Merge pull request #1506 from lrineau/Mesh_3-fix_issue_1501-lrineau

Mesh_3: fix issue #1501 - about degenerate cases in initialization

Mesh_3/include/CGAL/Mesh_3/C3T3_helpers.h

@@ -775,6 +775,8 @@ public:
                                    ForwardIterator last_cell,
                                    Moving_vertices_set& moving_vertices);
 
+  void update_restricted_facets();
+
 #ifdef CGAL_INTRUSIVE_LIST
   template <typename OutdatedCells>
   void rebuild_restricted_delaunay(OutdatedCells& outdated_cells,
@@ -2863,6 +2865,17 @@ rebuild_restricted_delaunay(ForwardIterator first_cell,
   }
 }
 
+template <typename C3T3, typename MD>
+void
+C3T3_helpers<C3T3, MD>::
+update_restricted_facets()
+{
+  Update_c3t3 updater(domain_, c3t3_);
+  for (typename C3T3::Triangulation::Finite_facets_iterator
+    fit = tr_.finite_facets_begin();
+    fit != tr_.finite_facets_end(); ++fit)
+    updater(*fit);
+}
 
 template <typename C3T3, typename MD>
 template <typename OutdatedCellsOutputIterator,

Mesh_3/include/CGAL/make_mesh_3.h

@@ -31,6 +31,7 @@
 #include <CGAL/tags.h>
 #include <CGAL/Mesh_3/Protect_edges_sizing_field.h>
 #include <CGAL/Mesh_3/Has_features.h>
+#include <CGAL/Mesh_3/C3T3_helpers.h>
 
 #include <boost/mpl/has_xxx.hpp>
 
@@ -262,7 +263,17 @@ struct C3t3_initializer < C3T3, MD, MC, true, CGAL::Tag_true >
 
       // If c3t3 initialization is not sufficient (may happen if there is only
       // a planar curve as feature for example), add some surface points
-      if ( c3t3.triangulation().dimension() != 3 ) {
+
+      bool need_more_init = c3t3.triangulation().dimension() != 3;
+      if(!need_more_init) {
+        CGAL::Mesh_3::C3T3_helpers<C3T3, MD> helper(c3t3, domain);
+        helper.update_restricted_facets();
+
+        if (c3t3.number_of_facets() == 0) {
+          need_more_init = true;
+        }
+      }
+      if(need_more_init) {
         init_c3t3(c3t3, domain, criteria, nb_initial_points);
       }
     }

Polyhedron/demo/Polyhedron/Scene_c3t3_item.cpp

@@ -1387,10 +1387,6 @@ void Scene_c3t3_item_priv::computeElements()
     }
   }
 
-
-  if (item->isEmpty()){
-    return;
-  }
   //The facets
   {
     for (C3t3::Facet_iterator