cgal/Arrangement_2/include/CGAL/Arr_overlay.h

// Copyright (c) 2005  Tel-Aviv University (Israel).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you may redistribute it under
// the terms of the Q Public License version 1.0.
// See the file LICENSE.QPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
// 
//
// Author(s)     : Baruch Zukerman <baruchzu@post.tau.ac.il>

#ifndef CGAL_ARR_OVERLAY_H
#define CGAL_ARR_OVERLAY_H

#include <CGAL/Arrangement_2.h>
#include <CGAL/Sweep_line_2.h>
#include <CGAL/Sweep_line_2/Arr_construction_event.h>
#include <CGAL/Arr_overlay_2/Overlay_subcurve.h>
#include <CGAL/Arr_overlay_2/Overlay_visitor.h>
#include <CGAL/Arr_overlay_2/Overlay_meta_traits.h>
#include <CGAL/Arr_overlay_2/Edge_iterator_adaptor.h>
#include <CGAL/Object.h>

#include <vector>

CGAL_BEGIN_NAMESPACE

/*!
 * Compute the overlay of two input arrangements.
 * \param arr1 The first arrangement.
 * \param arr2 The second arrangement.
 * \param res Output: The resulting arrangement.
 * \param traits An overlay-traits class. As arr1, arr2 and res are all
 *               templated with the same arrangement-traits class but with
 *               different DCELs, the overlay-traits class defines the
 *               various overlay operations of pairs of DCEL features from
 *               Dcel1 and Dcel2 to the resulting ResDcel.
 */
template <class Traits_,
          class Dcel1,
          class Dcel2,
          class ResDcel,
          class OverlayTraits >
void overlay (const Arrangement_2<Traits_, Dcel1>& arr1,
              const Arrangement_2<Traits_, Dcel2>& arr2,
              Arrangement_2<Traits_, ResDcel>& res,
              OverlayTraits& traits)
{
  typedef Traits_                                     Base_Traits;
  typedef typename Base_Traits::X_monotone_curve_2    Base_X_monotone_curve_2;

  typedef Arrangement_2<Traits_, Dcel1>               Arrangement1;
  typedef Arrangement_2<Traits_, Dcel2>               Arrangement2;
  typedef Arrangement_2<Traits_, ResDcel>             Res_Arrangement;

  typedef typename Arrangement1::Halfedge_const_handle       
                                                      Halfedge_const_handle_1;
  typedef typename Arrangement1::Edge_const_iterator         
                                                      Edge_const_iterator_1;
  typedef typename Arrangement1::Face_const_handle
                                                      Face_handle1;


  typedef typename Arrangement2::Halfedge_const_handle       
                                                      Halfedge_const_handle_2;
  typedef typename Arrangement2::Edge_const_iterator  
                                                      Edge_const_iterator_2;
  typedef typename Arrangement2::Face_const_handle    
                                                      Face_handle2;

  typedef typename Res_Arrangement::Halfedge_handle   Halfedge_handle_res;

  // in order to iterate over isolated vertices
  typedef typename Arrangement1::Vertex_const_iterator
                                                      Vertex_const_iterator_1;

  typedef typename Arrangement2::Vertex_const_iterator
                                                      Vertex_const_iterator_2;

  typedef Overlay_meta_traits<Base_Traits,
                              Arrangement1,
                              Arrangement2>            Traits;

  typedef typename Traits::X_monotone_curve_2          X_monotone_curve_2;
  typedef typename Traits::Point_2                     Point_2;

  typedef Overlay_subcurve<Traits>  Subcurve;
  typedef Arr_construction_event<Traits,
                                 Subcurve,
                                 Halfedge_handle_res > Event;
  typedef Overlay_visitor<Traits,
                          Arrangement1,
                          Arrangement2,
                          Res_Arrangement,
                          Event,
                          Subcurve,
                          OverlayTraits>               Visitor;

  typedef Sweep_line_2<Traits,
                       Visitor,
                       Subcurve,
                       Event>                          Sweep_line;


    
  //the res arrangement can't be the same one as one as the input arrangement
  CGAL_precondition(((void *)(&res) != (void *)(&arr1)) && 
                    ((void *)(&res) != (void *)(&arr2)));

  
  typedef Edge_iterator_adaptor<Base_X_monotone_curve_2,
                                X_monotone_curve_2,
                                Arrangement1,
                                Arrangement2>    Edge_iterator_adaptor;

  Edge_iterator_adaptor begin(arr1.edges_begin(), arr1.edges_end(), 
                              arr2.edges_begin());
  Edge_iterator_adaptor end(arr2.edges_end());


  if(!arr1.number_of_isolated_vertices() &&
     !arr2.number_of_isolated_vertices())
  {
     // clear the result arrangement
    res.clear();

    //perform the sweep whith overlay visitor
    Visitor    visitor(arr1, arr2, res, traits);
    Traits     meta_traits(res.get_traits());
    Sweep_line sweep_object(&meta_traits, &visitor);
    sweep_object.sweep(begin, end);
    return;

  }

  // iterate over arr1's vertices and associate each isolated point with
  // its vertex
  std::list<Point_2>                iso_points;

  Vertex_const_iterator_1 v_itr1;

  for(v_itr1 = arr1.vertices_begin();
      v_itr1 != arr1.vertices_end();
      ++v_itr1)
  {
    if(v_itr1->is_isolated())
    {
      iso_points.push_back(Point_2(v_itr1->point(),
                           CGAL::make_object(v_itr1),
                           Object()));
    }
  }
      
  // iterate over arr2's vertices and associate each isolated point with
  // its vertex
  Vertex_const_iterator_2 v_itr2;

  for (v_itr2 = arr2.vertices_begin();
       v_itr2 != arr2.vertices_end();
       ++v_itr2)
  {
    if (v_itr2->is_isolated())
    {
      iso_points.push_back(Point_2(v_itr2->point(),
                                   Object(),
                                   CGAL::make_object(v_itr2)));
    }
  }

  // clear the result arrangement
  res.clear();

  //perform the sweep whith overlay visitor
  Visitor    visitor(arr1, arr2, res, traits);
  Traits     meta_traits(res.get_traits());
  Sweep_line sweep_object(&meta_traits, &visitor);
  sweep_object.sweep(begin,
                     end,
                     iso_points.begin(),
                     iso_points.end());
}



CGAL_END_NAMESPACE

#endif