From f6cd69aa7b315b10302b6e042450e86aaaf9e870 Mon Sep 17 00:00:00 2001
From: Guillaume Damiand <guillaume.damiand@liris.cnrs.fr>
Date: Mon, 19 Dec 2011 06:38:04 +0000
Subject: [PATCH] Add an example to build voronoi_2.

---
 .gitattributes                                |   1 +
 .../Linear_cell_complex/CMakeLists.txt        |   6 +
 .../Linear_cell_complex/voronoi_2.cpp         | 114 ++++++++++++++++++
 .../CGAL/Linear_cell_complex_constructors.h   | 101 ++++++++++++++++
 4 files changed, 222 insertions(+)
 create mode 100644 Linear_cell_complex/examples/Linear_cell_complex/voronoi_2.cpp

diff --git a/.gitattributes b/.gitattributes
index 89984985f1e..5dd79c5cd02 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -2036,6 +2036,7 @@ Linear_cell_complex/examples/Linear_cell_complex/linear_cell_complex_3_viewer_vt
 Linear_cell_complex/examples/Linear_cell_complex/linear_cell_complex_3_with_colored_vertices.cpp -text
 Linear_cell_complex/examples/Linear_cell_complex/linear_cell_complex_4.cpp -text
 Linear_cell_complex/examples/Linear_cell_complex/plane_graph_to_lcc_2.cpp -text
+Linear_cell_complex/examples/Linear_cell_complex/voronoi_2.cpp -text
 Linear_cell_complex/examples/Linear_cell_complex/voronoi_3.cpp -text
 Linear_cell_complex/include/CGAL/Cell_attribute_with_point.h -text
 Linear_cell_complex/include/CGAL/Linear_cell_complex.h -text
diff --git a/Linear_cell_complex/examples/Linear_cell_complex/CMakeLists.txt b/Linear_cell_complex/examples/Linear_cell_complex/CMakeLists.txt
index 03076670ce8..931b3b1ad54 100644
--- a/Linear_cell_complex/examples/Linear_cell_complex/CMakeLists.txt
+++ b/Linear_cell_complex/examples/Linear_cell_complex/CMakeLists.txt
@@ -45,6 +45,12 @@ if ( CGAL_FOUND )
   #include("CMakeLCCViewerQt.inc")
   #include("CMakeLCCViewerVtk.inc")
 
+  add_executable(voronoi_2 voronoi_2.cpp)
+  target_link_libraries(voronoi_2 ${CGAL_LIBRARIES} ${CGAL_3RD_PARTY_LIBRARIES})
+# And if you use a viewer, you have to link with the corresponding lib.
+  target_link_libraries(voronoi_2 ${MAP_VIEWER_LIBRARIES_QT})
+  #target_link_libraries(voronoi_3 ${MAP_VIEWER_LIBRARIES_VTK}) 
+
   add_executable(voronoi_3 voronoi_3.cpp)
   target_link_libraries(voronoi_3 ${CGAL_LIBRARIES} ${CGAL_3RD_PARTY_LIBRARIES})
 # And if you use a viewer, you have to link with the corresponding lib.
diff --git a/Linear_cell_complex/examples/Linear_cell_complex/voronoi_2.cpp b/Linear_cell_complex/examples/Linear_cell_complex/voronoi_2.cpp
new file mode 100644
index 00000000000..8e27bc00b3e
--- /dev/null
+++ b/Linear_cell_complex/examples/Linear_cell_complex/voronoi_2.cpp
@@ -0,0 +1,114 @@
+#include <CGAL/Linear_cell_complex.h>
+#include <CGAL/Linear_cell_complex_constructors.h>
+#include <CGAL/Linear_cell_complex_operations.h>
+#include <CGAL/Delaunay_triangulation_2.h>
+#include <iostream>
+#include <fstream>
+
+/* If you want to use a viewer, you can use one of the following file
+ * depending if you use vtk or qglviewer. */
+#ifdef CGAL_LCC_USE_QT
+//#include "linear_cell_complex_3_viewer_qt.h"
+#endif
+
+typedef CGAL::Linear_cell_complex<2> LCC_2;
+typedef LCC_2::Dart_handle           Dart_handle;
+typedef LCC_2::Point                 Point;
+
+typedef CGAL::Delaunay_triangulation_2<LCC_2::Traits> Triangulation;
+
+// Function used to display the voronoi diagram.
