<h3>Specific improvements</h3>
<ol>
+ <li> New: GridGenerator::create_triangulation_with_removed_cells() creates
+ a new mesh out of an existing one by dropping individual cells.
+ <br>
+ (Wolfgang Bangerth, 2015/03/13)
+ </li>
+
<li> New: Add MueLu preconditioner from Trilinos. This is a new algebraic
multigrid package. The input parameters are almost the same as the ones
from ML so that the two preconditioners can be easily swapped.
const Triangulation<dim, spacedim> &triangulation_2,
Triangulation<dim, spacedim> &result);
+ /**
+ * This function creates a triangulation that consists of the same cells
+ * as are present in the first argument, except those cells that are listed
+ * in the second argument. The purpose of the function is to generate
+ * geometries <i>subtractively</i> from the geometry described by an
+ * existing triangulation. A prototypical case is a 2d domain with
+ * rectangular holes. This can be achieved by first meshing the entire
+ * domain and then using this function to get rid of the cells that
+ * are located at the holes. Likewise, you could create the mesh
+ * that GridGenerator::hyper_L() produces by starting with a
+ * GridGenerator::hyper_cube(), refining it once, and then calling
+ * the current function with a single cell in the second argument.
+ *
+ * @param[in] input_triangulation The original triangulation that serves as
+ * the template from which the new one is to be created.
+ * @param[in] cells_to_remove A list of cells of the triangulation provided
+ * as first argument that should be removed (i.e., that should not
+ * show up in the result.
+ * @param[out] result The resulting triangulation that consists of the same
+ * cells as are in @p input_triangulation, with the exception of the cells
+ * listed in @p cells_to_remove.
+ *
+ * @pre Because we cannot create triangulations de novo that contain
+ * adaptively refined cells, the input triangulation needs to have all
+ * of its cells on the same level. Oftentimes, this will in fact be
+ * the coarsest level, but it is allowed to pass in a triangulation
+ * that has been refined <i>globally</i> a number of times. The output
+ * triangulation will in that case simply be a mesh with only one
+ * level that consists of the active cells of the input minus the
+ * ones listed in the second argument. However, the input triangulation
+ * must not have been <i>adaptively</i> refined.
+ */
+ template <int dim, int spacedim>
+ void
+ create_triangulation_with_removed_cells (const Triangulation<dim, spacedim> &input_triangulation,
+ const std::set<typename Triangulation<dim, spacedim>::active_cell_iterator> &cells_to_remove,
+ Triangulation<dim, spacedim> &result);
+
/**
* Take a 2d Triangulation that is being extruded in z direction by the
+ template <int dim, int spacedim>
+ void
+ create_triangulation_with_removed_cells (const Triangulation<dim, spacedim> &input_triangulation,
+ const std::set<typename Triangulation<dim, spacedim>::active_cell_iterator> &cells_to_remove,
+ Triangulation<dim, spacedim> &result)
+ {
+ // simply copy the vertices; we will later strip those
+ // that turn out to be unused
+ std::vector<Point<spacedim> > vertices = input_triangulation.get_vertices();
+
+ // the loop through the cells and copy stuff, excluding
+ // the ones we are to remove
+ std::vector<CellData<dim> > cells;
+ for (typename Triangulation<dim,spacedim>::active_cell_iterator
+ cell = input_triangulation.begin_active(); cell != input_triangulation.end(); ++cell)
+ if (cells_to_remove.find(cell) == cells_to_remove.end())
+ {
+ Assert (static_cast<unsigned int>(cell->level()) == input_triangulation.n_levels()-1,
+ ExcMessage ("Your input triangulation appears to have "
+ "adaptively refined cells. This is not allowed. You can "
