VTK/Examples/Cxx/Visualization/Opacity

#include <vtkSmartPointer.h>
#include <vtkCubeSource.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkActor.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
 
int main(int, char *[])
{ 
  // Cube
  vtkSmartPointer<vtkCubeSource> cubeSource = 
    vtkSmartPointer<vtkCubeSource>::New();
  vtkSmartPointer<vtkPolyDataMapper> cubeMapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  cubeMapper->SetInputConnection(cubeSource->GetOutputPort());
 
  vtkSmartPointer<vtkActor> cubeActor = 
    vtkSmartPointer<vtkActor>::New();
  cubeActor->GetProperty()->SetOpacity(0.5);
  cubeActor->SetMapper(cubeMapper);
 
  // Sphere
  vtkSmartPointer<vtkSphereSource> sphereSource = 
    vtkSmartPointer<vtkSphereSource>::New();
  vtkSmartPointer<vtkPolyDataMapper> sphereMapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  sphereMapper->SetInputConnection(sphereSource->GetOutputPort());
 
  vtkSmartPointer<vtkActor> sphereActor = 
    vtkSmartPointer<vtkActor>::New();
  sphereActor->GetProperty()->SetColor(0.5,1,0.5);
  sphereActor->GetProperty()->SetOpacity(0.5);
  sphereActor->SetMapper(sphereMapper);
 
  // Create renderers and add actors of plane and cube
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(cubeActor);
  renderer->AddActor(sphereActor);
 
  // Add renderer to renderwindow and render
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
 
  vtkSmartPointer<vtkRenderWindowInteractor> interactor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);
  renderer->SetBackground(0,0,0);
  renderWindow->Render();
 
  interactor->Start();
  return EXIT_SUCCESS;
}