libs/geometry/doc/doxy/doxygen_output/html_by_doxygen/c04_b_custom_triangle_example_8cpp-example.html

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  39 <div class="title">c04_b_custom_triangle_example.cpp</div>  </div>
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  41 <div class="contents">
  42 <p>This second custom triangle example shows an alternative implementation for a custom shape, showing a partial specialization for the area calculation.</p>
  43 <div class="fragment"><div class="line"><span class="comment">// Boost.Geometry (aka GGL, Generic Geometry Library)</span></div>
  44 <div class="line"></div>
  45 <div class="line"><span class="comment">// Copyright (c) 2007-2012 Barend Gehrels, Amsterdam, the Netherlands.</span></div>
  46 <div class="line"><span class="comment">// Copyright (c) 2008-2012 Bruno Lalande, Paris, France.</span></div>
  47 <div class="line"><span class="comment">// Copyright (c) 2009-2012 Mateusz Loskot, London, UK.</span></div>
  48 <div class="line"></div>
  49 <div class="line"><span class="comment">// Use, modification and distribution is subject to the Boost Software License,</span></div>
  50 <div class="line"><span class="comment">// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at</span></div>
  51 <div class="line"><span class="comment">// http://www.boost.org/LICENSE_1_0.txt)</span></div>
  52 <div class="line"><span class="comment">//</span></div>
  53 <div class="line"><span class="comment">// Custom triangle template Example</span></div>
  54 <div class="line"></div>
  55 <div class="line"><span class="preprocessor">#include &lt;iostream&gt;</span></div>
  56 <div class="line"></div>
  57 <div class="line"><span class="preprocessor">#include &lt;boost/array.hpp&gt;</span></div>
  58 <div class="line"><span class="preprocessor">#include &lt;boost/tuple/tuple.hpp&gt;</span></div>
  59 <div class="line"></div>
  60 <div class="line"><span class="preprocessor">#include &lt;<a class="code" href="algorithms_2area_8hpp.html">boost/geometry/algorithms/area.hpp</a>&gt;</span></div>
  61 <div class="line"><span class="preprocessor">#include &lt;<a class="code" href="algorithms_2centroid_8hpp.html">boost/geometry/algorithms/centroid.hpp</a>&gt;</span></div>
  62 <div class="line"><span class="preprocessor">#include &lt;<a class="code" href="boost__tuple_8hpp.html">boost/geometry/geometries/adapted/boost_tuple.hpp</a>&gt;</span></div>
  63 <div class="line"><span class="preprocessor">#include &lt;<a class="code" href="geometries_2register_2ring_8hpp.html">boost/geometry/geometries/register/ring.hpp</a>&gt;</span></div>
  64 <div class="line"><span class="preprocessor">#include &lt;<a class="code" href="strategies_8hpp.html">boost/geometry/strategies/strategies.hpp</a>&gt;</span></div>
  65 <div class="line"><span class="preprocessor">#include &lt;boost/geometry/io/dsv/write.hpp&gt;</span></div>
  66 <div class="line"></div>
  67 <div class="line"><a name="a0"></a><a class="code" href="boost__tuple_8hpp.html#ad912721c6dfdc38ab2cd6551c2436f97">BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS</a>(cs::cartesian)</div>
  68 <div class="line"></div>
  69 <div class="line"></div>
  70 <div class="line">template &lt;typename P&gt;</div>
  71 <div class="line">struct triangle : public boost::array&lt;P, 3&gt;</div>
  72 <div class="line">{</div>
  73 <div class="line">};</div>
  74 <div class="line"></div>
  75 <div class="line"></div>
  76 <div class="line"><span class="comment">// Register triangle&lt;P&gt; as a ring</span></div>
  77 <div class="line"><a name="a1"></a><a class="code" href="group__register.html#ga8a9071c3e9e9e0175250677a50e3fcc8">BOOST_GEOMETRY_REGISTER_RING_TEMPLATED</a>(triangle)</div>
  78 <div class="line"></div>
  79 <div class="line"></div>
