read_off(istream&, Surface_mesh) now appends

BGL/include/CGAL/boost/graph/io.h

@@ -0,0 +1,159 @@
+// Copyright (c) 2015  GeometryFactory (France).  All rights reserved.
+//
+// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public License as
+// published by the Free Software Foundation; either version 3 of the License,
+// or (at your option) any later version.
+//
+// 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)     : Andreas Fabri
+
+#ifndef CGAL_BOOST_GRAPH_IO_H
+#define CGAL_BOOST_GRAPH_IO_H
+
+#include <CGAL/boost/graph/Euler_operations.h>
+#include <CGAL/boost/graph/helpers.h>
+#include <iostream>
+#include <algorithm>
+#include <sstream>
+#include <string>
+#include <boost/foreach.hpp>
+#include <boost/container/flat_map.hpp>
+
+namespace CGAL {
+/*!
+   \ingroup PkgBGLHelperFct
+    writes the graph `g` in the OFF format.
+    \sa Overloads of this function for specific models of the concept `FaceGraph`.
+
+  */ 
+template <typename FaceGraph>
+void write_off(std::ostream& os,
+               const FaceGraph& g)
+{
+  typedef typename boost::graph_traits<FaceGraph>::vertex_descriptor vertex_descriptor;
+  typedef typename boost::graph_traits<FaceGraph>::face_descriptor face_descriptor;
+  typedef typename boost::graph_traits<FaceGraph>::vertices_size_type vertices_size_type;
+  typedef typename boost::graph_traits<FaceGraph>::faces_size_type faces_size_type;
+
+  typename boost::property_map<FaceGraph, CGAL::vertex_point_t>::type vpm = get(CGAL::vertex_point,g);
+  vertices_size_type nv = static_cast<vertices_size_type>(std::distance(vertices(g).first, vertices(g).second));
+  faces_size_type nf = static_cast<faces_size_type>(std::distance(faces(g).first, faces(g).second));
+
+  os << "OFF\n" << nv << " " << nf << " 0\n";
+  boost::container::flat_map<vertex_descriptor,vertices_size_type> reindex;
+  int n = 0;
+  BOOST_FOREACH(vertex_descriptor v, vertices(g)){
+    os << get(vpm,v) << '\n';
+    reindex[v]=n++;
+  }
+  
+  BOOST_FOREACH(face_descriptor f, faces(g)){
+    os << degree(f,g);
+    BOOST_FOREACH(vertex_descriptor v, vertices_around_face(halfedge(f,g),g)){
+      os << " " << reindex[v];
+    }
+    os << '\n';
+  }
+}
+
+  namespace internal { namespace read_off {
+  
+  bool is_whitespace(const std::string& s)
+  {
+    for(int i=0; i < s.size(); i++){
+      if(s[i] != ' ' && s[i] != '\t'){
+        return false;
+      }
+    }
+    return true;
+  }
+  
+std::string next_non_comment(std::istream& is)
+{
+  std::string line;
+  do {
+    std::getline(is, line);
+  }while(line[0] == '#' || is_whitespace(line));
+  return line;
+}
+
+    }
+  } // namespace internal
+
+
+/*!
+   \ingroup PkgBGLIOFct
+    reads the graph `g` from data in the OFF format. Ignores comment lines which start with a hash, and lines with whitespace.
+    \sa Overloads of this function for specific models of the concept `FaceGraph`.
+    \pre The data must represent a 2-manifold
+
+  */ 
+template <typename FaceGraph>
+bool read_off(std::istream& is,
+              FaceGraph& g)
+{
+  using namespace internal::read_off;
+
+  typedef typename boost::graph_traits<FaceGraph>::vertex_descriptor vertex_descriptor;
+  typedef typename boost::graph_traits<FaceGraph>::face_descriptor face_descriptor;
+  typedef typename boost::graph_traits<FaceGraph>::vertices_size_type vertices_size_type;
+  typedef typename boost::graph_traits<FaceGraph>::faces_size_type faces_size_type;
+
+  typedef typename boost::property_map<FaceGraph, CGAL::vertex_point_t>::type Vpm;
+  typedef  typename boost::property_traits<Vpm>::value_type Point_3;
+  Vpm vpm = get(CGAL::vertex_point,g);
+  vertices_size_type nv, nvf;
+  faces_size_type nf;
+  int ignore;
+  
+  std::string line = next_non_comment(is);
+  {
+    std::istringstream iss(line);
+    std::string off;
+    iss >> off;
+    CGAL_assertion( off == "OFF");
+  }
+  line = next_non_comment(is);
+  {
+    std::istringstream iss(line);
+    iss >> nv >> nf >> ignore;
+  }
+  
+  std::vector<vertex_descriptor> vertices(nv);
+  Point_3 p;
+  for(vertices_size_type i=0; i < nv; i++){
+    line = next_non_comment(is);
+    std::istringstream iss(line);
+    iss >> p;
+    vertices[i] = add_vertex(g);
+    put(vpm,vertices[i],p);
+  }
+
+  for(faces_size_type i=0; i < nf; i++){
+    line = next_non_comment(is);
+    std::istringstream iss(line);
+    iss >> nvf;
+    std::vector<faces_size_type> face(nvf);
+    for(vertices_size_type j = 0; j < nvf; j++){
+      faces_size_type fvi;
+      iss >> fvi;
+      face[j] = vertices[fvi];
+    }
+    Euler::add_face(face,g);
+  }
+  return true;
+}
+
+} // namespace CGAL
+
+#endif // CGAL_BOOST_GRAPH_IO_H

