rw-anderson · rw-anderson · Nov 21, 2019 · Nov 21, 2019
diff --git a/mesh/mesh.cpp b/mesh/mesh.cpp
@@ -25,6 +25,7 @@
 #include <cstring>
 #include <ctime>
 #include <functional>
+#include <set>
 
 // Include the METIS header, if using version 5. If using METIS 4, the needed
 // declarations are inlined below, i.e. no header is needed.
@@ -6997,6 +6998,61 @@ bool Mesh::NonconformingDerefinement(Array<double> &elem_error,
    return true;
 }
 
+bool Mesh::GeneralDerefinement(Array<int>& derefs)
+{
+   MFEM_VERIFY(ncmesh, "Only supported for non-conforming meshes.");
+   MFEM_VERIFY(!NURBSext, "Derefinement of NURBS meshes is not supported. "
+               "Project the NURBS to Nodes first.");
+
+   DeleteLazyTables();
+
+   if (!derefs.Size()) { return false; }
+
+   const Table &dt = ncmesh->GetDerefinementTable();
+   Table dtT;
+   Transpose(dt, dtT);
+
+   // dt.Print();
+   // printf("dtT:\n");
+   // dtT.Print();
+
+   // Find the set of rows in the refinement table which correspond to
+   // the specified elements
+   std::set<int> set_rows;
+   for (int i = 0; i < derefs.Size(); i++) {
+      int el = derefs[i];
+      const int *row = dtT.GetRow(el);
+      set_rows.insert(row[0]);
+   }
+
+   Array<int> deref_rows;
+   std::set<int>::iterator it;
+   for (it = set_rows.begin(); it != set_rows.end(); ++it) {
+      deref_rows.Append(*it);
+   }
+
+   ncmesh->Derefine(deref_rows);
+
+   Mesh* mesh2 = new Mesh(*ncmesh);
+   ncmesh->OnMeshUpdated(mesh2);
+
+   Swap(*mesh2, false);
+   delete mesh2;
+
+   GenerateNCFaceInfo();
+
+   last_operation = Mesh::DEREFINE;
+   sequence++;
+
+   if (Nodes) // update/interpolate mesh curvature
+   {
+      Nodes->FESpace()->Update();
+      Nodes->Update();
+   }
+
+   return true;
+}
+
 bool Mesh::DerefineByError(Array<double> &elem_error, double threshold,
                            int nc_limit, int op)
 {

diff --git a/mesh/mesh.hpp b/mesh/mesh.hpp
@@ -1108,6 +1108,9 @@ class Mesh
    bool RefineByError(const Vector &elem_error, double threshold,
                       int nonconforming = -1, int nc_limit = 0);
 
+   /** Derefine specified elements (and associated children as required) */
+   bool GeneralDerefinement(Array<int> &el);
+
    /** Derefine the mesh based on an error measure associated with each
        element. A derefinement is performed if the sum of errors of its fine
        elements is smaller than 'threshold'. If 'nc_limit' > 0, derefinements

diff --git a/miniapps/derefine-experiment/main.cpp b/miniapps/derefine-experiment/main.cpp
@@ -0,0 +1,58 @@
+#include "mfem.hpp"
+
+#include <fstream>
+#include <iostream>
+
+using namespace std;
+using namespace mfem;
+
+const char *vishost = "localhost";
+const int visport = 19916;
+const int visw = 480;
+const int vish = 480;
+const int border = 15;
+socketstream vis;
+bool visualization = true;
+
+void vismesh(Mesh* mesh)
+{
+   if (visualization && vis.good())
+   {
+      vis.precision(8);
+      vis << "mesh" << endl << *mesh << flush;
+      vis << "window_title '" << "Mesh" << "'" << endl
+          << "window_geometry "
+          << (vish + border) << " " << 0
+          << " " << visw << " " << vish  << endl
+          << "keys mgA" << endl;
+   }
+}
+
+int main(int argc, char *argv[])
+{
+   vis.open(vishost, visport);
+
+   const char *mesh_file = "../../data/inline-quad.mesh";
+   // const char *mesh_file = "../../data/star.mesh";
+
+   Mesh *mesh = new Mesh(mesh_file, 1, 1);
+   mesh->EnsureNCMesh();
+
+   Array<Refinement> refs(2);
+   refs[0] = Refinement(0);
+   refs[1] = Refinement(5);
+   mesh->GeneralRefinement(refs, 1, 1);
+
+//   vismesh(mesh);
+
+   const Table &dt = mesh->ncmesh->GetDerefinementTable();
+   dt.Print();
+   Array<int> derefs(1);
+   derefs[0] = 3;
+
+   mesh->GeneralDerefinement(derefs);
+
+   vismesh(mesh);
+
+   return 0;
+}
diff --git a/miniapps/derefine-experiment/makefile b/miniapps/derefine-experiment/makefile
@@ -0,0 +1,62 @@
+# Copyright (c) 2010, Lawrence Livermore National Security, LLC. Produced at the
+# Lawrence Livermore National Laboratory. LLNL-CODE-443211. All Rights reserved.
+# See file COPYRIGHT for details.
+#
+# This file is part of the MFEM library. For more information and source code
+# availability see http://mfem.org.
+#
+# MFEM is free software; 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) version 2.1 dated February 1999.
+
+# Use the MFEM build directory
+MFEM_DIR ?= ../..
+MFEM_BUILD_DIR ?= ../..
+SRC = $(if $(MFEM_DIR:../..=),$(MFEM_DIR)/miniapps/derefine-experiment/,)
+CONFIG_MK = $(MFEM_BUILD_DIR)/config/config.mk
+# Use the MFEM install directory
+# MFEM_INSTALL_DIR = ../../mfem
+# CONFIG_MK = $(MFEM_INSTALL_DIR)/share/mfem/config.mk
+
+MFEM_LIB_FILE = mfem_is_not_built
+-include $(CONFIG_MK)
+
+# Some choices below are based on the OS type:
+NOTMAC := $(subst Darwin,,$(shell uname -s))
+ifneq ($(NOTMAC),)
+   SOPREFIX = so
+else
+   SOPREFIX = install_
+endif
+
+SEQ_MINIOBJS =
+PAR_MINIOBJS =
+ifeq ($(MFEM_USE_MPI),NO)
+   MINIOBJS = $(SEQ_MINIOBJS)
+else
+   MINIOBJS = $(PAR_MINIOBJS) $(SEQ_MINIOBJS)
+endif
+
+.SUFFIXES:
+.SUFFIXES: .o .cpp .mk
+.PHONY: all cln clean clean-build clean-exec
+
+# Remove built-in rule
+%.o: %.cpp
+
+# Replace the default implicit rule for *.cpp files
+%.o: $(SRC)%.cpp $(SRC)%.hpp $(CONFIG_MK)
+	$(MFEM_CXX) -c -fPIC $(MFEM_FLAGS) $< -o $@
+
+all: derefine-experiment
+
+derefine-experiment: main.cpp
+	$(MFEM_CXX) $(MFEM_FLAGS) main.cpp -o derefine-experiment $(MFEM_LIBS)
+
+# Generate an error message if the MFEM library is not built and exit
+$(MFEM_LIB_FILE):
+	$(error The MFEM library is not built)
+
+cln clean:
+	rm -f *.o *~
+	rm -rf *.dSYM *.TVD.*breakpoints $(SEQ_MINIOBJS) derefine-experiment