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# HighlightPickedActor

VTKEx/Cxx/Picking/HighlightPickedActor

### Description

Click on a sphere to highlight it. The picked sphere color changes to red, and its EdgeVisibity is On. The example subclasses vtkInteractorStyleTrackballCamera with a local class called MouseInteractorHighLightActor. The new interactor overrides the OnLeftButtonDown of vtkInteractorStyleTrackballCamera.

Seealso

HighlightWithSilhouette generates a silhouette of the picked actor.

Other languages

See (Python)

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

HighlightPickedActor.cxx

    #include <vtkActor.h>
    #include <vtkInteractorStyleTrackballCamera.h>
    #include <vtkMath.h>
    #include <vtkNamedColors.h>
    #include <vtkObjectFactory.h>
    #include <vtkPolyDataMapper.h>
    #include <vtkPropPicker.h>
    #include <vtkProperty.h>
    #include <vtkRenderWindow.h>
    #include <vtkRenderWindowInteractor.h>
    #include <vtkRenderer.h>
    #include <vtkSmartPointer.h>
    #include <vtkSphereSource.h>

    namespace
    {
    // Handle mouse events
    class MouseInteractorHighLightActor : public vtkInteractorStyleTrackballCamera
    {
    public:
      static MouseInteractorHighLightActor* New();
      vtkTypeMacro(MouseInteractorHighLightActor,
                   vtkInteractorStyleTrackballCamera);

      MouseInteractorHighLightActor()
      {
        LastPickedActor = NULL;
        LastPickedProperty = vtkProperty::New();
      }
      virtual ~MouseInteractorHighLightActor()
      {
        LastPickedProperty->Delete();
      }
      virtual void OnLeftButtonDown() override
      {
        auto colors =   vtkSmartPointer<vtkNamedColors>::New();

        int* clickPos = this->GetInteractor()->GetEventPosition();

        // Pick from this location.
        auto picker =
            vtkSmartPointer<vtkPropPicker>::New();
        picker->Pick(clickPos[0], clickPos[1], 0, this->GetDefaultRenderer());

        // If we picked something before, reset its property
        if (this->LastPickedActor)
        {
          this->LastPickedActor->GetProperty()->DeepCopy(this->LastPickedProperty);
        }
        this->LastPickedActor = picker->GetActor();
        if (this->LastPickedActor)
        {
          // Save the property of the picked actor so that we can
          // restore it next time
          this->LastPickedProperty->DeepCopy(this->LastPickedActor->GetProperty());
          // Highlight the picked actor by changing its properties
          this->LastPickedActor->GetProperty()->SetColor(
              colors->GetColor3d("Red").GetData());
          this->LastPickedActor->GetProperty()->SetDiffuse(1.0);
          this->LastPickedActor->GetProperty()->SetSpecular(0.0);
          this->LastPickedActor->GetProperty()->EdgeVisibilityOn();
        }

        // Forward events
        vtkInteractorStyleTrackballCamera::OnLeftButtonDown();
      }

    private:
      vtkActor* LastPickedActor;
      vtkProperty* LastPickedProperty;
    };
    }

    vtkStandardNewMacro(MouseInteractorHighLightActor);

    // Execute application.
    int main(int argc, char* argv[])
    {
      auto colors =
          vtkSmartPointer<vtkNamedColors>::New();

      colors->SetColor("Bkg", 0.3, 0.4, 0.5);

      int numberOfSpheres = 10;
      if (argc > 1)
      {
        numberOfSpheres = atoi(argv[1]);
      }
      // A renderer and render window
      auto renderer =
          vtkSmartPointer<vtkRenderer>::New();
      auto renderWindow =
          vtkSmartPointer<vtkRenderWindow>::New();
      renderWindow->SetSize(640, 480);
      renderWindow->AddRenderer(renderer);

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

      // Set the custom type to use for interaction.
      auto style =
          vtkSmartPointer<MouseInteractorHighLightActor>::New();
      style->SetDefaultRenderer(renderer);

      renderWindowInteractor->SetInteractorStyle(style);

      for (int i = 0; i < numberOfSpheres; ++i)
      {
        auto source =
            vtkSmartPointer<vtkSphereSource>::New();
        double x, y, z, radius;
        x = vtkMath::Random(-5, 5);
        y = vtkMath::Random(-5, 5);
        z = vtkMath::Random(-5, 5);
        radius = vtkMath::Random(0.5, 1.0);
        source->SetRadius(radius);
        source->SetCenter(x, y, z);
        source->SetPhiResolution(11);
        source->SetThetaResolution(21);
        auto mapper =
            vtkSmartPointer<vtkPolyDataMapper>::New();
        mapper->SetInputConnection(source->GetOutputPort());
        auto actor =
            vtkSmartPointer<vtkActor>::New();
        actor->SetMapper(mapper);
        double r, g, b;
        r = vtkMath::Random(0.4, 1.0);
        g = vtkMath::Random(0.4, 1.0);
        b = vtkMath::Random(0.4, 1.0);
        actor->GetProperty()->SetDiffuseColor(r, g, b);
        actor->GetProperty()->SetDiffuse(0.8);
        actor->GetProperty()->SetSpecular(0.5);
        actor->GetProperty()->SetSpecularColor(
            colors->GetColor3d("White").GetData());
        actor->GetProperty()->SetSpecularPower(30.0);
        renderer->AddActor(actor);
      }

      renderer->SetBackground(colors->GetColor3d("Bkg").GetData());

      // Render and interact
      renderWindow->Render();
      renderWindowInteractor->Initialize();
      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

    project(HighlightPickedActor)

    find_package(VTK COMPONENTS
      vtkvtkCommonColor
      vtkvtkCommonCore
      vtkvtkFiltersSources
      vtkvtkInteractionStyle
      vtkvtkRenderingContextOpenGL2
      vtkvtkRenderingCore
      vtkvtkRenderingFreeType
      vtkvtkRenderingGL2PSOpenGL2
      vtkvtkRenderingOpenGL2 QUIET)
    if (NOT VTK_FOUND)
      message("Skipping HighlightPickedActor: ${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(HighlightPickedActor MACOSX_BUNDLE HighlightPickedActor.cxx )
      target_link_libraries(HighlightPickedActor PRIVATE ${VTK_LIBRARIES})
    else ()
      # include all components
      add_executable(HighlightPickedActor MACOSX_BUNDLE HighlightPickedActor.cxx )
      target_link_libraries(HighlightPickedActor PRIVATE ${VTK_LIBRARIES})
      # vtk_module_autoinit is needed
      vtk_module_autoinit(
        TARGETS HighlightPickedActor
        MODULES ${VTK_LIBRARIES}
        )
    endif ()

### Download and Build HighlightPickedActor

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

    cd HighlightPickedActor/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:

    ./HighlightPickedActor

WINDOWS USERS

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