ScalarBarActor

#include <vtkActor.h>
#include <vtkFloatArray.h>
#include <vtkLookupTable.h>
#include <vtkPointData.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkScalarBarActor.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>

int main (int, char *[])
{
  // Create a sphere for some geometry
  vtkSmartPointer<vtkSphereSource> sphere =
    vtkSmartPointer<vtkSphereSource>::New();
  sphere->SetCenter(0,0,0);
  sphere->SetRadius(1);
  sphere->Update();

  // Create scalar data to associate with the vertices of the sphere
  int numPts = sphere->GetOutput()->GetPoints()->GetNumberOfPoints();
  vtkSmartPointer<vtkFloatArray> scalars =
    vtkSmartPointer<vtkFloatArray>::New();
  scalars->SetNumberOfValues( numPts );
  for( int i = 0; i < numPts; ++i )
  {
    scalars->SetValue(i,static_cast<float>(i)/numPts);
  }
  vtkSmartPointer<vtkPolyData> poly =
    vtkSmartPointer<vtkPolyData>::New();
  poly->DeepCopy(sphere->GetOutput());
  poly->GetPointData()->SetScalars(scalars);

  vtkSmartPointer<vtkPolyDataMapper> mapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputData(poly);
  mapper->ScalarVisibilityOn();
  mapper->SetScalarModeToUsePointData();
  mapper->SetColorModeToMapScalars();

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

  vtkSmartPointer<vtkScalarBarActor> scalarBar =
    vtkSmartPointer<vtkScalarBarActor>::New();
  scalarBar->SetLookupTable(mapper->GetLookupTable());
  scalarBar->SetTitle("Title");
  scalarBar->SetNumberOfLabels(4);

  // Create a lookup table to share between the mapper and the scalarbar
  vtkSmartPointer<vtkLookupTable> hueLut =
    vtkSmartPointer<vtkLookupTable>::New();
  hueLut->SetTableRange (0, 1);
  hueLut->SetHueRange (0, 1);
  hueLut->SetSaturationRange (1, 1);
  hueLut->SetValueRange (1, 1);
  hueLut->Build();

  mapper->SetLookupTable( hueLut );
  scalarBar->SetLookupTable( hueLut );

  // Create a renderer and render window
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();

  renderer->GradientBackgroundOn();
  renderer->SetBackground(1,1,1);
  renderer->SetBackground2(0,0,0);

  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

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

  // Add the actors to the scene
  renderer->AddActor(actor);
  renderer->AddActor2D(scalarBar);

  // Render the scene (lights and cameras are created automatically)
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ScalarBarActor)

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

cd ScalarBarActor/build

cmake ..

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

make

./ScalarBarActor