if(WITH_OPENNURBS)
  if(BUILD_OPENNURBS)
    v4r_clear_vars(OPENNURBS_FOUND)
  endif()
  if(NOT OPENNURBS_FOUND)
    v4r_clear_vars(OPENNURBS_LIBRARY OPENNURBS_INCLUDE_DIRS OPENNURBS_VERSION)
    set(OPENNURBS_LIBRARY opennurbs)
    Set(OPENNURBS_LIBRARIES ${OPENNURBS_LIBRARY})
    add_subdirectory("${V4R_SOURCE_DIR}/3rdparty/opennurbs")
    set(OPENNURBS_INCLUDE_DIRS "${V4R_SOURCE_DIR}/3rdparty")
    set(OPENNURBS_VERSION "1.0") # TODO
  endif()
  set(HAVE_OPENNURBS YES)
endif()