Surface_mesh/include/CGAL/Surface_mesh/Surface_mesh.h

@@ -45,6 +45,7 @@
 #include <CGAL/Surface_mesh/IO.h>
 #include <CGAL/Surface_mesh/Properties.h>
 #include <CGAL/boost/graph/graph_traits_Surface_mesh.h>
+#include <CGAL/boost/graph/copy_face_graph.h>
 #include <CGAL/boost/graph/iterator.h>
 #include <CGAL/boost/graph/Euler_operations.h>
 #include <CGAL/IO/File_scanner_OFF.h>
@@ -2015,17 +2016,11 @@ private: //------------------------------------------------------- private data
       in.putback(c);
       return in;
   }
-/// @endcond
 
 
 
-  /// \relates Surface_mesh
-  /// Extracts the surface mesh from an input stream in Ascii OFF, COFF, NOFF, CNOFF format.
-  /// The operator reads the point property as well as "v:normal", "v:color", and "f:color".
-  /// Vertex texture coordinates are ignored.
-  /// \pre `operator>>(std::istream&,const P&)` must be defined.
   template <typename P>
-  bool read_off(std::istream& is, Surface_mesh<P>& sm)
+  bool read_off_clear(std::istream& is, Surface_mesh<P>& sm)
   {
    typedef Surface_mesh<P> Mesh;
    typedef typename Kernel_traits<P>::Kernel K;
@@ -2126,6 +2121,27 @@ private: //------------------------------------------------------- private data
     }
     return is.good();
   }
+/// @endcond
+
+  /// \relates Surface_mesh
+  /// Extracts the surface mesh from an input stream in Ascii OFF, COFF, NOFF, CNOFF format.
+  /// The operator reads the point property as well as "v:normal", "v:color", and "f:color".
+  /// Vertex texture coordinates are ignored.
+  /// \pre `operator>>(std::istream&,const P&)` must be defined.
+
+  template <typename P>
+  bool read_off(std::istream& is, Surface_mesh<P>& sm)
+  {
+    if( (sm.num_vertices() == 0) && (sm.num_halfedges() == 0)&& (sm.num_faces() == 0) ){
+      return read_off_clear(is,sm);
+    }
+    Surface_mesh<P> other;
+    if(read_off_clear(is,other)){
+      copy_face_graph(other,sm);
+      return true;
+    }
+    return false;
+  }
 
  
   /// \relates Surface_mesh