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3rdparty/boost_1_81_0/boost/graph/circle_layout.hpp 1.88 KB
63e88f80   Hu Chunming   提交三方库
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  // Copyright 2004 The Trustees of Indiana University.
  
  // Distributed under the Boost Software License, Version 1.0.
  // (See accompanying file LICENSE_1_0.txt or copy at
  // http://www.boost.org/LICENSE_1_0.txt)
  
  //  Authors: Douglas Gregor
  //           Andrew Lumsdaine
  #ifndef BOOST_GRAPH_CIRCLE_LAYOUT_HPP
  #define BOOST_GRAPH_CIRCLE_LAYOUT_HPP
  #include <boost/config/no_tr1/cmath.hpp>
  #include <boost/math/constants/constants.hpp>
  #include <utility>
  #include <boost/graph/graph_traits.hpp>
  #include <boost/graph/iteration_macros.hpp>
  #include <boost/graph/topology.hpp>
  #include <boost/static_assert.hpp>
  
  namespace boost
  {
  /**
   * \brief Layout the graph with the vertices at the points of a regular
   * n-polygon.
   *
   * The distance from the center of the polygon to each point is
   * determined by the @p radius parameter. The @p position parameter
   * must be an Lvalue Property Map whose value type is a class type
   * containing @c x and @c y members that will be set to the @c x and
   * @c y coordinates.
   */
  template < typename VertexListGraph, typename PositionMap, typename Radius >
  void circle_graph_layout(
      const VertexListGraph& g, PositionMap position, Radius radius)
  {
      BOOST_STATIC_ASSERT(
          property_traits< PositionMap >::value_type::dimensions >= 2);
      const double pi = boost::math::constants::pi< double >();
  
  #ifndef BOOST_NO_STDC_NAMESPACE
      using std::cos;
      using std::sin;
  #endif // BOOST_NO_STDC_NAMESPACE
  
      typedef typename graph_traits< VertexListGraph >::vertices_size_type
          vertices_size_type;
  
      vertices_size_type n = num_vertices(g);
  
      vertices_size_type i = 0;
      double two_pi_over_n = 2. * pi / n;
      BGL_FORALL_VERTICES_T(v, g, VertexListGraph)
      {
          position[v][0] = radius * cos(i * two_pi_over_n);
          position[v][1] = radius * sin(i * two_pi_over_n);
          ++i;
      }
  }
  } // end namespace boost
  
  #endif // BOOST_GRAPH_CIRCLE_LAYOUT_HPP