+void display_voronoi(LCC_2& alcc, Dart_handle adart)
+{
+  // We remove all the faces containing one dart of the infinite faces
+  std::stack<Dart_handle> toremove;
+  int mark_toremove=alcc.get_new_mark();
+
+  // We cannot view the infinite face since it does not have
+  // a correct geometry. For that we have to remove the infinite face.
+  toremove.push(adart);
+  CGAL::mark_cell<LCC_2,2>(alcc, adart, mark_toremove);
+ 
+  // Plus all the faces sharing an edge with it.
+  for (LCC_2::Dart_of_cell_range<2>::iterator
+         it=alcc.darts_of_cell<2>(adart).begin(),
+         itend=alcc.darts_of_cell<2>(adart).end(); it!=itend; ++it)
+  {
+    if ( !alcc.is_marked(it->beta(2), mark_toremove) )
+    {
+      CGAL::mark_cell<LCC_2,2>(alcc, it->beta(2), mark_toremove);
+      toremove.push(it->beta(2));
+    }    
+  }
+  
+  while( !toremove.empty() )
+  {
+    CGAL::remove_cell<LCC_2, 2>(alcc, toremove.top());
+    toremove.pop();
+  }
+
+#ifdef CGAL_LCC_USE_VIEWER
+  //  display_lcc(alcc);
+#endif // CGAL_LCC_USE_VIEWER
+}
+
+int main(int narg, char** argv)
+{
+  if (narg>1 && (!strcmp(argv[1],"-h") || !strcmp(argv[1],"-?")) )
+  {
+    std::cout<<"Usage : voronoi_2 filename"<<std::endl   
+             <<"   filename being a fine containing 3D points used to "
+             <<" compute the Delaunay_triangulation_3."<<std::endl;
+    return EXIT_FAILURE;
+  }
+
+  std::string filename;
+  if ( narg==1 )
+  {
+    filename=std::string("data/points");
+    std::cout<<"No filename given: use data/points by default."<<std::endl;
+  }
+  else
+    filename=std::string(argv[1]);
+  
+  // 1) Compute the Delaunay_triangulation_2.
+  Triangulation T;
+
+  std::ifstream iFile(filename.c_str());
+  if (!iFile)
+  {
+    std::cout << "Problem reading file " << filename << std::endl;
+    return EXIT_FAILURE;
+  }
+  
+  std::istream_iterator<Point> begin(iFile), end;
+  T.insert(begin, end);
+  assert(T.is_valid(false));
+ 
+  // 2) Convert the triangulation into a 2D lcc.
+  LCC_2 lcc;
+  Dart_handle dh=
+    CGAL::import_from_triangulation_2<LCC_2, Triangulation>(lcc, T);
+
+  std::cout<<"Delaunay triangulation :"<<std::endl<<"  ";
+  lcc.display_characteristics(std::cout) << ", valid=" 
+                                         << lcc.is_valid() << std::endl;
+
+  // 3) Compute the dual lcc.
+  LCC_2 dual_lcc;
+  Dart_handle ddh=CGAL::dual<LCC_2>(lcc, dual_lcc, dh);
+  // Here, dual_lcc is the 3D Voronoi diagram.
+  
+  // 4) Display the dual_lcc characteristics.
+  std::cout<<"Voronoi subdvision :"<<std::endl<<"  ";
+  dual_lcc.display_characteristics(std::cout) << ", valid=" 
+                                              << dual_lcc.is_valid()
+                                              << std::endl;
+
+#ifdef CGAL_LCC_USE_VIEWER
+  display_voronoi(dual_lcc, ddh);
+#endif // CGAL_LCC_USE_VIEWER
+
+  return EXIT_SUCCESS;
+}
+
diff --git a/Linear_cell_complex/include/CGAL/Linear_cell_complex_constructors.h b/Linear_cell_complex/include/CGAL/Linear_cell_complex_constructors.h
index ca008ec9b10..3425253468c 100644
--- a/Linear_cell_complex/include/CGAL/Linear_cell_complex_constructors.h
+++ b/Linear_cell_complex/include/CGAL/Linear_cell_complex_constructors.h
@@ -165,6 +165,107 @@ namespace CGAL {
     return first;
   }
 
+  /** Convert a given Triangulation_2 into a 2D linear cell complex.
