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¶
Danger
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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.