# VisualizeKDTree

VTKExamples/Cxx/DataStructures/VisualizeKDTree

### Description

This demo shows every level of a kdTree.

### Code

VisualizeKDTree.cxx

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

    class vtkSliderCallback : public vtkCommand
    {
    public:
      static vtkSliderCallback *New()
      {
        return new vtkSliderCallback;
      }
      vtkSliderCallback():KdTree(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->KdTree->GenerateRepresentation(this->Level, this->PolyData);
        this->Renderer->Render();
      }

      vtkKdTreePointLocator* KdTree;
      int Level;
      vtkPolyData* PolyData;
      vtkRenderer* Renderer;
    };

    int main (int, char *[])
    {
      // Create a point cloud
      vtkSmartPointer<vtkPointSource> pointSource =
        vtkSmartPointer<vtkPointSource>::New();
      pointSource->SetRadius(4);
      pointSource->SetNumberOfPoints(1000);
      pointSource->Update();

      vtkSmartPointer<vtkPolyDataMapper> pointsMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      pointsMapper->SetInputConnection(pointSource->GetOutputPort());

      vtkSmartPointer<vtkActor> pointsActor =
        vtkSmartPointer<vtkActor>::New();
      pointsActor->SetMapper(pointsMapper);
      pointsActor->GetProperty()->SetInterpolationToFlat();

      int maxLevel = 20;
      // Create the tree
      vtkSmartPointer<vtkKdTreePointLocator> kdTree =
        vtkSmartPointer<vtkKdTreePointLocator>::New();
      kdTree->SetDataSet(pointSource->GetOutput());
      kdTree->AutomaticOff();
      kdTree->SetMaxLevel(maxLevel);
      kdTree->BuildLocator();

      // Initialize the representation
      vtkSmartPointer<vtkPolyData> polydata =
        vtkSmartPointer<vtkPolyData>::New();
      kdTree->GenerateRepresentation(0, polydata);

      vtkSmartPointer<vtkPolyDataMapper> octreeMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
    #if VTK_MAJOR_VERSION <= 5
      octreeMapper->SetInputConnection(polydata->GetProducerPort());
    #else
      octreeMapper->SetInputData(polydata);
    #endif

      vtkSmartPointer<vtkActor> octreeActor =
        vtkSmartPointer<vtkActor>::New();
      octreeActor->SetMapper(octreeMapper);
      octreeActor->GetProperty()->SetInterpolationToFlat();
      octreeActor->GetProperty()->SetRepresentationToWireframe();

      // 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(pointsActor);
      renderer->AddActor(octreeActor);

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

      vtkSmartPointer<vtkSliderRepresentation2D> sliderRep =
        vtkSmartPointer<vtkSliderRepresentation2D>::New();
      sliderRep->SetMinimumValue(0);
      sliderRep->SetMaximumValue(kdTree->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);

      vtkSmartPointer<vtkSliderWidget> sliderWidget =
        vtkSmartPointer<vtkSliderWidget>::New();
      sliderWidget->SetInteractor(renderWindowInteractor);
      sliderWidget->SetRepresentation(sliderRep);
      sliderWidget->SetAnimationModeToAnimate();
      sliderWidget->EnabledOn();

      vtkSmartPointer<vtkSliderCallback> callback =
        vtkSmartPointer<vtkSliderCallback>::New();
      callback->KdTree = kdTree;
      callback->PolyData = polydata;
      callback->Renderer = renderer;

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

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

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(VisualizeKDTree)

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

    add_executable(VisualizeKDTree MACOSX_BUNDLE VisualizeKDTree.cxx )

    target_link_libraries(VisualizeKDTree ${VTK_LIBRARIES})

### Download and Build VisualizeKDTree

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

    cd VisualizeKDTree/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:

    ./VisualizeKDTree

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.