OctreeVisualize

#include <vtkActor.h>
#include <vtkCommand.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkOctreePointLocator.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkProperty2D.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSliderRepresentation2D.h>
#include <vtkSliderWidget.h>
#include <vtkSphereSource.h>
#include <vtkTextProperty.h>

#include <cmath>

namespace {
class vtkSliderCallback : public vtkCommand
{
public:
  static vtkSliderCallback* New()

  {
    return new vtkSliderCallback;
  }
  vtkSliderCallback() : Octree(0), Level(0), PolyData(0), Renderer(0)
  {
  }

  virtual void Execute(vtkObject* caller, unsigned long, void*)
  {
    vtkSliderWidget* sliderWidget = reinterpret_cast<vtkSliderWidget*>(caller);
    this->Level = vtkMath::Round(
        static_cast<vtkSliderRepresentation*>(sliderWidget->GetRepresentation())
            ->GetValue());

    this->Octree->GenerateRepresentation(this->Level, this->PolyData);
    this->Renderer->Render();
  }

  vtkOctreePointLocator* Octree;
  int Level;
  vtkPolyData* PolyData;
  vtkRenderer* Renderer;
};
} // namespace

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Create a point cloud
  vtkNew<vtkSphereSource> pointSource;
  pointSource->SetPhiResolution(50);
  pointSource->SetThetaResolution(50);
  vtkNew<vtkPolyDataMapper> pointsMapper;
  pointsMapper->SetInputConnection(pointSource->GetOutputPort());
  pointSource->Update();
  vtkNew<vtkActor> pointsActor;
  pointsActor->SetMapper(pointsMapper);
  pointsActor->GetProperty()->SetInterpolationToFlat();
  pointsActor->GetProperty()->SetRepresentationToPoints();
  pointsActor->GetProperty()->SetColor(colors->GetColor4d("Yellow").GetData());

  // Create the tree
  vtkNew<vtkOctreePointLocator> octree;
  octree->SetMaximumPointsPerRegion(5);
  octree->SetDataSet(pointSource->GetOutput());
  octree->BuildLocator();

  vtkNew<vtkPolyData> polydata;
  octree->GenerateRepresentation(0, polydata);

  vtkNew<vtkPolyDataMapper> octreeMapper;
  octreeMapper->SetInputData(polydata);

  vtkNew<vtkActor> octreeActor;
  octreeActor->SetMapper(octreeMapper);
  octreeActor->GetProperty()->SetInterpolationToFlat();
  octreeActor->GetProperty()->SetRepresentationToWireframe();
  octreeActor->GetProperty()->SetColor(
      colors->GetColor4d("SpringGreen").GetData());

  // A renderer and render window
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);

  // An interactor
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actors to the scene
  renderer->AddActor(pointsActor);
  renderer->AddActor(octreeActor);
  renderer->SetBackground(colors->GetColor3d("MidnightBlue").GetData());

  // Render an image (lights and cameras are created automatically)
  renderWindow->SetWindowName("OctreeVisualize");
  renderWindow->SetSize(600, 600);
  renderWindow->Render();

  vtkNew<vtkSliderRepresentation2D> sliderRep;
  sliderRep->SetMinimumValue(0);
  sliderRep->SetMaximumValue(octree->GetLevel());
  sliderRep->SetValue(0);
  sliderRep->SetTitleText("Level");
  sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint1Coordinate()->SetValue(.2, .2);
  sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint2Coordinate()->SetValue(.8, .2);
  sliderRep->SetSliderLength(0.075);
  sliderRep->SetSliderWidth(0.05);
  sliderRep->SetEndCapLength(0.05);
  sliderRep->GetTitleProperty()->SetColor(
      colors->GetColor3d("Beige").GetData());
  sliderRep->GetCapProperty()->SetColor(
      colors->GetColor3d("MistyRose").GetData());
  sliderRep->GetSliderProperty()->SetColor(
      colors->GetColor3d("LightBlue").GetData());
  sliderRep->GetSelectedProperty()->SetColor(
      colors->GetColor3d("Violet").GetData());

  vtkNew<vtkSliderWidget> sliderWidget;
  sliderWidget->SetInteractor(renderWindowInteractor);
  sliderWidget->SetRepresentation(sliderRep);
  sliderWidget->SetAnimationModeToAnimate();
  sliderWidget->EnabledOn();

  vtkNew<vtkSliderCallback> callback;
  callback->Octree = octree;
  callback->PolyData = polydata;
  callback->Renderer = renderer;

  sliderWidget->AddObserver(vtkCommand::InteractionEvent, callback);

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

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(OctreeVisualize)

find_package(VTK COMPONENTS 
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "OctreeVisualize: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(OctreeVisualize MACOSX_BUNDLE OctreeVisualize.cxx )
  target_link_libraries(OctreeVisualize PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS OctreeVisualize
  MODULES ${VTK_LIBRARIES}
)

cd OctreeVisualize/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./OctreeVisualize