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  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3"></a><a class="link" href="line_interpolate_3.html" title="line_interpolate">line_interpolate</a>
  28 </h5></div></div></div>
  29 <p>
  30             <a class="indexterm" name="idm46186994742352"></a>
  31 Returns one or more points interpolated along a LineString.
  32           </p>
  33 <h6>
  34 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.h0"></a>
  35             <span class="phrase"><a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.synopsis"></a></span><a class="link" href="line_interpolate_3.html#geometry.reference.algorithms.line_interpolate.line_interpolate_3.synopsis">Synopsis</a>
  36           </h6>
  37 <p>
  38 </p>
  39 <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">Distance</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Pointlike</span><span class="special">&gt;</span>
  40 <span class="keyword">void</span> <span class="identifier">line_interpolate</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">Distance</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">max_distance</span><span class="special">,</span> <span class="identifier">Pointlike</span> <span class="special">&amp;</span> <span class="identifier">pointlike</span><span class="special">)</span></pre>
  41 <p>
  42           </p>
  43 <h6>
  44 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.h1"></a>
  45             <span class="phrase"><a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.parameters"></a></span><a class="link" href="line_interpolate_3.html#geometry.reference.algorithms.line_interpolate.line_interpolate_3.parameters">Parameters</a>
  46           </h6>
  47 <div class="informaltable"><table class="table">
  48 <colgroup>
  49 <col>
  50 <col>
  51 <col>
  52 <col>
  53 </colgroup>
  54 <thead><tr>
  55 <th>
  56                     <p>
  57                       Type
  58                     </p>
  59                   </th>
  60 <th>
  61                     <p>
  62                       Concept
  63                     </p>
  64                   </th>
  65 <th>
  66                     <p>
  67                       Name
  68                     </p>
  69                   </th>
  70 <th>
  71                     <p>
  72                       Description
  73                     </p>
  74                   </th>
  75 </tr></thead>
  76 <tbody>
  77 <tr>
  78 <td>
  79                     <p>
  80                       Geometry const &amp;
  81                     </p>
  82                   </td>
  83 <td>
  84                     <p>
  85                       Any type fulfilling a LineString concept
  86                     </p>
  87                   </td>
  88 <td>
  89                     <p>
  90                       geometry
  91                     </p>
  92                   </td>
  93 <td>
  94                     <p>
  95                       Input geometry
  96                     </p>
  97                   </td>
  98 </tr>
  99 <tr>
 100 <td>
 101                     <p>
 102                       Distance const &amp;
 103                     </p>
 104                   </td>
 105 <td>
 106                     <p>
 107                       A numerical distance measure
 108                     </p>
 109                   </td>
 110 <td>
 111                     <p>
 112                       max_distance
 113                     </p>
 114                   </td>
 115 <td>
 116                     <p>
 117                       Distance threshold (in units depending on coordinate system)
 118                       representing the spacing between the points
 119                     </p>
 120                   </td>
 121 </tr>
 122 <tr>
 123 <td>
 124                     <p>
 125                       Pointlike &amp;
 126                     </p>
 127                   </td>
 128 <td>
 129                     <p>
 130                       Any type fulfilling Point or Multipoint concept
 131                     </p>
 132                   </td>
 133 <td>
 134                     <p>
 135                       pointlike
 136                     </p>
 137                   </td>
 138 <td>
 139                     <p>
 140                       Output: either a Point (exactly one point will be constructed)
 141                       or a MultiPoint (depending on the max_distance one or more
 142                       points will be constructed)
 143                     </p>
 144                   </td>
 145 </tr>
 146 </tbody>
 147 </table></div>
 148 <h6>
 149 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.h2"></a>
 150             <span class="phrase"><a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.header"></a></span><a class="link" href="line_interpolate_3.html#geometry.reference.algorithms.line_interpolate.line_interpolate_3.header">Header</a>
 151           </h6>
 152 <p>
 153             Either
 154           </p>
 155 <p>
 156             <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>
 157           </p>
 158 <p>
 159             Or
 160           </p>
 161 <p>
 162             <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">line_interpolate</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 163           </p>
 164 <h6>
 165 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.h3"></a>
 166             <span class="phrase"><a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.conformance"></a></span><a class="link" href="line_interpolate_3.html#geometry.reference.algorithms.line_interpolate.line_interpolate_3.conformance">Conformance</a>
 167           </h6>
 168 <p>
 169             The function line_interpolate_point is not defined by OGC.
 170           </p>
 171 <div class="note"><table border="0" summary="Note">
 172 <tr>
 173 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../../doc/src/images/note.png"></td>
 174 <th align="left">Note</th>
 175 </tr>
 176 <tr><td align="left" valign="top"><p>
 177               PostGIS contains an algorithm ST_LineInterpolatePoints with similar
 178               functionality. See the <a href="https://postgis.net/docs/ST_LineInterpolatePoints.html" target="_top">PostGIS
 179               documentation</a>.
 180             </p></td></tr>
 181 </table></div>
 182 <h6>
 183 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.h4"></a>
 184             <span class="phrase"><a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.behavior"></a></span><a class="link" href="line_interpolate_3.html#geometry.reference.algorithms.line_interpolate.line_interpolate_3.behavior">Behavior</a>
 185           </h6>
 186 <p>
 187             The algorithm iterates among segments of the linestring and computes
 188             interpolation points if needed.
