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 <cmath>

    12 #include <utility>

    13 #include <boost/graph/graph_traits.hpp>

    14 

    15 namespace boost {

    16   /** 

    17    * \brief Layout the graph with the vertices at the points of a regular

    18    * n-polygon. 

    19    *

    20    * The distance from the center of the polygon to each point is

    21    * determined by the @p radius parameter. The @p position parameter

    22    * must be an Lvalue Property Map whose value type is a class type

    23    * containing @c x and @c y members that will be set to the @c x and

    24    * @c y coordinates.

    25    */

    26   template<typename VertexListGraph, typename PositionMap, typename Radius>

    27   void 

    28   circle_graph_layout(const VertexListGraph& g, PositionMap position,

    29                       Radius radius)

    30   {

    31     const double pi = 3.14159;

    32 

    33 #ifndef BOOST_NO_STDC_NAMESPACE

    34     using std::sin;

    35     using std::cos;

    36 #endif // BOOST_NO_STDC_NAMESPACE

    37 

    38     typedef typename graph_traits<VertexListGraph>::vertices_size_type 

    39       vertices_size_type;

    40 

    41     vertices_size_type n = num_vertices(g);

    42     

    43     typedef typename graph_traits<VertexListGraph>::vertex_iterator 

    44       vertex_iterator;

    45 

    46     vertices_size_type i = 0;

    47     for(std::pair<vertex_iterator, vertex_iterator> v = vertices(g); 

    48         v.first != v.second; ++v.first, ++i) {

    49       position[*v.first].x = radius * cos(i * 2 * pi / n);

    50       position[*v.first].y = radius * sin(i * 2 * pi / n);

    51     }

    52   }

    53 } // end namespace boost

    54 

    55 #endif // BOOST_GRAPH_CIRCLE_LAYOUT_HPP