add methods to importer to create a mesh based on halfedges

src/OpenMesh/Core/IO/importer/BaseImporter.hh

@@ -99,10 +99,16 @@ public:
   // add a vertex without coordinate. Use set_point to set the position deferred
   virtual VertexHandle add_vertex() = 0;
 
+  // add an edge. Use set_next, set_vertex and set_face to set corresponding entities for halfedges
+  virtual HalfedgeHandle add_edge(VertexHandle _vh0, VertexHandle _vh1) = 0;
+
   // add a face with indices _indices refering to vertices
   typedef std::vector<VertexHandle> VHandles;
   virtual FaceHandle add_face(const VHandles& _indices) = 0;
 
+  // add a face with incident halfedge
+  virtual FaceHandle add_face(HalfedgeHandle _heh) = 0;
+
   // add texture coordinates per face, _vh references the first texcoord
   virtual void add_face_texcoords( FaceHandle _fh, VertexHandle _vh, const std::vector<Vec2f>& _face_texcoords) = 0;
 
@@ -115,6 +121,9 @@ public:
   // Set coordinate of the given vertex. Use this function, if you created a vertex without coordinate
   virtual void set_point(VertexHandle _vh, const Vec3f& _point) = 0;
 
+  // Set outgoing halfedge for the given vertex.
+  virtual void set_halfedge(VertexHandle _vh, HalfedgeHandle _heh) = 0;
+
   // set vertex normal
   virtual void set_normal(VertexHandle _vh, const Vec3f& _normal) = 0;
 
@@ -133,6 +142,12 @@ public:
   // set vertex texture coordinate
   virtual void set_texcoord(VertexHandle _vh, const Vec2f& _texcoord) = 0;
 
+  // set next halfedge handle
+  virtual void set_next(HalfedgeHandle _heh, HalfedgeHandle _next) = 0;
+
+  // set incident face handle for given halfedge
+  virtual void set_face(HalfedgeHandle _heh, FaceHandle _fh) = 0;
+
   // set vertex texture coordinate
   virtual void set_texcoord(HalfedgeHandle _heh, const Vec2f& _texcoord) = 0;
 

src/OpenMesh/Core/IO/importer/ImporterT.hh

@@ -107,6 +107,11 @@ public:
     return mesh_.new_vertex();
   }
 
+  virtual HalfedgeHandle add_edge(VertexHandle _vh0, VertexHandle _vh1) override
+  {
+    return mesh_.new_edge(_vh0, _vh1);
+  }
+
   virtual FaceHandle add_face(const VHandles& _indices)
   {
     FaceHandle fh;
@@ -192,6 +197,13 @@ public:
     return fh;
   }
 
+  virtual FaceHandle add_face(HalfedgeHandle _heh) override
+  {
+    auto fh = mesh_.new_face();
+    mesh_.set_halfedge_handle(fh, _heh);
+    return fh;
+  }
+
   // vertex attributes
 
   virtual void set_point(VertexHandle _vh, const Vec3f& _point)
@@ -199,6 +211,11 @@ public:
     mesh_.set_point(_vh,vector_cast<Point>(_point));
   }
 
+  virtual void set_halfedge(VertexHandle _vh, HalfedgeHandle _heh) override
+  {
+    mesh_.set_halfedge_handle(_vh, _heh);
+  }
+
   virtual void set_normal(VertexHandle _vh, const Vec3f& _normal)
   {
     if (mesh_.has_vertex_normals())
@@ -240,6 +257,17 @@ public:
       mesh_.set_texcoord2D(_vh, vector_cast<TexCoord2D>(_texcoord));
   }
 
+  virtual void set_next(HalfedgeHandle _heh, HalfedgeHandle _next) override
+  {
+    mesh_.set_next_halfedge_handle(_heh, _next);
+  }
+
+  virtual void set_face(HalfedgeHandle _heh, FaceHandle _fh) override
+  {
+    mesh_.set_face_handle(_heh, _fh);
+  }
+
+
   virtual void set_texcoord(HalfedgeHandle _heh, const Vec2f& _texcoord)
   {
     if (mesh_.has_halfedge_texcoords2D())