# ReadUnstructuredGrid

VTKExamples/Cxx/IO/ReadUnstructuredGrid

### Description

This examples demonstrates how to read an unstructured grid (VTU) file.

An example data file (.vtu) for testing can be found in VTKData/Data/quadraticTetra01.vtu.

### Code

ReadUnstructuredGrid.cxx

    #include <vtkXMLUnstructuredGridReader.h>
    #include <vtkSmartPointer.h>
    #include <vtkDataSetMapper.h>
    #include <vtkActor.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.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();

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

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

      //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(.3, .6, .3); // Background color green

      //Render and interact
      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 PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.