# LODProp3D

VTKExamples/Cxx/Visualization/LODProp3D

### Description

If you have a fast graphics card, you may not see a difference.

### Code

LODProp3D.cxx

    #include <vtkSmartPointer.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkLODProp3D.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderer.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkPolyData.h>
    #include <vtkSphereSource.h>
    #include <vtkCallbackCommand.h>
    #include <vtkProperty.h>

    void RefreshCallback( vtkObject* vtkNotUsed(caller),
                          long unsigned int vtkNotUsed(eventId),
                          void* clientData,
                          void* vtkNotUsed(callData) )
    {
      vtkSmartPointer<vtkLODProp3D> lodProp =
        static_cast<vtkLODProp3D*>(clientData);
      std::cout << "Last rendered LOD: " << lodProp->GetLastRenderedLODID() << std::endl;
    }

    int main (int, char *[])
    {
      // High res sphere
      vtkSmartPointer<vtkSphereSource> highResSphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      int res = 100;
      highResSphereSource->SetThetaResolution(res);
      highResSphereSource->SetPhiResolution(res);
      highResSphereSource->Update();

      vtkSmartPointer<vtkPolyDataMapper> highResMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      highResMapper->SetInputConnection(highResSphereSource->GetOutputPort());

      // Low res sphere
      vtkSmartPointer<vtkSphereSource> lowResSphereSource =
        vtkSmartPointer<vtkSphereSource>::New();

      vtkSmartPointer<vtkPolyDataMapper> lowResMapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      lowResMapper->SetInputConnection(lowResSphereSource->GetOutputPort());

      vtkSmartPointer<vtkProperty> propertyLowRes =
        vtkSmartPointer<vtkProperty>::New();
      propertyLowRes->SetDiffuseColor(0.89, 0.81, 0.34);
      propertyLowRes->SetInterpolationToFlat();

      vtkSmartPointer<vtkProperty> propertyHighRes =
        vtkSmartPointer<vtkProperty>::New();
      propertyHighRes->SetDiffuseColor(1.0, 0.3882, 0.2784);
      propertyHighRes->SetInterpolationToFlat();

      vtkSmartPointer<vtkLODProp3D> prop =
          vtkSmartPointer<vtkLODProp3D>::New();
      prop->AddLOD(lowResMapper, propertyLowRes, 0.0);
      prop->AddLOD(highResMapper, propertyHighRes, 0.0);

      std::cout << "There are " << prop->GetNumberOfLODs() << " LODs" << std::endl;

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

      //prop->SetAllocatedRenderTime(1e-6,renderer);
      prop->SetAllocatedRenderTime(1e-10,renderer);

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

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

      vtkSmartPointer<vtkCallbackCommand> refreshCallback =
        vtkSmartPointer<vtkCallbackCommand>::New();
      refreshCallback->SetCallback (RefreshCallback);
      refreshCallback->SetClientData(prop);

      renderWindow->AddObserver(vtkCommand::ModifiedEvent,refreshCallback);

      renderWindow->Render();

      // Begin mouse interaction
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(LODProp3D)

    find_package(VTK COMPONENTS
      vtkCommonCore
      vtkCommonDataModel
      vtkFiltersSources
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping LODProp3D: ${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(LODProp3D MACOSX_BUNDLE LODProp3D.cxx )
      target_link_libraries(LODProp3D PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(LODProp3D MACOSX_BUNDLE LODProp3D.cxx )
      target_link_libraries(LODProp3D PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS LODProp3D
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build LODProp3D

Click here to download LODProp3D and its CMakeLists.txt file. Once the tarball LODProp3D.tar has been downloaded and extracted,

    cd LODProp3D/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:

    ./LODProp3D

WINDOWS USERS

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