+   * @param alcc the used linear cell complex.
+   * @param atr the Triangulation_2.
+   * @return A dart incident to the infinite vertex.
+   */
+  template < class LCC, class Triangulation >
+  typename LCC::Dart_handle import_from_triangulation_2
+  (LCC& alcc, const Triangulation &atr)
+  {
+    CGAL_static_assertion( LCC::dimension>=2 && LCC::ambient_dimension==2 );
+    
+    // Case of empty triangulations.
+    if (atr.number_of_vertices() == 0) return NULL;
+
+    // Check the dimension.
+    if (atr.dimension() != 2) return NULL;
+    CGAL_assertion(atr.is_valid());
+
+    typedef typename Triangulation::Vertex_handle    TVertex_handle;
+    typedef typename Triangulation::Vertex_iterator  TVertex_iterator;
+    typedef typename Triangulation::All_faces_iterator TFace_iterator;
+    typedef typename std::map
+      < TFace_iterator, typename LCC::Dart_handle >::iterator itmap_tcell;
+
+    // Create vertices in the map and associate in a map
+    // TVertex_handle and vertices in the map.
+    std::map< TVertex_handle, typename LCC::Vertex_attribute_handle > TV;
+    for (TVertex_iterator itv = atr.vertices_begin();
+         itv != atr.vertices_end(); ++itv)
+    {
+      //  if (it != atr.infinite_vertex())
+      {
+        TV[itv] = alcc.create_vertex_attribute(itv->point());
+      }
+    }
+
+    // Create the triangles and create a map to link Cell_iterator
+    // and triangles.
+    TFace_iterator it;
+
+    std::map< TFace_iterator, typename LCC::Dart_handle > TC;
+    itmap_tcell maptcell_it;
+
+    typename LCC::Dart_handle res=NULL, dart=NULL;
+    typename LCC::Dart_handle cur=NULL, neighbor=NULL;
+
+    for (it = atr.all_faces_begin(); it != atr.all_faces_end(); ++it)
+    {
+      /*     if (it->vertex(0) != atr.infinite_vertex() &&
+             it->vertex(1) != atr.infinite_vertex() &&
+             it->vertex(2) != atr.infinite_vertex() &&
+             it->vertex(3) != atr.infinite_vertex())
+      */
+      {
+        res = alcc.make_triangle(TV[it->vertex(0)],
+                                 TV[it->vertex(1)],
+                                 TV[it->vertex(2)]);
+
+        if ( it->vertex(0) == atr.infinite_vertex() && dart==NULL )
+          dart = res;
+
+        for (unsigned int i=0; i<3; ++i)
+        {
+          switch (i)
+          {
+          case 0: cur = res->beta(1); break;
+          case 1: cur = res->beta(0); break;
+          case 2: cur = res; break;
+          }
+
+          maptcell_it = TC.find(it->neighbor(i));
+          if (maptcell_it != TC.end())
+          {
+            switch (it->neighbor(i)->index(it))
+            {
+            case 0: neighbor =
+                maptcell_it->second->beta(1);
+              break;
+            case 1: neighbor =
+                maptcell_it->second->beta(0);
+              break;
+            case 2: neighbor = maptcell_it->second; break;
+            }
+            while (LCC::vertex_attribute(neighbor) !=
+                   LCC::vertex_attribute(cur->other_extremity()) )
+              neighbor = neighbor->beta(1);
+            alcc.template topo_sew<2>(cur, neighbor);
+            if (!neighbor->beta(0)->is_free(2) &&
+                !neighbor->beta(1)->is_free(2))
+              TC.erase(maptcell_it);
+          }
+        }
+        if (res->is_free(2) ||
+            res->beta(0)->is_free(3) ||
+            res->beta(1)->is_free(3))
+          TC[it] = res;
+      }
+    }
+    return dart;
+  }
+  
   /** Convert a given Triangulation_3 into a 3D linear cell complex.
    * @param alcc the used linear cell complex.
    * @param atr the Triangulation_3.