  80 <div class="line">namespace boost { <span class="keyword">namespace </span>geometry { <span class="keyword">namespace </span>dispatch {</div>
  81 <div class="line"></div>
  82 <div class="line"><span class="comment">// Specializations of area dispatch structure, implement algorithm</span></div>
  83 <div class="line"><span class="keyword">template</span>&lt;<span class="keyword">typename</span> Po<span class="keywordtype">int</span>&gt;</div>
  84 <div class="line"><span class="keyword">struct </span><a name="a2"></a><a class="code" href="group__area.html#gaf7a1c34467f74f290d0b090adb27db62">area</a>&lt;triangle&lt;Point&gt;, ring_tag&gt;</div>
  85 <div class="line">{</div>
  86 <div class="line">    <span class="keyword">template</span> &lt;<span class="keyword">typename</span> Strategy&gt;</div>
  87 <div class="line">    <span class="keyword">static</span> <span class="keyword">inline</span> <span class="keywordtype">double</span> apply(triangle&lt;Point&gt; <span class="keyword">const</span>&amp; t, Strategy <span class="keyword">const</span>&amp;)</div>
  88 <div class="line">    {</div>
  89 <div class="line">        <span class="keywordflow">return</span> 0.5  * ((get&lt;0&gt;(t[1]) - get&lt;0&gt;(t[0])) * (get&lt;1&gt;(t[2]) - get&lt;1&gt;(t[0]))</div>
  90 <div class="line">                     - (get&lt;0&gt;(t[2]) - get&lt;0&gt;(t[0])) * (get&lt;1&gt;(t[1]) - get&lt;1&gt;(t[0])));</div>
  91 <div class="line">    }</div>
  92 <div class="line">};</div>
  93 <div class="line"></div>
  94 <div class="line">}}} <span class="comment">// namespace boost::geometry::dispatch</span></div>
  95 <div class="line"></div>
  96 <div class="line"></div>
  97 <div class="line"><span class="keywordtype">int</span> main()</div>
  98 <div class="line">{</div>
  99 <div class="line">    <span class="comment">//triangle&lt;boost::geometry::point_xy&lt;double&gt; &gt; t;</span></div>
 100 <div class="line">    triangle&lt;boost::tuple&lt;double, double&gt; &gt; t;</div>
 101 <div class="line">    t[0] = boost::make_tuple(0, 0);</div>
 102 <div class="line">    t[1] = boost::make_tuple(5, 0);</div>
 103 <div class="line">    t[2] = boost::make_tuple(2.5, 2.5);</div>
 104 <div class="line"></div>
 105 <div class="line">    std::cout &lt;&lt; <span class="stringliteral">&quot;Triangle: &quot;</span> &lt;&lt; boost::geometry::dsv(t) &lt;&lt; std::endl;</div>
 106 <div class="line">    std::cout &lt;&lt; <span class="stringliteral">&quot;Area: &quot;</span> &lt;&lt; <a class="code" href="group__area.html#gaf7a1c34467f74f290d0b090adb27db62">boost::geometry::area</a>(t) &lt;&lt; std::endl;</div>
 107 <div class="line"></div>
 108 <div class="line">    <span class="comment">//boost::geometry::point_xy&lt;double&gt; c;</span></div>
 109 <div class="line">    boost::tuple&lt;double, double&gt; c;</div>
 110 <div class="line">    <a name="a3"></a><a class="code" href="group__centroid.html#ga3ec2c5e245c42ffaf28f1c88ea564c8c">boost::geometry::centroid</a>(t, c);</div>
 111 <div class="line">    std::cout &lt;&lt; <span class="stringliteral">&quot;Centroid: &quot;</span> &lt;&lt; boost::geometry::dsv(c) &lt;&lt; std::endl;</div>
 112 <div class="line"></div>
 113 <div class="line">    <span class="keywordflow">return</span> 0;</div>
 114 <div class="line">}</div>
 115 </div><!-- fragment --> </div><!-- contents -->
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 121 <p>April 2, 2011</p>
 122 </small></td>
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 124 <small>
 125 Copyright &copy; 2007-2011 Barend Gehrels, Amsterdam, the Netherlands<br>
 126 Copyright &copy; 2008-2011 Bruno Lalande, Paris, France<br>
 127 Copyright &copy; 2009-2010 Mateusz Loskot, London, UK<br>
 128 </small>
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