Make sky, horizon, flakes and clouds optional, replace repeated strips of skyL/skyR with 2x2 transparent PNGs instead of larger images of variable dimensions, remove a number of empty unused images
file(GLOB lua_src *.c *.h)
set(LIBRARY_OUTPUT_PATH ${EXECUTABLE_OUTPUT_PATH})
IF(APPLE)
set(build_type STATIC)
add_definitions(-DLUA_USE_LINUX)
add_library (lua ${build_type} ${lua_src})
ENDIF(APPLE)
IF(WIN32)
set(build_type SHARED)
add_definitions(-DLUA_BUILD_AS_DLL)
add_library (lua ${build_type} ${lua_src})
SET_TARGET_PROPERTIES(lua PROPERTIES PREFIX "")
install(TARGETS lua RUNTIME DESTINATION ${target_dir})
endif(WIN32)