# NullPoint

VTKExamples/Cxx/PolyData/NullPoint

### Code

NullPoint.cxx

    #include <vtkPoints.h>
    #include <vtkPointData.h>
    #include <vtkPolyData.h>
    #include <vtkSmartPointer.h>
    #include <vtkFloatArray.h>

    int main(int, char *[])
    {
      vtkSmartPointer<vtkPoints> points =
        vtkSmartPointer<vtkPoints>::New();
      points->InsertNextPoint(1,1,1);
      points->InsertNextPoint(2,2,2);
      points->InsertNextPoint(3,3,3);

      vtkSmartPointer<vtkPolyData> polydata =
        vtkSmartPointer<vtkPolyData>::New();
      polydata->SetPoints(points);

      vtkSmartPointer<vtkFloatArray> floatArray =
        vtkSmartPointer<vtkFloatArray>::New();
      floatArray->SetNumberOfValues(3);
      floatArray->SetNumberOfComponents(1);
      floatArray->SetName("FloatArray");
      for(vtkIdType i = 0; i < 3; i++)
      {
        floatArray->SetValue(i,2);
      }
      polydata->GetPointData()->AddArray(floatArray);

      vtkSmartPointer<vtkIntArray> intArray =
        vtkSmartPointer<vtkIntArray>::New();
      intArray->SetNumberOfValues(3);
      intArray->SetNumberOfComponents(1);
      intArray->SetName("IntArray");
      for(vtkIdType i = 0; i < 3; i++)
      {
        intArray->SetValue(i,2);
      }

      polydata->GetPointData()->AddArray(intArray);

      for(vtkIdType i = 0; i < 3; i++)
      {
        double p[3];
        polydata->GetPoint(i,p);
        vtkFloatArray* pointsFloatArray = vtkFloatArray::SafeDownCast(polydata->GetPointData()->GetArray("FloatArray"));
        vtkIntArray* pointsIntArray = vtkIntArray::SafeDownCast(polydata->GetPointData()->GetArray("IntArray"));
        std::cout << "Point " << i << " : " << p[0] << " " << p[1] << " " << p[2] << " "
                  << pointsFloatArray->GetValue(i) << " " << pointsIntArray->GetValue(i) << std::endl;
      }

      polydata->GetPointData()->NullPoint(1);
      polydata->Modified();

      for(vtkIdType i = 0; i < 3; i++)
      {
        double p[3];
        polydata->GetPoint(i,p);
        vtkFloatArray* pointsFloatArray = vtkFloatArray::SafeDownCast(polydata->GetPointData()->GetArray("FloatArray"));
        vtkIntArray* pointsIntArray = vtkIntArray::SafeDownCast(polydata->GetPointData()->GetArray("IntArray"));
        std::cout << "Point " << i << " : " << p[0] << " " << p[1] << " " << p[2] << " "
                  << pointsFloatArray->GetValue(i) << " " << pointsIntArray->GetValue(i) << std::endl;

      }

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(NullPoint)

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

    add_executable(NullPoint MACOSX_BUNDLE NullPoint.cxx)

    target_link_libraries(NullPoint ${VTK_LIBRARIES})

### Download and Build NullPoint

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

    cd NullPoint/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:

    ./NullPoint

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.