#include <vtkIntArray.h>
#include <vtkNew.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkThresholdPoints.h>

#include <iostream>
#include <string>

int main(int, char*[])
{
  vtkNew<vtkPoints> points;
  points->InsertNextPoint(0, 0, 0);
  points->InsertNextPoint(1, 1, 1);
  points->InsertNextPoint(2, 2, 2);
  points->InsertNextPoint(3, 3, 3);
  points->InsertNextPoint(4, 4, 4);

  std::cout << "There are " << points->GetNumberOfPoints()
            << " points before thresholding." << std::endl;

  // Setup position index.
  vtkNew<vtkIntArray> index;
  index->SetNumberOfComponents(1);
  index->SetName("index");
  index->InsertNextValue(0);
  index->InsertNextValue(1);
  index->InsertNextValue(2);
  index->InsertNextValue(3);
  index->InsertNextValue(4);

  vtkNew<vtkPolyData> polydata;
  polydata->SetPoints(points);
  polydata->GetPointData()->AddArray(index);

  vtkNew<vtkThresholdPoints> threshold;
  threshold->SetInputData(polydata);
  threshold->ThresholdByLower(2);
  threshold->SetInputArrayToProcess(
      0, 0, 0, vtkDataObject::FIELD_ASSOCIATION_POINTS, "index");
  threshold->Update();

  // vtkPolyData* thresholdedPolydata = threshold->GetOutput();
  vtkPolyData* thresholdedPolydata = threshold->GetOutput();
  std::cout << "There are " << thresholdedPolydata->GetNumberOfPoints()
            << " points after thresholding." << std::endl;
  for (vtkIdType i = 0; i < thresholdedPolydata->GetNumberOfPoints(); i++)
  {
    double p[3];
    thresholdedPolydata->GetPoint(i, p);
    std::cout << "Point " << i << " : " << p[0] << " " << p[1] << " " << p[2]
              << std::endl;
  }

  return EXIT_SUCCESS;
}
