Add new example demonstrating grid views

src/04-gridviews.cc

+// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+// vi: set et ts=4 sw=2 sts=2:
+
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+
+
+// included standard library headers
+#include <iostream>
+#include <array>
+
+// included dune-common headers
+#include <dune/common/parallel/mpihelper.hh>
+#include <dune/common/exceptions.hh>
+#include <dune/common/fvector.hh>
+#include <dune/common/stringutility.hh>
+
+// included dune-geometry headers
+#include <dune/geometry/quadraturerules.hh>
+
+// included dune-grid headers
+#include <dune/grid/io/file/vtk/vtkwriter.hh>
+#include <dune/grid/utility/structuredgridfactory.hh>
+#include <dune/grid/yaspgrid.hh>
+#include <dune/grid/uggrid.hh>
+
+// included dune-fu-tutorial headers
+
+
+template<class Grid>
+auto createCubeGrid()
+{
+  static const int dim = Grid::dimension;
+
+  auto lowerLeft = Dune::FieldVector<double,dim>(0);
+  auto upperRight = Dune::FieldVector<double,dim>(1);
+  auto elementsPerDirection = std::array<unsigned int,dim>();
+  for(auto& e : elementsPerDirection)
+    e = 2;
+
+  return Dune::StructuredGridFactory<Grid>::createCubeGrid(lowerLeft, upperRight, elementsPerDirection);
+}
+
+template<class Grid>
+auto createSimplexGrid()
+{
+  static const int dim = Grid::dimension;
+
+  auto lowerLeft = Dune::FieldVector<double,dim>(0);
+  auto upperRight = Dune::FieldVector<double,dim>(1);
+  auto elementsPerDirection = std::array<unsigned int,dim>();
+  for(auto& e : elementsPerDirection)
+    e = 2;
+
+  return Dune::StructuredGridFactory<Grid>::createSimplexGrid(lowerLeft, upperRight, elementsPerDirection);
+}
+
+
+template<class GridView>
+void writeGridView(const GridView& gridView, std::string postFix)
+{
+  Dune::VTKWriter<GridView> vtkWriter(gridView);
+  vtkWriter.write(std::string("04-gridviews-")+postFix);
+}
+
+template<class Grid>
+void writeAllGridViews(const Grid& grid, std::string gridName)
+{
+  for(int level = 0; level <= grid.maxLevel(); ++level)
+    writeGridView(grid.levelGridView(level), Dune::formatString(gridName+"-level-%02d", level));
+  
+  writeGridView(grid.leafGridView(), gridName+"-leaf");
+}
+
+
+
+
+
+int main(int argc, char** argv)
+{
+  try{
+    // Maybe initialize MPI
+    Dune::MPIHelper& helper = Dune::MPIHelper::instance(argc, argv);
+
+    // Print process rank
+    if(Dune::MPIHelper::isFake)
+      std::cout<< "This is a sequential program." << std::endl;
+    else
+      std::cout<<"I am rank "<<helper.rank()<<" of "<<helper.size()
+        <<" processes!"<<std::endl;
+
+    {
+      using Grid = Dune::YaspGrid<2>;
+      auto gridPointer = createCubeGrid<Grid>();
+      Grid& grid = *gridPointer;
+      grid.globalRefine(2);
+      writeAllGridViews(grid, "2d_yaspgrid");
+    }
+
+    {
+      using Grid = Dune::YaspGrid<3>;
+      auto gridPointer = createCubeGrid<Grid>();
+      Grid& grid = *gridPointer;
+      grid.globalRefine(2);
+      writeAllGridViews(grid, "3d_yaspgrid");
+    }
+
+    {
+      using Grid = Dune::UGGrid<2>;
+      auto gridPointer = createSimplexGrid<Grid>();
+      Grid& grid = *gridPointer;
+      grid.globalRefine(2);
+      
+      for(int i=0; i<2; ++i)
+      {
+        auto gridView = grid.levelGridView(grid.maxLevel());
+        auto it = Dune::elements(gridView).begin();
+        grid.mark(1, *it);
+        grid.adapt();
+      }
+
+      writeAllGridViews(grid, "2d_uggrid");
+    }
+
+    return 0;
+  }
+  catch (Dune::Exception &e){
+    std::cerr << "Dune reported error: " << e << std::endl;
+  }
+  catch (...){
+    std::cerr << "Unknown exception thrown!" << std::endl;
+  }
+}

src/CMakeLists.txt

@@ -9,3 +9,6 @@ target_link_dune_default_libraries("02-basic-grid-interface")
 
 add_executable("03-function-integration" 03-function-integration.cc)
 target_link_dune_default_libraries("03-function-integration")
+
+add_executable("04-gridviews" 04-gridviews.cc)
+target_link_dune_default_libraries("04-gridviews")