set( WALBERLA_FOUND  OFF                     CACHE  BOOL  "waLBerla found" )
set( WALBERLA_DIR    WALBERLA_DIR-NOTFOUND   CACHE  PATH  "waLBerla path"  )

if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/walberla" )
    # Subdirectory walberla exists
    message( STATUS "Using walberla subfolder" )
    add_subdirectory( walberla EXCLUDE_FROM_ALL )
    waLBerla_import()
    set( WALBERLA_DIR   "${CMAKE_CURRENT_SOURCE_DIR}/walberla" CACHE  PATH  "waLBerla path"  FORCE )
    set( WALBERLA_FOUND ON                                     CACHE  BOOL  "waLBerla found" FORCE )
else()
    # Search for a build directory elsewhere
    find_package( waLBerla REQUIRED NO_MODULE ) 
    message( STATUS "Found waLBerla source directory ${walberla_SOURCE_DIR}" )
    message( STATUS "Found waLBerla binary directory ${walberla_BINARY_DIR}" )
    add_subdirectory( ${walberla_SOURCE_DIR} ${walberla_BINARY_DIR} EXCLUDE_FROM_ALL )
    waLBerla_import()
    set( WALBERLA_DIR   "${walberla_BINARY_DIR}"  CACHE  PATH  "waLBerla path"  FORCE )
    set( WALBERLA_FOUND ON                        CACHE  BOOL  "waLBerla found" FORCE )
endif()