IF(NOT DEFINED GLOBAL_AND_LOCAL_EXTERN_ACGL)
    SET(GLOBAL_AND_LOCAL_EXTERN_ACGL TRUE)

    # Define global and local acgl dependency locations
    IF(NOT DEFINED ACGL_LOCAL_EXTERN_DIR)
        SET(ACGL_LOCAL_EXTERN_DIR "${CMAKE_CURRENT_SOURCE_DIR}/extern")
    ENDIF()

    IF(USE_LOCAL_ACGL)
        FIND_PATH(LOCAL_EXTERN_ACGL_DIR NAMES acgl PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_ACGL_DIR)
            SET(BUILD_ACGL TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_ACGL_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_ANGELSCRIPT)
        FIND_PATH(LOCAL_EXTERN_ANGELSCRIPT_DIR NAMES angelscript PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_ANGELSCRIPT_DIR)
            SET(BUILD_ANGELSCRIPT TRUE)
        ELSE()
            SET(NEED_ANGELSCRIPT_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_ANGELSCRIPT_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_BOX2D)
        FIND_PATH(LOCAL_EXTERN_BOX2D_DIR NAMES box2d PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_BOX2D_DIR)
            SET(BUILD_BOX2D TRUE)
        ELSE()
            SET(NEED_BOX2D_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_BOX2D_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_BULLET)
        FIND_PATH(LOCAL_EXTERN_BULLET_DIR NAMES bullet PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_BULLET_DIR)
            SET(BUILD_BULLET TRUE)
        ELSE()
            SET(NEED_BULLET_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_BULLET_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_FREETYPE)
        FIND_PATH(LOCAL_EXTERN_FREETYPE_DIR NAMES freetype PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_FREETYPE_DIR)
            SET(BUILD_FREETYPE TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_FREETYPE_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_GLEW)
        FIND_PATH(LOCAL_EXTERN_GLEW_DIR NAMES glew PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_GLEW_DIR)
            SET(BUILD_GLEW TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_GLEW_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_GLM)
        FIND_PATH(LOCAL_EXTERN_GLM_DIR NAMES glm PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_GLM_DIR)
            SET(BUILD_GLM TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_GLM_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_GOOGLETEST)
        FIND_PATH(LOCAL_EXTERN_GOOGLETEST_DIR NAMES googletest PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_GOOGLETEST_DIR)
            SET(BUILD_GOOGLETEST TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_GOOGLETEST_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_LUA)
        FIND_PATH(LOCAL_EXTERN_LUA_DIR NAMES lua PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_LUA_DIR)
            SET(BUILD_LUA TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_LUA_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_OGG)
        FIND_PATH(LOCAL_EXTERN_OGG_DIR NAMES ogg PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_OGG_DIR)
            SET(BUILD_OGG TRUE)
        ELSE()
            SET(NEED_OGG_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_OGG_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_OPENAL)
        FIND_PATH(LOCAL_EXTERN_OPENAL_DIR NAMES openal PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_OPENAL_DIR)
            SET(BUILD_OPENAL TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_OPENAL_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_SLB)
        FIND_PATH(LOCAL_EXTERN_SLB_DIR NAMES slb PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_SLB_DIR)
            SET(BUILD_SLB TRUE)
        ELSE()
            SET(NEED_ACGL_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_SLB_DIR CACHE)
    ENDIF()

    IF(USE_LOCAL_VORBIS)
        FIND_PATH(LOCAL_EXTERN_VORBIS_DIR NAMES vorbis PATHS "${ACGL_LOCAL_EXTERN_DIR}" NO_DEFAULT_PATH)
        IF(LOCAL_EXTERN_VORBIS_DIR)
            SET(BUILD_VORBIS TRUE)
        ELSE()
            SET(NEED_VORBIS_GLOBAL_EXTERN_DIR TRUE)
        ENDIF()
        UNSET(LOCAL_EXTERN_VORBIS_DIR CACHE)
    ENDIF()

    IF(NEED_ACGL_GLOBAL_EXTERN_DIR)
        FIND_PATH(ACGL_GLOBAL_EXTERN_DIR NAMES acgl PATHS "${CMAKE_CURRENT_SOURCE_DIR}/../.." "${CMAKE_CURRENT_SOURCE_DIR}/../../SDK" NO_DEFAULT_PATH)
    ELSE()
        UNSET(ACGL_GLOBAL_EXTERN_DIR CACHE)
        UNSET(ACGL_GLOBAL_EXTERN_DIR_FOUND_FIRST_TIME CACHE)
    ENDIF()

    IF(ACGL_GLOBAL_EXTERN_DIR AND NOT DEFINED ACGL_GLOBAL_EXTERN_DIR_FOUND_FIRST_TIME)
        SET(ACGL_GLOBAL_EXTERN_DIR_FOUND_FIRST_TIME TRUE CACHE INTERNAL "")
    ELSEIF(ACGL_GLOBAL_EXTERN_DIR_FOUND_FIRST_TIME)
        SET(ACGL_GLOBAL_EXTERN_DIR_FOUND_FIRST_TIME FALSE CACHE INTERNAL "")
    ENDIF()

    IF(BUILD_ACGL)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/acgl")
    ENDIF()
    IF(BUILD_ANGELSCRIPT)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/angelscript")
    ENDIF()
    IF(BUILD_BOX2D)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/box2d")
    ENDIF()
    IF(BUILD_FREETYPE)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/freetype")
    ENDIF()
    IF(BUILD_BULLET)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/bullet")
    ENDIF()
    IF(BUILD_GLEW)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/glew")
    ENDIF()
    IF(BUILD_GLM)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/glm")
    ENDIF()
    IF(BUILD_GOOGLETEST)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/googletest")
    ENDIF()
    IF(BUILD_LUA)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/lua")
    ENDIF()
    IF(BUILD_OGG)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/ogg")
    ENDIF()
    IF(BUILD_OPENAL)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/openal")
    ENDIF()
    IF(BUILD_SLB)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/slb")
    ENDIF()
    IF(BUILD_VORBIS)
        ADD_SUBDIRECTORY("${ACGL_LOCAL_EXTERN_DIR}/vorbis")
    ENDIF()

ENDIF()