Opacity

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCubeSource.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  // Cube
  vtkNew<vtkCubeSource> cubeSource;
  vtkNew<vtkPolyDataMapper> cubeMapper;
  cubeMapper->SetInputConnection(cubeSource->GetOutputPort());

  vtkNew<vtkActor> cubeActor;
  cubeActor->GetProperty()->SetOpacity(0.5);
  cubeActor->SetMapper(cubeMapper);
  cubeActor->GetProperty()->SetColor(colors->GetColor3d("MistyRose").GetData());

  // Sphere
  vtkNew<vtkSphereSource> sphereSource;
  vtkNew<vtkPolyDataMapper> sphereMapper;
  sphereMapper->SetInputConnection(sphereSource->GetOutputPort());

  vtkNew<vtkActor> sphereActor;
  sphereActor->GetProperty()->SetColor(
      colors->GetColor3d("LightGreen").GetData());
  sphereActor->GetProperty()->SetOpacity(0.7);
  sphereActor->SetMapper(sphereMapper);

  // Create renderers and add actors of plane and cube
  vtkNew<vtkRenderer> renderer;
  renderer->AddActor(cubeActor);
  renderer->AddActor(sphereActor);

  // Add renderer to renderwindow and render
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("Opacity");

  renderer->SetBackground(colors->GetColor3d("DimGray").GetData());
  renderWindow->Render();
  renderer->GetActiveCamera()->Azimuth(-22.5);
  renderer->GetActiveCamera()->Elevation(30);

  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(renderWindow);
  renderWindow->Render();

  interactor->Start();
  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(Opacity)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  FiltersSources
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "Opacity: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
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}
)

cd Opacity/build

cmake ..

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

make

./Opacity