ceph/src/boost/libs/graph/include/boost/graph/circle_layout.hpp

   1 // Copyright 2004 The Trustees of Indiana University.
   2
   3 // Distributed under the Boost Software License, Version 1.0.
   4 // (See accompanying file LICENSE_1_0.txt or copy at
   5 // http://www.boost.org/LICENSE_1_0.txt)
   6
   7 //  Authors: Douglas Gregor
   8 //           Andrew Lumsdaine
   9 #ifndef BOOST_GRAPH_CIRCLE_LAYOUT_HPP
  10 #define BOOST_GRAPH_CIRCLE_LAYOUT_HPP
  11 #include <boost/config/no_tr1/cmath.hpp>
  12 #include <boost/math/constants/constants.hpp>
  13 #include <utility>
  14 #include <boost/graph/graph_traits.hpp>
  15 #include <boost/graph/iteration_macros.hpp>
  16 #include <boost/graph/topology.hpp>
  17 #include <boost/static_assert.hpp>
  18
  19 namespace boost {
  20   /**
  21    * \brief Layout the graph with the vertices at the points of a regular
  22    * n-polygon.
  23    *
  24    * The distance from the center of the polygon to each point is
  25    * determined by the @p radius parameter. The @p position parameter
  26    * must be an Lvalue Property Map whose value type is a class type
  27    * containing @c x and @c y members that will be set to the @c x and
  28    * @c y coordinates.
  29    */
  30   template<typename VertexListGraph, typename PositionMap, typename Radius>
  31   void
  32   circle_graph_layout(const VertexListGraph& g, PositionMap position,
  33                       Radius radius)
  34   {
  35     BOOST_STATIC_ASSERT (property_traits<PositionMap>::value_type::dimensions >= 2);
  36     const double pi = boost::math::constants::pi<double>();
  37
  38 #ifndef BOOST_NO_STDC_NAMESPACE
  39     using std::sin;
  40     using std::cos;
  41 #endif // BOOST_NO_STDC_NAMESPACE
  42
  43     typedef typename graph_traits<VertexListGraph>::vertices_size_type
  44       vertices_size_type;
  45
  46     vertices_size_type n = num_vertices(g);
  47
  48     vertices_size_type i = 0;
  49     double two_pi_over_n = 2. * pi / n;
  50     BGL_FORALL_VERTICES_T(v, g, VertexListGraph) {
  51       position[v][0] = radius * cos(i * two_pi_over_n);
  52       position[v][1] = radius * sin(i * two_pi_over_n);
  53       ++i;
  54     }
  55   }
  56 } // end namespace boost
  57
  58 #endif // BOOST_GRAPH_CIRCLE_LAYOUT_HPP