Installed files contain internal ifdefs
The header files are just copied to the installation directory, so all internal ifdefs are still present.
This also means usage of optional features (Voronoi, VTK) is only possible if the corresponding defines are present.
One possible way is to use CMake's configure_file
to replace these instances.
Also to investigate in this case is the possibility to let CMake include all header files resulting in a single one, which is easier to handle.