# HighlightPickedActor

VTKExamples/Cxx/Picking/HighlightPickedActor

### Description

Click on a sphere to highlight it.

### Code

HighlightPickedActor.cxx

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

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

        // Pick from this location.
        vtkSmartPointer<vtkPropPicker>  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(1.0, 0.0, 0.0);
          this->LastPickedActor->GetProperty()->SetDiffuse(1.0);
          this->LastPickedActor->GetProperty()->SetSpecular(0.0);
        }

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

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

    vtkStandardNewMacro(MouseInteractorHighLightActor);

    // Execute application.
    int main(int argc, char *argv[])
    {
      int numberOfSpheres = 10;
      if (argc > 1)
      {
        numberOfSpheres = atoi(argv[1]);
      }
      // 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 );

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

      renderWindowInteractor->SetInteractorStyle( style );

      for (int i = 0; i < numberOfSpheres; ++i)
      {
        vtkSmartPointer<vtkSphereSource> 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(.5, 1.0);
        source->SetRadius(radius);
        source->SetCenter(x, y, z);
        source->SetPhiResolution(11);
        source->SetThetaResolution(21);
        vtkSmartPointer<vtkPolyDataMapper> mapper =
          vtkSmartPointer<vtkPolyDataMapper>::New();
        mapper->SetInputConnection ( source->GetOutputPort());
        vtkSmartPointer<vtkActor> actor =
          vtkSmartPointer<vtkActor>::New();
        actor->SetMapper ( mapper );
        double r, g, b;
        r = vtkMath::Random(.4, 1.0);
        g = vtkMath::Random(.4, 1.0);
        b = vtkMath::Random(.4, 1.0);
        actor->GetProperty()->SetDiffuseColor(r, g, b);
        actor->GetProperty()->SetDiffuse(.8);
        actor->GetProperty()->SetSpecular(.5);
        actor->GetProperty()->SetSpecularColor(1.0,1.0,1.0);
        actor->GetProperty()->SetSpecularPower(30.0);
        renderer->AddActor ( actor );
      }

      renderer->SetBackground ( .3, .4, .5 );

      // 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
      vtkCommonCore
      vtkFiltersSources
      vtkInteractionStyle
      vtkRenderingCore
      vtkRenderingFreeType
      vtkRenderingOpenGL2 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.