libs/geometry/doc/html/geometry/reference/algorithms/convex_hull.html

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  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="geometry.reference.algorithms.convex_hull"></a><a class="link" href="convex_hull.html" title="convex_hull">convex_hull</a>
  28 </h4></div></div></div>
  29 <p>
  30           <a class="indexterm" name="idm46187006077776"></a>
  31 Calculates the convex hull of a geometry.
  32         </p>
  33 <h6>
  34 <a name="geometry.reference.algorithms.convex_hull.h0"></a>
  35           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.description"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.description">Description</a>
  36         </h6>
  37 <p>
  38           The free function convex_hull calculates the convex hull of a geometry.
  39         </p>
  40 <h6>
  41 <a name="geometry.reference.algorithms.convex_hull.h1"></a>
  42           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.synopsis"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.synopsis">Synopsis</a>
  43         </h6>
  44 <p>
  45 </p>
  46 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">OutputGeometry</span><span class="special">&gt;</span>
  47 <span class="keyword">void</span> <span class="identifier">convex_hull</span><span class="special">(</span><span class="identifier">Geometry</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">geometry</span><span class="special">,</span> <span class="identifier">OutputGeometry</span> <span class="special">&amp;</span> <span class="identifier">hull</span><span class="special">)</span></pre>
  48 <p>
  49         </p>
  50 <h6>
  51 <a name="geometry.reference.algorithms.convex_hull.h2"></a>
  52           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.parameters"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.parameters">Parameters</a>
  53         </h6>
  54 <div class="informaltable"><table class="table">
  55 <colgroup>
  56 <col>
  57 <col>
  58 <col>
  59 <col>
  60 </colgroup>
  61 <thead><tr>
  62 <th>
  63                   <p>
  64                     Type
  65                   </p>
  66                 </th>
  67 <th>
  68                   <p>
  69                     Concept
  70                   </p>
  71                 </th>
  72 <th>
  73                   <p>
  74                     Name
  75                   </p>
  76                 </th>
  77 <th>
  78                   <p>
  79                     Description
  80                   </p>
  81                 </th>
  82 </tr></thead>
  83 <tbody>
  84 <tr>
  85 <td>
  86                   <p>
  87                     Geometry const &amp;
  88                   </p>
  89                 </td>
  90 <td>
  91                   <p>
  92                     the input geometry type
  93                   </p>
  94                 </td>
  95 <td>
  96                   <p>
  97                     geometry
  98                   </p>
  99                 </td>
 100 <td>
 101                   <p>
 102                     A model of the specified concept, input geometry
 103                   </p>
 104                 </td>
 105 </tr>
 106 <tr>
 107 <td>
 108                   <p>
 109                     OutputGeometry &amp;
 110                   </p>
 111                 </td>
 112 <td>
 113                   <p>
 114                     the output geometry type
 115                   </p>
 116                 </td>
 117 <td>
 118                   <p>
 119                     hull
 120                   </p>
 121                 </td>
 122 <td>
 123                   <p>
 124                     A model of the specified concept which is set to the convex hull
 125                   </p>
 126                 </td>
 127 </tr>
 128 </tbody>
 129 </table></div>
 130 <h6>
 131 <a name="geometry.reference.algorithms.convex_hull.h3"></a>
 132           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.header"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.header">Header</a>
 133         </h6>
 134 <p>
 135           Either
 136         </p>
 137 <p>
 138           <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">hpp</span><span class="special">&gt;</span></code>
 139         </p>
 140 <p>
 141           Or
 142         </p>
 143 <p>
 144           <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>
 145         </p>
 146 <h6>
 147 <a name="geometry.reference.algorithms.convex_hull.h4"></a>
 148           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.conformance"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.conformance">Conformance</a>
 149         </h6>
 150 <p>
 151           The function convex_hull implements function ConvexHull() from the <a href="http://www.opengeospatial.org/standards/sfa" target="_top">OGC Simple Feature Specification</a>.
