# ReadUnstructuredGrid

VTKExamples/Cxx/IO/ReadUnstructuredGrid

### Description

This example demonstrates how to read an unstructured grid (VTU) file. The front facing faces are colored white, while the back facing faces are colored red.

An example data file (.vtu) for testing can be found in VTKExamples/src/TestingData/tetra.vtu.

### Code

ReadUnstructuredGrid.cxx

    #include <vtkSmartPointer.h>
    #include <vtkXMLUnstructuredGridReader.h>

    #include <vtkDataSetMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkProperty.h>
    #include <vtkNamedColors.h>

    int main ( int argc, char *argv[] )
    {
      //parse command line arguments
      if(argc < 2)
      {
        std::cerr << "Usage: " << argv[0]
                  << " Filename(.vtu)" << std::endl;
        return EXIT_FAILURE;
      }

      std::string filename = argv[1];

      //read all the data from the file
      vtkSmartPointer<vtkXMLUnstructuredGridReader> reader =
        vtkSmartPointer<vtkXMLUnstructuredGridReader>::New();
      reader->SetFileName(filename.c_str());
      reader->Update();

      vtkSmartPointer<vtkNamedColors> colors =
        vtkSmartPointer<vtkNamedColors>::New();

      //Create a mapper and actor
      vtkSmartPointer<vtkDataSetMapper> mapper =
        vtkSmartPointer<vtkDataSetMapper>::New();
      mapper->SetInputConnection(reader->GetOutputPort());
      mapper->ScalarVisibilityOff();

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->EdgeVisibilityOn();
      actor->GetProperty()->SetLineWidth(2.0);

      vtkSmartPointer<vtkProperty> backFace =
        vtkSmartPointer<vtkProperty>::New();
      backFace->SetColor(colors->GetColor3d("tomato").GetData());
      actor->SetBackfaceProperty(backFace);

      //Create a renderer, render window, and interactor
      vtkSmartPointer<vtkRenderer> renderer =
        vtkSmartPointer<vtkRenderer>::New();
      vtkSmartPointer<vtkRenderWindow> renderWindow =
        vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->AddRenderer(renderer);
      vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
        vtkSmartPointer<vtkRenderWindowInteractor>::New();
      renderWindowInteractor->SetRenderWindow(renderWindow);

      //Add the actor to the scene
      renderer->AddActor(actor);
      renderer->SetBackground(colors->GetColor3d("Wheat").GetData());

      //Render and interact
      renderWindow->SetSize(640, 480);

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

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(ReadUnstructuredGrid)

    find_package(VTK REQUIRED)
    include(${VTK_USE_FILE})

    add_executable(ReadUnstructuredGrid MACOSX_BUNDLE ReadUnstructuredGrid.cxx )

    target_link_libraries(ReadUnstructuredGrid ${VTK_LIBRARIES})

### Download and Build ReadUnstructuredGrid

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

    cd ReadUnstructuredGrid/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:

    ./ReadUnstructuredGrid

WINDOWS USERS

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