Implementation of ParMesh::GenerateBoundaryElements()

mesh/mesh.hpp

@@ -970,6 +970,7 @@ class Mesh
    int AddBdrPoint(int v, int attr = 1);
 
    virtual void GenerateBoundaryElements();
+
    /// Finalize the construction of a triangular Mesh.
    void FinalizeTriMesh(int generate_edges = 0, int refine = 0,
                         bool fix_orientation = true);

mesh/pmesh.cpp

@@ -977,6 +977,9 @@ void ParMesh::Load(istream &input, int generate_edges, int refine,
       pncmesh->GetConformingSharedStructures(*this);
    }
 
+   // Assume FinalizeTopology() has been called in Loader
+   FinalizeParTopo();
+
    Finalize(refine, fix_orientation);
 
    EnsureParNodes();
@@ -3199,6 +3202,53 @@ int ParMesh::GetNFbyType(FaceType type) const
    return Mesh::GetNFbyType(type);
 }
 
+void ParMesh::GenerateBoundaryElements()
+{
+   for (auto &b : boundary)
+   {
+      FreeElement(b);
+   }
+
+   if (Dim == 3)
+   {
+      delete bel_to_edge;
+      bel_to_edge = NULL;
+   }
+
+   const Array<int> *s2l_face;
+   if (Dim == 1) { s2l_face = &svert_lvert; }
+   else if (Dim == 2) { s2l_face = &sedge_ledge; }
+   else { s2l_face = &sface_lface; }
+
+   // mark the shared local elements
+   Array<bool> l2s_marker(GetNumFaces());
+   l2s_marker = false;
+   for (int l : *s2l_face) { l2s_marker[l] = true; }
+
+   // count the 'NumOfBdrElements'
+   NumOfBdrElements = 0;
+   for (int i = 0; i < faces_info.Size(); i++)
+   {
+      const auto &fi = faces_info[i];
+      if (fi.Elem2No < 0 && !l2s_marker[i])
+      { ++NumOfBdrElements; }
+   }
+
+   // Add the boundary elements
+   boundary.SetSize(NumOfBdrElements);
+   be_to_face.SetSize(NumOfBdrElements);
+   for (int i = 0, j = 0; i < faces_info.Size(); i++)
+   {
+      if (faces_info[i].Elem2No < 0 && !l2s_marker[i])
+      {
+         boundary[j] = faces[i]->Duplicate(this);
+         be_to_face[j++] = i;
+      }
+   }
+
+   // Note: in 3D, 'bel_to_edge' is destroyed but it's not updated.
+}
+
 // shift cyclically 3 integers a, b, c, so that the smallest of
 // order[a], order[b], order[c] is first
 static inline

mesh/pmesh.hpp

@@ -646,8 +646,7 @@ class ParMesh : public Mesh
        shared faces) are counted excluding all master non-conforming faces. */
    int GetNFbyType(FaceType type) const override;
 
-   void GenerateBoundaryElements() override
-   { MFEM_ABORT("Generation of boundary elements works properly only on serial meshes."); }
+   void GenerateBoundaryElements() override;
 
    /// See the remarks for the serial version in mesh.hpp
    MFEM_DEPRECATED void ReorientTetMesh() override;