 152         </p>
 153 <h6>
 154 <a name="geometry.reference.algorithms.convex_hull.h5"></a>
 155           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.supported_geometries"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.supported_geometries">Supported
 156           geometries</a>
 157         </h6>
 158 <div class="informaltable"><table class="table">
 159 <colgroup>
 160 <col>
 161 <col>
 162 </colgroup>
 163 <thead><tr>
 164 <th>
 165                   <p>
 166                     Geometry
 167                   </p>
 168                 </th>
 169 <th>
 170                   <p>
 171                     Status
 172                   </p>
 173                 </th>
 174 </tr></thead>
 175 <tbody>
 176 <tr>
 177 <td>
 178                   <p>
 179                     Point
 180                   </p>
 181                 </td>
 182 <td>
 183                   <p>
 184                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 185                   </p>
 186                 </td>
 187 </tr>
 188 <tr>
 189 <td>
 190                   <p>
 191                     Segment
 192                   </p>
 193                 </td>
 194 <td>
 195                   <p>
 196                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 197                   </p>
 198                 </td>
 199 </tr>
 200 <tr>
 201 <td>
 202                   <p>
 203                     Box
 204                   </p>
 205                 </td>
 206 <td>
 207                   <p>
 208                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 209                   </p>
 210                 </td>
 211 </tr>
 212 <tr>
 213 <td>
 214                   <p>
 215                     Linestring
 216                   </p>
 217                 </td>
 218 <td>
 219                   <p>
 220                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 221                   </p>
 222                 </td>
 223 </tr>
 224 <tr>
 225 <td>
 226                   <p>
 227                     Ring
 228                   </p>
 229                 </td>
 230 <td>
 231                   <p>
 232                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 233                   </p>
 234                 </td>
 235 </tr>
 236 <tr>
 237 <td>
 238                   <p>
 239                     Polygon
 240                   </p>
 241                 </td>
 242 <td>
 243                   <p>
 244                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 245                   </p>
 246                 </td>
 247 </tr>
 248 <tr>
 249 <td>
 250                   <p>
 251                     MultiPoint
 252                   </p>
 253                 </td>
 254 <td>
 255                   <p>
 256                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 257                   </p>
 258                 </td>
 259 </tr>
 260 <tr>
 261 <td>
 262                   <p>
 263                     MultiLinestring
 264                   </p>
 265                 </td>
 266 <td>
 267                   <p>
 268                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 269                   </p>
 270                 </td>
 271 </tr>
 272 <tr>
 273 <td>
 274                   <p>
 275                     MultiPolygon
 276                   </p>
 277                 </td>
 278 <td>
 279                   <p>
 280                     <span class="inlinemediaobject"><img src="../../../img/ok.png" alt="ok"></span>
 281                   </p>
 282                 </td>
 283 </tr>
 284 </tbody>
 285 </table></div>
 286 <h6>
 287 <a name="geometry.reference.algorithms.convex_hull.h6"></a>
 288           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.complexity"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.complexity">Complexity</a>
 289         </h6>
 290 <p>
 291           Linearithmic
 292         </p>
 293 <h6>
 294 <a name="geometry.reference.algorithms.convex_hull.h7"></a>
 295           <span class="phrase"><a name="geometry.reference.algorithms.convex_hull.example"></a></span><a class="link" href="convex_hull.html#geometry.reference.algorithms.convex_hull.example">Example</a>
 296         </h6>
 297 <p>
 298           Shows how to generate the convex_hull of a geometry
 299         </p>
 300 <p>
 301 </p>
 302 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
 303
 304 <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>
 305 <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>
 306 <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>
 307
 308 <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>
 309
 310
 311 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
 312 <span class="special">{</span>
 313     <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>
 314     <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>
 315
 316     <span class="identifier">polygon</span> <span class="identifier">poly</span><span class="special">;</span>
 317     <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>
 318         <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>
 319
 320     <span class="identifier">polygon</span> <span class="identifier">hull</span><span class="special">;</span>
 321     <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>
 322
 323     <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>
 324     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span>
 325         <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>
 326         <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>
 327         <span class="special">;</span>
 328
 329
 330     <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 331 <span class="special">}</span>
 332 </pre>
 333 <p>
 334         </p>
 335 <p>
 336           Output:
 337         </p>
 338 <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)))
 339 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)))
 340
 341 <img src="../../../img/algorithms/convex_hull.png" alt="convex_hull">
 342 </pre>
 343 </div>
 344 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 345 <td align="left"></td>
 346 <td align="right"><div class="copyright-footer">Copyright &#169; 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam
 347       Wulkiewicz, Oracle and/or its affiliates<p>
 348         Distributed under the Boost Software License, Version 1.0. (See accompanying
 349         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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