 189           </p>
 190 <h6>
 191 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.h5"></a>
 192             <span class="phrase"><a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.example"></a></span><a class="link" href="line_interpolate_3.html#geometry.reference.algorithms.line_interpolate.line_interpolate_3.example">Example</a>
 193           </h6>
 194 <p>
 195             Shows how to interpolate points on a linestring
 196           </p>
 197 <p>
 198 </p>
 199 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
 200
 201 <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>
 202 <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">point_xy</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 203
 204 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">;</span>
 205
 206 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
 207 <span class="special">{</span>
 208     <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">d2</span><span class="special">::</span><span class="identifier">point_xy</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="identifier">point_type</span><span class="special">;</span>
 209     <span class="keyword">using</span> <span class="identifier">segment_type</span> <span class="special">=</span> <span class="identifier">model</span><span class="special">::</span><span class="identifier">segment</span><span class="special">&lt;</span><span class="identifier">point_type</span><span class="special">&gt;;</span>
 210     <span class="keyword">using</span> <span class="identifier">linestring_type</span> <span class="special">=</span> <span class="identifier">model</span><span class="special">::</span><span class="identifier">linestring</span><span class="special">&lt;</span><span class="identifier">point_type</span><span class="special">&gt;;</span>
 211     <span class="keyword">using</span> <span class="identifier">multipoint_type</span> <span class="special">=</span> <span class="identifier">model</span><span class="special">::</span><span class="identifier">multi_point</span><span class="special">&lt;</span><span class="identifier">point_type</span><span class="special">&gt;;</span>
 212
 213     <span class="identifier">segment_type</span> <span class="keyword">const</span> <span class="identifier">s</span> <span class="special">{</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="special">{</span><span class="number">1</span><span class="special">,</span> <span class="number">1</span><span class="special">}</span> <span class="special">};</span>
 214     <span class="identifier">linestring_type</span> <span class="keyword">const</span> <span class="identifier">l</span> <span class="special">{</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="special">{</span><span class="number">1</span><span class="special">,</span> <span class="number">0</span><span class="special">},</span> <span class="special">{</span><span class="number">1</span><span class="special">,</span> <span class="number">1</span><span class="special">},</span> <span class="special">{</span><span class="number">0</span><span class="special">,</span> <span class="number">1</span><span class="special">},</span> <span class="special">{</span><span class="number">0</span><span class="special">,</span> <span class="number">2</span><span class="special">}</span> <span class="special">};</span>
 215     <span class="identifier">point_type</span> <span class="identifier">p</span><span class="special">;</span>
 216     <span class="identifier">multipoint_type</span> <span class="identifier">mp</span><span class="special">;</span>
 217
 218     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"point interpolation"</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>
 219
 220     <span class="identifier">line_interpolate</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">sqrt</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="identifier">p</span><span class="special">);</span>
 221     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"on segment : "</span> <span class="special">&lt;&lt;</span> <span class="identifier">wkt</span><span class="special">(</span><span class="identifier">p</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>
 222
 223     <span class="identifier">line_interpolate</span><span class="special">(</span><span class="identifier">l</span><span class="special">,</span> <span class="number">1.4</span><span class="special">,</span> <span class="identifier">p</span><span class="special">);</span>
 224     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"on linestring : "</span> <span class="special">&lt;&lt;</span> <span class="identifier">wkt</span><span class="special">(</span><span class="identifier">p</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="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 225
 226     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"multipoint interpolation"</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>
 227
 228     <span class="identifier">line_interpolate</span><span class="special">(</span><span class="identifier">s</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">sqrt</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="identifier">mp</span><span class="special">);</span>
 229     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"on segment : "</span> <span class="special">&lt;&lt;</span> <span class="identifier">wkt</span><span class="special">(</span><span class="identifier">mp</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>
 230
 231     <span class="identifier">mp</span><span class="special">=</span><span class="identifier">multipoint_type</span><span class="special">();</span>
 232     <span class="identifier">line_interpolate</span><span class="special">(</span><span class="identifier">l</span><span class="special">,</span> <span class="number">1.4</span><span class="special">,</span> <span class="identifier">mp</span><span class="special">);</span>
 233     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"on linestring : "</span> <span class="special">&lt;&lt;</span> <span class="identifier">wkt</span><span class="special">(</span><span class="identifier">mp</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>
 234
 235     <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 236 <span class="special">}</span>
 237 </pre>
 238 <p>
 239           </p>
 240 <p>
 241             Output:
 242           </p>
 243 <pre class="programlisting">point interpolation
 244 on segment : POINT(0.25 0.25)
 245 on linestring : POINT(1 0.4)
 246
 247 multipoint interpolation
 248 on segment : MULTIPOINT((0.25 0.25),(0.5 0.5),(0.75 0.75),(1 1))
 249 on linestring : MULTIPOINT((1 0.4),(0.2 1))
 250 </pre>
 251 <h6>
 252 <a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.h6"></a>
 253             <span class="phrase"><a name="geometry.reference.algorithms.line_interpolate.line_interpolate_3.see_also"></a></span><a class="link" href="line_interpolate_3.html#geometry.reference.algorithms.line_interpolate.line_interpolate_3.see_also">See
 254             also</a>
 255           </h6>
 256 <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
 257                 <a class="link" href="../densify.html" title="densify">densify</a>
 258               </li></ul></div>
 259 </div>
 260 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 261 <td align="left"></td>
 262 <td align="right"><div class="copyright-footer">Copyright &#169; 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam
 263       Wulkiewicz, Oracle and/or its affiliates<p>
 264         Distributed under the Boost Software License, Version 1.0. (See accompanying
 265         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>)
 266       </p>
 267 </div></td>
 268 </tr></table>
 269 <hr>
 270 <div class="spirit-nav">
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