# Slider2D

VTKExamples/Cxx/Widgets/Slider2D

### Description

This example demonstrates how to use a slider that is drawn in window coordinates - so if you move the scene the slider is not affected. Contrast this with the 3D slider widget that remains at a fixed location in the world coordinates.

If the callback is connected to InteractionEvent, the scene will update immediately. This is not ideal if the re-rendering takes significant time as it will make the interaction very choppy. If you want to move the slider and have the scene update when the mouse button is released, connect the callback to EndInteractionEvent instead.

### Code

Slider2D.cxx

    #include <vtkSphereSource.h>
    #include <vtkTextProperty.h>
    #include <vtkProperty2D.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 <vtkSphereSource.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>

    // This does the actual work.
    // Callback for the interaction
    class vtkSliderCallback : public vtkCommand
    {
    public:
      static vtkSliderCallback *New()
      {
        return new vtkSliderCallback;
      }
      virtual void Execute(vtkObject *caller, unsigned long, void*)
      {
        vtkSliderWidget *sliderWidget =
          reinterpret_cast<vtkSliderWidget*>(caller);
        this->SphereSource->SetPhiResolution(static_cast<vtkSliderRepresentation *>(sliderWidget->GetRepresentation())->GetValue());
        this->SphereSource->SetThetaResolution(static_cast<vtkSliderRepresentation *>(sliderWidget->GetRepresentation())->GetValue());
      }
      vtkSliderCallback():SphereSource(0) {}
      vtkSphereSource *SphereSource;
    };

    int main (int, char *[])
    {
      // A sphere
      vtkSmartPointer<vtkSphereSource> sphereSource =
        vtkSmartPointer<vtkSphereSource>::New();
      sphereSource->SetCenter(0.0, 0.0, 0.0);
      sphereSource->SetRadius(4.0);

      vtkSmartPointer<vtkPolyDataMapper> mapper =
        vtkSmartPointer<vtkPolyDataMapper>::New();
      mapper->SetInputConnection(sphereSource->GetOutputPort());

      vtkSmartPointer<vtkActor> actor =
        vtkSmartPointer<vtkActor>::New();
      actor->SetMapper(mapper);
      actor->GetProperty()->SetInterpolationToFlat();

      // 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(actor);

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

      vtkSmartPointer<vtkSliderRepresentation2D> sliderRep =
        vtkSmartPointer<vtkSliderRepresentation2D>::New();

      sliderRep->SetMinimumValue(3.0);
      sliderRep->SetMaximumValue(20.0);
      sliderRep->SetValue(5.0);
      sliderRep->SetTitleText("Sphere Resolution");

      // Set color properties:
      // Change the color of the knob that slides
      sliderRep->GetSliderProperty()->SetColor(1,0,0);//red

      // Change the color of the text indicating what the slider controls
      sliderRep->GetTitleProperty()->SetColor(1,0,0);//red

      // Change the color of the text displaying the value
      sliderRep->GetLabelProperty()->SetColor(1,0,0);//red

      // Change the color of the knob when the mouse is held on it
      sliderRep->GetSelectedProperty()->SetColor(0,1,0);//green

      // Change the color of the bar
      sliderRep->GetTubeProperty()->SetColor(1,1,0);//yellow

      // Change the color of the ends of the bar
      sliderRep->GetCapProperty()->SetColor(1,1,0);//yellow

      sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToDisplay();
      sliderRep->GetPoint1Coordinate()->SetValue(40 ,40);
      sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToDisplay();
      sliderRep->GetPoint2Coordinate()->SetValue(100, 40);

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

      vtkSmartPointer<vtkSliderCallback> callback =
        vtkSmartPointer<vtkSliderCallback>::New();
      callback->SphereSource = sphereSource;

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

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

      renderWindowInteractor->Start();

      return EXIT_SUCCESS;
    }

### CMakeLists.txt

    cmake_minimum_required(VERSION 2.8)

    PROJECT(Slider2D)

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

    add_executable(Slider2D MACOSX_BUNDLE Slider2D.cxx )

    target_link_libraries(Slider2D ${VTK_LIBRARIES})

### Download and Build Slider2D

Click here to download Slider2D and its CMakeLists.txt file. Once the tarball Slider2D.tar has been downloaded and extracted,

    cd Slider2D/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:

    ./Slider2D

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.