+ "only call this function on a triangulation in which "
+ "all cells are on the same refinement level."));
+
+ CellData<dim> this_cell;
+ for (unsigned int v=0; v<GeometryInfo<dim>::vertices_per_cell; ++v)
+ this_cell.vertices[v] = cell->vertex_index(v);
+ this_cell.material_id = cell->material_id();
+ cells.push_back (this_cell);
+ }
+
+ // throw out duplicated vertices from the two meshes, reorder vertices as
+ // necessary and create the triangulation
+ SubCellData subcell_data;
+ std::vector<unsigned int> considered_vertices;
+ GridTools::delete_duplicated_vertices (vertices, cells,
+ subcell_data,
+ considered_vertices);
+
+ // then clear the old triangulation and create the new one
+ result.clear ();
+ result.create_triangulation (vertices, cells, subcell_data);
+ }
+
+
+
void
extrude_triangulation(const Triangulation<2, 2> &input,
const unsigned int n_slices,
(const Triangulation<deal_II_dimension, deal_II_space_dimension> &triangulation_1,
const Triangulation<deal_II_dimension, deal_II_space_dimension> &triangulation_2,
Triangulation<deal_II_dimension, deal_II_space_dimension> &result);
+
+ template
+ void
+ create_triangulation_with_removed_cells (const Triangulation<deal_II_dimension, deal_II_space_dimension> &input_triangulation,
+ const std::set<typename Triangulation<deal_II_dimension, deal_II_space_dimension>::active_cell_iterator> &cells_to_remove,
+ Triangulation<deal_II_dimension, deal_II_space_dimension> &result);
#endif
\}
--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2005 - 2015 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, 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 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE at
+// the top level of the deal.II distribution.
+//
+// ---------------------------------------------------------------------
+
+
+
+// Test GridGenerator::create_triangulation_with_removed_cells
+
+#include "../tests.h"
+#include <deal.II/base/logstream.h>
+#include <deal.II/base/tensor.h>
+#include <deal.II/grid/tria.h>
+#include <deal.II/grid/grid_generator.h>
+#include <deal.II/grid/grid_out.h>
+#include <deal.II/fe/fe_q.h>
+
+#include <fstream>
+#include <iomanip>
+
+
+template<int dim>
+void test(std::ostream &out)
+{
+ Triangulation<dim> triangulation;
+ Triangulation<dim> tr;
+ GridGenerator::hyper_cube (triangulation);
+ triangulation.refine_global (3);
+
+ // remove all cells but the first. this is the hardest case to handle as it
+ // makes a bunch of vertices unused
+ std::set<typename Triangulation<dim>::active_cell_iterator>
+ cells_to_remove;
+ for (typename Triangulation<dim>::active_cell_iterator
+ cell = ++triangulation.begin_active();
+ cell != triangulation.end(); ++cell)
+ cells_to_remove.insert (cell);
+
+ GridGenerator::create_triangulation_with_removed_cells(triangulation,
+ cells_to_remove, tr);
+ GridOut go;
+ go.write_gnuplot(tr, out);
+}
+
+
+int main()
+{
+ std::ofstream logfile("output");
+ deallog.attach(logfile);
+ deallog.depth_console(0);
+ deallog.threshold_double(1.e-10);
+
+ test<2>(logfile);
+ test<3>(logfile);
+}
--- /dev/null
+
+0.00000 0.00000 0 0
+0.125000 0.00000 0 0
+0.125000 0.125000 0 0
+0.00000 0.125000 0 0
+0.00000 0.00000 0 0
+
+
+0.00000 0.00000 0.00000 0 0
+0.125000 0.00000 0.00000 0 0
+0.125000 0.00000 0.125000 0 0
+0.00000 0.00000 0.125000 0 0
+0.00000 0.00000 0.00000 0 0
+
+0.00000 0.125000 0.00000 0 0
+0.125000 0.125000 0.00000 0 0
+0.125000 0.125000 0.125000 0 0
+0.00000 0.125000 0.125000 0 0
+0.00000 0.125000 0.00000 0 0
+
+0.00000 0.00000 0.00000 0 0
+0.00000 0.125000 0.00000 0 0
+
+0.125000 0.00000 0.00000 0 0
+0.125000 0.125000 0.00000 0 0
+
+0.125000 0.00000 0.125000 0 0
+0.125000 0.125000 0.125000 0 0
+
+0.00000 0.00000 0.125000 0 0
+0.00000 0.125000 0.125000 0 0
+
projects / dealii.git / commitdiff