#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkPointData.h>
#include <vtkReverseSense.h>
#include <vtkFloatArray.h>

int main(int, char *[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->Update();

  vtkSmartPointer<vtkFloatArray> pointNormals =
    vtkFloatArray::SafeDownCast(sphereSource->GetOutput()->GetPointData()->GetNormals());

  std::cout << std::endl << "Normals: " << std::endl;
  // Display the first few normals
  for(unsigned int i = 0; i < 5; i++)
  {
    double pN[3];
    pointNormals->GetTuple(i, pN);
    std::cout << "Point normal " << i << ": " << pN[0] << " " << pN[1] << " " << pN[2] << std::endl;
  }

  vtkSmartPointer<vtkReverseSense> reverseSense =
    vtkSmartPointer<vtkReverseSense>::New();
  reverseSense->SetInputConnection(sphereSource->GetOutputPort());
  reverseSense->ReverseNormalsOn();
  reverseSense->Update();


  vtkSmartPointer<vtkFloatArray> reversedNormals =
    vtkFloatArray::SafeDownCast(reverseSense->GetOutput()->GetPointData()->GetNormals());

  std::cout << std::endl << "Reversed: " << std::endl;
  // Display the first few normals to verify that they are flipped
  for(unsigned int i = 0; i < 5; i++)
  {
    double pN[3];
    reversedNormals->GetTuple(i, pN);
    std::cout << "Reversed normal " << i << ": " << pN[0] << " " << pN[1] << " " << pN[2] << std::endl;
  }

  return EXIT_SUCCESS;
}
