VTK formats, distributed mesh and synchronizer

Closes #52 (closed) and #73 (closed).

src/TNL/Meshes/Writers/VTUWriter.h

+/***************************************************************************
+                          VTUWriter.h  -  description
+                             -------------------
+    begin                : Mar 18, 2020
+    copyright            : (C) 2020 by Tomas Oberhuber et al.
+    email                : tomas.oberhuber@fjfi.cvut.cz
+ ***************************************************************************/
+
+/* See Copyright Notice in tnl/Copyright */
+
+// Implemented by: Jakub Klinkovský
+
+#pragma once
+
+#include <TNL/Meshes/Grid.h>
+#include <TNL/Meshes/Mesh.h>
+#include <TNL/Meshes/VTKTraits.h>
+
+namespace TNL {
+namespace Meshes {
+namespace Writers {
+
+namespace details {
+
+template< typename Mesh, int EntityDimension > struct MeshEntitiesVTUCollector;
+
+} // namespace details
+
+template< typename Mesh >
+class VTUWriter
+{
+   static_assert( Mesh::getMeshDimension() <= 3, "The VTK format supports only 1D, 2D and 3D meshes." );
+   // TODO: check also world dimension when grids allow it
+//   static_assert( Mesh::getWorldDimension() <= 3, "The VTK format supports only 1D, 2D and 3D meshes." );
+
+   template< int EntityDimension >
+   using EntitiesCollector = details::MeshEntitiesVTUCollector< Mesh, EntityDimension >;
+
+   using HeaderType = std::uint64_t;
+public:
+   using MeshRealType = typename Mesh::RealType;
+   using IndexType = typename Mesh::GlobalIndexType;
+
+   VTUWriter() = delete;
+
+   VTUWriter( std::ostream& str, VTK::FileFormat format = VTK::FileFormat::ascii )
+   : str(str), format(format)
+   {}
+
+   template< int EntityDimension = Mesh::getMeshDimension() >
+   void writeEntities( const Mesh& mesh );
+
+   // If desired, cycle and time of the simulation can put into the file. This follows the instructions at
+   // http://www.visitusers.org/index.php?title=Time_and_Cycle_in_VTK_files
+   void writeMetadata( std::int32_t cycle = -1, double time = -1 );
+
+   template< typename Array >
+   void writeDataArray( const Array& array,
+                        const String& name,
+                        const int numberOfComponents = 1 );
+
+   ~VTUWriter();
+
+protected:
+   void writeHeader( const Mesh& mesh );
+
+   void writeFooter();
+
+   void writePoints( const Mesh& mesh );
+
+   std::ostream& str;
+
+   VTK::FileFormat format;
+
+   // number of points written to the file
+   IndexType pointsCount = 0;
+
+   // number of cells (in the VTK sense) written to the file
+   IndexType cellsCount = 0;
+
+   // indicator if the <VTKFile> tag is open
+   bool vtkfileOpen = false;
+
+   // indicator if a <Piece> tag is open
+   bool pieceOpen = false;
+
+   // number of data arrays written in each section
+   int cellDataArrays = 0;
+   int pointDataArrays = 0;
+
+   // indicator of the current section
+   VTK::DataType currentSection = VTK::DataType::CellData;
+};
+
+} // namespace Writers
+} // namespace Meshes
+} // namespace TNL
+
+#include <TNL/Meshes/Writers/VTUWriter.hpp>