div class="titlepage"><div><div><h4 class="title">
<a name="geometry.reference.algorithms.convex_hull"></a><a class="link" href="convex_hull.html" title="convex_hull">convex_hull</a>
</h4></div></div></div>
<p>
<a class="indexterm" name="id846714"></a>
Calculates the convex hull of a geometry.
</p>
<a name="geometry.reference.algorithms.convex_hull.description"></a><h6>
<a name="geometry.reference.algorithms.convex_hull.description-heading"></a>
<a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.description">Description</a>
</h6>
<p>
The free function convex_hull calculates the convex hull of a geometry.
</p>
<a name="geometry.reference.algorithms.convex_hull.synopsis"></a><h6>
<a name="geometry.reference.algorithms.convex_hull.synopsis-heading"></a>
<a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.synopsis">Synopsis</a>
</h6>
<p>
</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Geometry1</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Geometry2</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">convex_hull</span><span class="special">(</span><span class="identifier">Geometry1</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">geometry</span><span class="special">,</span> <span class="identifier">Geometry2</span> <span class="special">&amp;</span> <span class="identifier">hull</span><span class="special">)</span></pre>
<p>
</p>
<a name="geometry.reference.algorithms.convex_hull.parameters"></a><h6>
<a name="geometry.reference.algorithms.convex_hull.parameters-heading"></a>
<a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.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>
Geometry1 const &amp;
</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, input geometry
</p>
</td>
</tr>
<tr>
<td>
<p>
Geometry2 &amp;
</p>
</td>
<td>
<p>
Any type fulfilling a Geometry Concept
</p>
</td>
<td>
<p>
hull
</p>
</td>
<td>
<p>
A model of the specified concept which is set to the convex hull
</p>
</td>
</tr>
</tbody>
</table></div>
<a name="geometry.reference.algorithms.convex_hull.header"></a><h6>
<a name="geometry.reference.algorithms.convex_hull.header-heading"></a>
<a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.header">Header</a>
</h6>
<p>
Either
</p>
<p>
<code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span></code>
</p>
<p>
Or
</p>
<p>
<code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</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">convex_hull</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
</p>
<a name="geometry.reference.algorithms.convex_hull.complexity"></a><h6>
<a name="geometry.reference.algorithms.convex_hull.complexity-heading"></a>
<a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.complexity">Complexity</a>
</h6>
<p>
Linear
</p>
<a name="geometry.reference.algorithms.convex_hull.example"></a><h6>
<a name="geometry.reference.algorithms.convex_hull.example-heading"></a>
<a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.example">Example</a>
</h6>
<p>
Shows how to generate the convex_hull of a geometry
</p>
<p>
</p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</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="keyword">int</span> <span class="identifier">main</span><span class="special">()</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">&lt;</span><span class="keyword">double</span><span class="special">,</span> <span class="keyword">double</span><span class="special">&gt;</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">&lt;</span><span class="identifier">point</span><span class="special">&gt;</span> <span class="identifier">polygon</span><span class="special">;</span>
<span class="identifier">polygon</span> <span class="identifier">poly</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">read_wkt</span><span class="special">(</span><span class="string">"polygon((2.0 1.3, 2.4 1.7, 2.8 1.8, 3.4 1.2, 3.7 1.6,3.4 2.0, 4.1 3.0"</span>
<span class="string">", 5.3 2.6, 5.4 1.2, 4.9 0.8, 2.9 0.7,2.0 1.3))"</span><span class="special">,</span> <span class="identifier">poly</span><span class="special">);</span>
<span class="identifier">polygon</span> <span class="identifier">hull</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">convex_hull</span><span class="special">(</span><span class="identifier">poly</span><span class="special">,</span> <span class="identifier">hull</span><span class="special">);</span>
<span class="keyword">using</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">std</span><span class="special">::</span><span class="identifier">cout</span>
<span class="special">&lt;&lt;</span> <span class="string">"polygon: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">dsv</span><span class="special">(</span><span class="identifier">poly</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span>
<span class="special">&lt;&lt;</span> <span class="string">"hull: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">dsv</span><span class="special">(</span><span class="identifier">hull</span><span class="special">)</span> <span class="special">&lt;&lt;</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">polygon: (((2, 1.3), (2.4, 1.7), (2.8, 1.8), (3.4, 1.2), (3.7, 1.6), (3.4, 2), (4.1, 3), (5.3, 2.6), (5.4, 1.2), (4.9, 0.8), (2.9, 0.7), (2, 1.3)))
hull: (((2, 1.3), (2.4, 1.7), (4.1, 3), (5.3, 2.6), (5.4, 1.2), (4.9, 0.8), (2.9, 0.7), (2, 1.3)))
<img src="../../../img/algorithms/convex_hull.png" alt="convex_hull">
</pre>
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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>)
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