ScalarBarActor
VTKExamples/Cxx/Visualization/ScalarBarActor
Description
This example demonstrates how to make a color bar to that reflects the range of values associated with a data set.
Code
ScalarBarActor.cxx
#include <vtkVersion.h>
#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();
#if VTK_MAJOR_VERSION <= 5
mapper->SetInput(poly);
#else
mapper->SetInputData(poly);
#endif
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;
}
CMakeLists.txt
cmake_minimum_required(VERSION 2.8)
PROJECT(ScalarBarActor)
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
add_executable(ScalarBarActor MACOSX_BUNDLE ScalarBarActor.cxx)
target_link_libraries(ScalarBarActor ${VTK_LIBRARIES})
Download and Build ScalarBarActor
Click here to download ScalarBarActor and its CMakeLists.txt file. Once the tarball ScalarBarActor.tar has been downloaded and extracted,
cd ScalarBarActor/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:
./ScalarBarActor
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.