# WriteVTU

VTKExamples/Cxx/IO/WriteVTU

### Description

This example writes a VTU file.

Other Languages

See (CSharp)

### Code

WriteVTU.cxx

    #include <vtkSmartPointer.h>
    #include <vtkTetra.h>
    #include <vtkCellArray.h>
    #include <vtkXMLUnstructuredGridReader.h>
    #include <vtkDataSetMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkXMLUnstructuredGridWriter.h>
    #include <vtkUnstructuredGrid.h>
    #include <vtkPointData.h>
    #include <vtkVertexGlyphFilter.h>

    int main(int argc, char *argv[])
    {
      // Parse command line arguments
      if(argc != 2)
      {
        std::cout << "Required arguments: OutputFilename" << std::endl;
        return EXIT_FAILURE;
      }

      std::string filename = argv[1];

      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(0, 0, 0);
      points->InsertNextPoint(1, 0, 0);
      points->InsertNextPoint(1, 1, 0);
      points->InsertNextPoint(0, 1, 1);

       vtkSmartPointer<vtkTetra> tetra =
        vtkSmartPointer<vtkTetra>::New();

      tetra->GetPointIds()->SetId(0, 0);
      tetra->GetPointIds()->SetId(1, 1);
      tetra->GetPointIds()->SetId(2, 2);
      tetra->GetPointIds()->SetId(3, 3);

      vtkSmartPointer<vtkCellArray> cellArray =
        vtkSmartPointer<vtkCellArray>::New();
      cellArray->InsertNextCell(tetra);

      vtkSmartPointer<vtkUnstructuredGrid> unstructuredGrid =
        vtkSmartPointer<vtkUnstructuredGrid>::New();
      unstructuredGrid->SetPoints(points);
      unstructuredGrid->SetCells(VTK_TETRA, cellArray);

      // Write file
      vtkSmartPointer<vtkXMLUnstructuredGridWriter> writer =
        vtkSmartPointer<vtkXMLUnstructuredGridWriter>::New();
      writer->SetFileName(filename.c_str());
      writer->SetInputData(unstructuredGrid);
      writer->Write();

      // Read and display file for verification that it was written correclty
      vtkSmartPointer<vtkXMLUnstructuredGridReader> reader =
        vtkSmartPointer<vtkXMLUnstructuredGridReader>::New();
      reader->SetFileName(filename.c_str());
      reader->Update();

      vtkSmartPointer<vtkDataSetMapper> mapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapper->SetInputConnection(reader->GetOutputPort());

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);

      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      renderer->AddActor(actor);
      renderer->SetBackground(.3, .6, .3); // Background color green

      renderWindow->Render();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(WriteVTU)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersGeneral
      vtkIOXML
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping WriteVTU: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(WriteVTU MACOSX_BUNDLE WriteVTU.cxx )
      target_link_libraries(WriteVTU PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(WriteVTU MACOSX_BUNDLE WriteVTU.cxx )
      target_link_libraries(WriteVTU PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS WriteVTU
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build WriteVTU

Click here to download WriteVTU and its CMakeLists.txt file. Once the tarball WriteVTU.tar has been downloaded and extracted,

    cd WriteVTU/build

If VTK is installed:

    cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

    cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

    make

and run it:

    ./WriteVTU

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.