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.

Note

This original source code for this example is here.

Question

If you have a question about this example, please use the VTK Discourse Forum

Code¶

Slider2D.cxx

#include <vtkActor.h>
#include <vtkCallbackCommand.h>
#include <vtkNamedColors.h>
#include <vtkNew.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 <vtkSphereSource.h>
#include <vtkTextProperty.h>

namespace {
// This does the actual work.
// Callback for the interaction.
class vtkSliderCallback : public vtkCallbackCommand
{
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;
};
} // namespace

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // A sphere.
  vtkNew<vtkSphereSource> sphereSource;
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(4.0);

  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(sphereSource->GetOutputPort());

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);
  actor->GetProperty()->SetInterpolationToFlat();
  actor->GetProperty()->SetColor(colors->GetColor3d("MistyRose").GetData());
  actor->GetProperty()->SetEdgeColor(colors->GetColor3d("Tomato").GetData());
  actor->GetProperty()->EdgeVisibilityOn();

  // A renderer and render window.
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("Slider2D");
  renderWindow->SetSize(640, 480);

  // An interactor
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);

  // Add the actors to the scene.
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());

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

  vtkNew<vtkSliderRepresentation2D> sliderRep;

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

  // Set color properties:
  //   // Set color properties:
  // Change the color of the knob that slides
  sliderRep->GetSliderProperty()->SetColor(
      colors->GetColor3d("Green").GetData());
  // Change the color of the text indicating what the slider controls
  sliderRep->GetTitleProperty()->SetColor(
      colors->GetColor3d("AliceBlue").GetData());
  // Change the color of the text displaying the value
  sliderRep->GetLabelProperty()->SetColor(
      colors->GetColor3d("AliceBlue").GetData());
  // Change the color of the knob when the mouse is held on it
  sliderRep->GetSelectedProperty()->SetColor(
      colors->GetColor3d("DeepPink").GetData());
  // Change the color of the bar
  sliderRep->GetTubeProperty()->SetColor(
      colors->GetColor3d("MistyRose").GetData());
  // Change the color of the ends of the bar
  sliderRep->GetCapProperty()->SetColor(colors->GetColor3d("Yellow").GetData());
  sliderRep->SetSliderLength(0.05);
  sliderRep->SetSliderWidth(0.025);
  sliderRep->SetEndCapLength(0.02);

  // Display pixel values (640 X 480)
  // sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToDisplay();
  // sliderRep->GetPoint1Coordinate()->SetValue(128, 48);
  // sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToDisplay();
  // sliderRep->GetPoint2Coordinate()->SetValue(512, 48);
  // Or use this - better because it scales to the window size:
  sliderRep->GetPoint1Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint1Coordinate()->SetValue(0.2, 0.1);
  sliderRep->GetPoint2Coordinate()->SetCoordinateSystemToNormalizedDisplay();
  sliderRep->GetPoint2Coordinate()->SetValue(0.8, 0.1);

  vtkNew<vtkSliderWidget> sliderWidget;
  sliderWidget->SetInteractor(renderWindowInteractor);
  sliderWidget->SetRepresentation(sliderRep);
  sliderWidget->SetAnimationModeToAnimate();
  sliderWidget->EnabledOn();

  vtkNew<vtkSliderCallback> callback;
  callback->SphereSource = sphereSource;

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

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

  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(Slider2D)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  FiltersSources
  InteractionStyle
  InteractionWidgets
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "Slider2D: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(Slider2D MACOSX_BUNDLE Slider2D.cxx )
  target_link_libraries(Slider2D PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS Slider2D
  MODULES ${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

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