ryzom-core/code/CMakeModules/FindExternal.cmake

# Look for a directory containing external libraries.
#
# The following values are defined
# EXTERNAL_INCLUDE_PATH - where to find external includes
# EXTERNAL_LIBRARY_PATH - where to find external libraries
# EXTERNAL_FOUND        - True if the external libraries are available

# also defined, but not for general use are
IF(EXTERNAL_PATH)
  # in cache already
  SET(EXTERNAL_FIND_QUIETLY TRUE)
ENDIF(EXTERNAL_PATH)

FIND_PATH(EXTERNAL_PATH
  include/png.h
  PATHS
  ${CMAKE_CURRENT_SOURCE_DIR}/3rdParty
  ${CMAKE_CURRENT_SOURCE_DIR}/../3rdParty
  ${CMAKE_CURRENT_SOURCE_DIR}/external
  ${CMAKE_CURRENT_SOURCE_DIR}/../external
)

IF(EXTERNAL_PATH)
  SET(EXTERNAL_FOUND TRUE)
  SET(EXTERNAL_INCLUDE_PATH "${EXTERNAL_PATH}/include")

  IF(NOT CMAKE_SIZEOF_VOID_P)
    MESSAGE(FATAL_ERROR "Size of void* is not set, you should call PROJECT(...) before")
  ENDIF(NOT CMAKE_SIZEOF_VOID_P)

  # Using 32 or 64 bits libraries
  IF(CMAKE_SIZEOF_VOID_P EQUAL 8)
    SET(EXTERNAL_LIBRARY_PATH "${EXTERNAL_PATH}/lib64")
  ELSE(CMAKE_SIZEOF_VOID_P EQUAL 8)
    SET(EXTERNAL_LIBRARY_PATH "${EXTERNAL_PATH}/lib")
  ENDIF(CMAKE_SIZEOF_VOID_P EQUAL 8)

  SET(CMAKE_INCLUDE_PATH "${EXTERNAL_INCLUDE_PATH};${CMAKE_INCLUDE_PATH}")
  # Stupid hack for FindOpenAL.cmake
  SET(CMAKE_INCLUDE_PATH "${EXTERNAL_PATH};${CMAKE_INCLUDE_PATH}")
  SET(CMAKE_LIBRARY_PATH "${EXTERNAL_LIBRARY_PATH};${CMAKE_LIBRARY_PATH}")
ENDIF(EXTERNAL_PATH)

IF(EXTERNAL_FOUND)
  IF(NOT EXTERNAL_FIND_QUIETLY)
    MESSAGE(STATUS "Found external: ${EXTERNAL_PATH}")
  ENDIF(NOT EXTERNAL_FIND_QUIETLY)
ELSE(EXTERNAL_FOUND)
  IF(NOT EXTERNAL_FIND_QUIETLY)
    MESSAGE(STATUS "Warning: Unable to find external!")
  ENDIF(NOT EXTERNAL_FIND_QUIETLY)
ENDIF(EXTERNAL_FOUND)

MARK_AS_ADVANCED(EXTERNAL_INCLUDE_PATH EXTERNAL_LIBRARY_PATH)