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# VisualizeOBBTree

VTKEx/Cxx/DataStructures/VisualizeOBBTree

### Description

This demo displays level of a vtkOBBTree using a slider. An OBBTree is an Oriented Bounding Box Tree. It is used in fast intersection tests, collision detection.

Here's he embeded video:

Seealso

VisualizeKDTree and VisualizeModifiedBSPTree.

Question

If you have a simple question about this example contact us at VTKExProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

### Code

VisualizeOBBTree.cxx

    #include <vtkActor.h>
    #include <vtkOBBTree.h>

    #include <vtkCallbackCommand.h>
    #include <vtkCommand.h>
    #include <vtkSliderRepresentation2D.h>
    #include <vtkSliderWidget.h>

    #include <vtkInteractorStyleTrackballCamera.h>
    #include <vtkPointSource.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 <vtkSmartPointer.h>
    #include <vtkSphereSource.h>
    #include <vtkTextProperty.h>
    #include <vtkWidgetEvent.h>
    #include <vtkWidgetEventTranslator.h>

    #include <vtkBYUReader.h>
    #include <vtkOBJReader.h>
    #include <vtkPLYReader.h>
    #include <vtkPolyDataReader.h>
    #include <vtkSTLReader.h>
    #include <vtkXMLPolyDataReader.h>

    #include <vtkMath.h>
    #include <vtkNamedColors.h>

    #include <vtksys/SystemTools.hxx>

    namespace
    {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char *fileName);
    }

    namespace {
    class vtkSliderCallback : public vtkCommand {
    public:
      static vtkSliderCallback *New() { return new vtkSliderCallback; }

      vtkSliderCallback() : OBBTree(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->OBBTree->GenerateRepresentation(this->Level, this->PolyData);
        this->Renderer->Render();
      }

      vtkOBBTree *OBBTree;
      int Level;
      vtkPolyData *PolyData;
      vtkRenderer *Renderer;
    };
    } // namespace

    int main(int argc, char *argv[]) {

      auto polyData = ReadPolyData(argc > 1 ? argv[1] : "");;

      auto colors = vtkSmartPointer<vtkNamedColors>::New();

      auto pointsMapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
      pointsMapper->SetInputData(polyData);
      pointsMapper->ScalarVisibilityOff();

      auto pointsActor = vtkSmartPointer<vtkActor>::New();
      pointsActor->SetMapper(pointsMapper);
      pointsActor->GetProperty()->SetInterpolationToFlat();
      pointsActor->GetProperty()->SetColor(colors->GetColor4d("Yellow").GetData());
      pointsActor->GetProperty()->SetOpacity(.3);

      int maxLevel = 5;
      // Create the tree
      auto obbTree = vtkSmartPointer<vtkOBBTree>::New();
      obbTree->SetDataSet(polyData);
      obbTree->SetMaxLevel(maxLevel);
      obbTree->BuildLocator();

      double corner[3] = {0.0, 0.0 ,0.0};
      double max[3] = {0.0, 0.0 ,0.0};
      double mid[3] = {0.0, 0.0, 0.0};
      double min[3] = {0.0, 0.0, 0.0};
      double size[3] = {0.0, 0.0, 0.0};

      obbTree->ComputeOBB(polyData, corner, max, mid, min, size);

      std::cout << "Corner:\t"
                << corner[0] << ", " << corner[1] << ", " << corner[2] << std::endl
                << "Max:\t"
                << max[0] << ", " << max[1] << ", " << max[2] << std::endl
                << "Mid:\t"
                << mid[0] << ", " << mid[1] << ", " << mid[2] << std::endl
                << "Min:\t"
                << min[0] << ", " << min[1] << ", " << min[2] << std::endl
                << "Size:\t"
                << size[0] << ", " << size[1] << ", " << size[2] << std::endl;

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

      auto obbtreeMapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
      obbtreeMapper->SetInputData(polydata);

      auto obbtreeActor = vtkSmartPointer<vtkActor>::New();
      obbtreeActor->SetMapper(obbtreeMapper);
      obbtreeActor->GetProperty()->SetInterpolationToFlat();
      obbtreeActor->GetProperty()->SetOpacity(.5);
      obbtreeActor->GetProperty()->EdgeVisibilityOn();
      obbtreeActor->GetProperty()->SetColor(
          colors->GetColor4d("SpringGreen").GetData());

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

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

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

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

      auto sliderRep =
          vtkSmartPointer<vtkSliderRepresentation2D>::New();
      sliderRep->SetMinimumValue(0);
      sliderRep->SetMaximumValue(obbTree->GetLevel());
      sliderRep->SetValue(obbTree->GetLevel() / 2);
      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());

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

      auto callback =
          vtkSmartPointer<vtkSliderCallback>::New();
      callback->OBBTree = obbTree;
      callback->PolyData = polydata;
      callback->Renderer = renderer;
      callback->Execute(sliderWidget, 0, 0);

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

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

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

    namespace
    {
    vtkSmartPointer<vtkPolyData> ReadPolyData(const char *fileName)
    {
      vtkSmartPointer<vtkPolyData> polyData;
      std::string extension = vtksys::SystemTools::GetFilenameLastExtension(std::string(fileName));
      if (extension == ".ply")
      {
        vtkSmartPointer<vtkPLYReader> reader =
          vtkSmartPointer<vtkPLYReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtp")
      {
        vtkSmartPointer<vtkXMLPolyDataReader> reader =
          vtkSmartPointer<vtkXMLPolyDataReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".obj")
      {
        vtkSmartPointer<vtkOBJReader> reader =
          vtkSmartPointer<vtkOBJReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".stl")
      {
        vtkSmartPointer<vtkSTLReader> reader =
          vtkSmartPointer<vtkSTLReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".vtk")
      {
        vtkSmartPointer<vtkPolyDataReader> reader =
          vtkSmartPointer<vtkPolyDataReader>::New();
        reader->SetFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else if (extension == ".g")
      {
        vtkSmartPointer<vtkBYUReader> reader =
          vtkSmartPointer<vtkBYUReader>::New();
        reader->SetGeometryFileName (fileName);
        reader->Update();
        polyData = reader->GetOutput();
      }
      else
      {
        vtkSmartPointer<vtkSphereSource> source =
          vtkSmartPointer<vtkSphereSource>::New();
        source->Update();
        polyData = source->GetOutput();
      }
      return polyData;
    }
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(VisualizeOBBTree)

    find_package(VTK COMPONENTS
      vtkCommonColor
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersGeneral
      vtkFiltersSources
      vtkIOGeometry
      vtkIOLegacy
      vtkIOPLY
      vtkIOXML
      vtkInteractionStyle
      vtkInteractionWidgets
      vtkRenderingContextOpenGL2
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingGL2PSOpenGL2
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping VisualizeOBBTree: ${VTK_NOT_FOUND_MESSAGE}")
      return ()
    endif()
    message (STATUS "VTK_VERSION: ${VTK_VERSION}")
    if (VTK_VERSION VERSION_LESS "8.90.0")
      # old system
      include(${VTK_USE_FILE})
      add_executable(VisualizeOBBTree MACOSX_BUNDLE VisualizeOBBTree.cxx )
      target_link_libraries(VisualizeOBBTree PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(VisualizeOBBTree MACOSX_BUNDLE VisualizeOBBTree.cxx )
      target_link_libraries(VisualizeOBBTree PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS VisualizeOBBTree
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build VisualizeOBBTree

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

    cd VisualizeOBBTree/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:

    ./VisualizeOBBTree

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.