ConnectivityFilter

#include <vtkSmartPointer.h>
#include <vtkUnstructuredGrid.h>
#include <vtkSphereSource.h>
#include <vtkConnectivityFilter.h>
#include <vtkDataSetMapper.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkAppendFilter.h>
#include <vtkDelaunay3D.h>

int main(int, char*[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource1 =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource1->Update();

  vtkSmartPointer<vtkDelaunay3D> delaunay1 =
    vtkSmartPointer<vtkDelaunay3D>::New();
  delaunay1->SetInputConnection(sphereSource1->GetOutputPort());
  delaunay1->Update();

  vtkSmartPointer<vtkSphereSource> sphereSource2 =
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource2->SetCenter(5,0,0);
  sphereSource2->Update();

  vtkSmartPointer<vtkDelaunay3D> delaunay2 =
    vtkSmartPointer<vtkDelaunay3D>::New();
  delaunay2->SetInputConnection(sphereSource2->GetOutputPort());
  delaunay2->Update();

  vtkSmartPointer<vtkAppendFilter> appendFilter =
    vtkSmartPointer<vtkAppendFilter>::New();
  appendFilter->AddInputConnection(delaunay1->GetOutputPort());
  appendFilter->AddInputConnection(delaunay2->GetOutputPort());
  appendFilter->Update();

  vtkSmartPointer<vtkConnectivityFilter> connectivityFilter =
    vtkSmartPointer<vtkConnectivityFilter>::New();
  connectivityFilter->SetInputConnection(appendFilter->GetOutputPort());
  connectivityFilter->SetExtractionModeToAllRegions();
  connectivityFilter->ColorRegionsOn();
  connectivityFilter->Update();

  // Visualize
  vtkSmartPointer<vtkDataSetMapper> mapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  mapper->SetInputConnection(connectivityFilter->GetOutputPort());
  mapper->Update();

  vtkSmartPointer<vtkActor> actor =
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(actor);

  vtkSmartPointer<vtkRenderWindow> renwin =
    vtkSmartPointer<vtkRenderWindow>::New();
  renwin->AddRenderer(renderer);
  renwin->Render();

  vtkSmartPointer<vtkRenderWindowInteractor> iren =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow(renwin);
  iren->Initialize();
  iren->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(ConnectivityFilter)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersCore
  vtkFiltersSources
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping ConnectivityFilter: ${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(ConnectivityFilter MACOSX_BUNDLE ConnectivityFilter.cxx )
  target_link_libraries(ConnectivityFilter PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(ConnectivityFilter MACOSX_BUNDLE ConnectivityFilter.cxx )
  target_link_libraries(ConnectivityFilter PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS ConnectivityFilter
    MODULES ${VTK_LIBRARIES}
    )
endif () 

cd ConnectivityFilter/build 

cmake ..

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

make

./ConnectivityFilter