add methods to exporter for accessing halfedges for vertices and faces and for...

add methods to exporter for accessing halfedges for vertices and faces and for accessing next halfface, incident vertex and incident face for halfedges

src/OpenMesh/Core/IO/exporter/BaseExporter.hh

@@ -110,6 +110,14 @@ public:
   virtual unsigned int
   get_vhandles(FaceHandle _fh,
 	       std::vector<VertexHandle>& _vhandles) const=0;
+
+  // information needed for a halfedge based data structure such as OpenMesh
+  virtual int get_halfedge_id(VertexHandle _vh) = 0;
+  virtual int get_halfedge_id(FaceHandle _vh) = 0;
+  virtual int get_next_halfedge_id(HalfedgeHandle _heh) = 0;
+  virtual int get_to_vertex_id(HalfedgeHandle _heh) = 0;
+  virtual int get_face_id(HalfedgeHandle _heh) = 0;
+
   ///
   /// \brief getHeh returns the HalfEdgeHandle that belongs to the face
   ///  specified by _fh and has a toVertexHandle that corresponds to _vh.

src/OpenMesh/Core/IO/exporter/ExporterT.hh

@@ -230,6 +230,31 @@ public:
     return count;
   }
 
+  int get_halfedge_id(VertexHandle _vh) override
+  {
+    return mesh_.halfedge_handle(_vh).idx();
+  }
+
+  int get_halfedge_id(FaceHandle _fh) override
+  {
+    return mesh_.halfedge_handle(_fh).idx();
+  }
+
+  int get_next_halfedge_id(HalfedgeHandle _heh) override
+  {
+    return mesh_.next_halfedge_handle(_heh).idx();
+  }
+
+  int get_to_vertex_id(HalfedgeHandle _heh) override
+  {
+    return mesh_.to_vertex_handle(_heh).idx();
+  }
+
+  int get_face_id(HalfedgeHandle _heh) override
+  {
+    return mesh_.face_handle(_heh).idx();
+  }
+
   unsigned int get_face_texcoords(std::vector<Vec2f>& _hehandles) const
   {
     unsigned int count(0);