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;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Opacity)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping Opacity: ${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(Opacity MACOSX_BUNDLE Opacity.cxx )
  target_link_libraries(Opacity PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Opacity MACOSX_BUNDLE Opacity.cxx )
  target_link_libraries(Opacity PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Opacity
    MODULES ${VTK_LIBRARIES}
    )
endif () 

cd Opacity/build 

cmake ..

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

make

./Opacity