Chris@16: // Copyright 2004 The Trustees of Indiana University.
Chris@16: 
Chris@16: // Distributed under the Boost Software License, Version 1.0.
Chris@16: // (See accompanying file LICENSE_1_0.txt or copy at
Chris@16: // http://www.boost.org/LICENSE_1_0.txt)
Chris@16: 
Chris@16: //  Authors: Douglas Gregor
Chris@16: //           Andrew Lumsdaine
Chris@16: #ifndef BOOST_GRAPH_CIRCLE_LAYOUT_HPP
Chris@16: #define BOOST_GRAPH_CIRCLE_LAYOUT_HPP
Chris@16: #include <boost/config/no_tr1/cmath.hpp>
Chris@16: #include <boost/math/constants/constants.hpp>
Chris@16: #include <utility>
Chris@16: #include <boost/graph/graph_traits.hpp>
Chris@16: #include <boost/graph/iteration_macros.hpp>
Chris@16: #include <boost/graph/topology.hpp>
Chris@16: #include <boost/static_assert.hpp>
Chris@16: 
Chris@16: namespace boost {
Chris@16:   /** 
Chris@16:    * \brief Layout the graph with the vertices at the points of a regular
Chris@16:    * n-polygon. 
Chris@16:    *
Chris@16:    * The distance from the center of the polygon to each point is
Chris@16:    * determined by the @p radius parameter. The @p position parameter
Chris@16:    * must be an Lvalue Property Map whose value type is a class type
Chris@16:    * containing @c x and @c y members that will be set to the @c x and
Chris@16:    * @c y coordinates.
Chris@16:    */
Chris@16:   template<typename VertexListGraph, typename PositionMap, typename Radius>
Chris@16:   void 
Chris@16:   circle_graph_layout(const VertexListGraph& g, PositionMap position,
Chris@16:                       Radius radius)
Chris@16:   {
Chris@16:     BOOST_STATIC_ASSERT (property_traits<PositionMap>::value_type::dimensions >= 2);
Chris@16:     const double pi = boost::math::constants::pi<double>();
Chris@16: 
Chris@16: #ifndef BOOST_NO_STDC_NAMESPACE
Chris@16:     using std::sin;
Chris@16:     using std::cos;
Chris@16: #endif // BOOST_NO_STDC_NAMESPACE
Chris@16: 
Chris@16:     typedef typename graph_traits<VertexListGraph>::vertices_size_type 
Chris@16:       vertices_size_type;
Chris@16: 
Chris@16:     vertices_size_type n = num_vertices(g);
Chris@16:     
Chris@16:     vertices_size_type i = 0;
Chris@16:     double two_pi_over_n = 2. * pi / n;
Chris@16:     BGL_FORALL_VERTICES_T(v, g, VertexListGraph) {
Chris@16:       position[v][0] = radius * cos(i * two_pi_over_n);
Chris@16:       position[v][1] = radius * sin(i * two_pi_over_n);
Chris@16:       ++i;
Chris@16:     }
Chris@16:   }
Chris@16: } // end namespace boost
Chris@16: 
Chris@16: #endif // BOOST_GRAPH_CIRCLE_LAYOUT_HPP