#include <vtkActor.h>
#include <vtkCallbackCommand.h>
#include <vtkCommand.h>
#include <vtkInteractorStyleTrackballCamera.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSliderRepresentation2D.h>
#include <vtkSliderWidget.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
#include <vtkWidgetEvent.h>
#include <vtkWidgetEventTranslator.h>

// The callback does the work.
// The callback keeps a pointer to the sphere whose resolution is
// controlled. After constructing the callback, the program sets the
// SphereSource of the callback to
// the object to be controlled.
class vtkSliderCallback : public vtkCommand
{
public:
  static vtkSliderCallback* New() { return new vtkSliderCallback; }
  void Execute(vtkObject* caller, unsigned long, void*) override
  {
    vtkSliderWidget* sliderWidget = reinterpret_cast<vtkSliderWidget*>(caller);
    int value = static_cast<int>(
      static_cast<vtkSliderRepresentation*>(sliderWidget->GetRepresentation())->GetValue());
    this->SphereSource->SetPhiResolution(value / 2);
    this->SphereSource->SetThetaResolution(value);
  }
  vtkSliderCallback()
    : SphereSource(nullptr)
  {
  }
  vtkSphereSource* SphereSource;
};

int main(int, char*[])
{
  // A sphere
  vtkSmartPointer<vtkSphereSource> sphereSource = vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(4.0);
  sphereSource->SetPhiResolution(4);
  sphereSource->SetThetaResolution(8);

  vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(sphereSource->GetOutputPort());

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

  // A renderer and render window
  vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  // An interactor
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actors to the scene
  renderer->AddActor(actor);

  // Render an image (lights and cameras are created automatically)
  renderWindow->Render();

  // Here we describe the representation of the widget.
  vtkSmartPointer<vtkSliderRepresentation2D> sliderRep =
    vtkSmartPointer<vtkSliderRepresentation2D>::New();
  sliderRep->SetMinimumValue(3.0);
  sliderRep->SetMaximumValue(20.0);
  sliderRep->SetValue(sphereSource->GetThetaResolution());
  sliderRep->SetTitleText("Sphere Resolution");

  // Here we use normalized display coordinates (0,1) so that the
  // slider will stay in the same proportionate location if the window
  // is resized.
  sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint1Coordinate()->SetValue(.1, .1);
  sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint2Coordinate()->SetValue(.3, .1);

  // Create the callback and pass it the sphereSource to be controlled
  vtkSmartPointer<vtkSliderCallback> callback = vtkSmartPointer<vtkSliderCallback>::New();
  callback->SphereSource = sphereSource;

  // The widget is the controller for the interction.
  vtkSmartPointer<vtkSliderWidget> sliderWidget = vtkSmartPointer<vtkSliderWidget>::New();
  sliderWidget->SetInteractor(renderWindowInteractor);
  sliderWidget->SetRepresentation(sliderRep);
  sliderWidget->SetAnimationModeToAnimate();
  sliderWidget->EnabledOn();

  // Observe the interaction events of the widget. If the computation
  // in the callback is time consuming, observe the
  // EndInteractionEvent instead.
  sliderWidget->AddObserver(vtkCommand::InteractionEvent, callback);

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

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}
