+##### SDL_image #####
+website="http://www.libsdl.org/projects/SDL_image/"
+AC_CHECK_HEADERS([SDL/SDL_image.h],,
+ [missing=yes
+ echo "***** Missing SDL_image header ($website) *****"])
+AC_SEARCH_LIBS([IMG_Load], [SDL_image],,
+ [missing=yes
+ echo "***** Missing libSDL_image ($website) *****"])
+
+##### libvorbis #####
+website="http://www.xiph.org/downloads/"
+AC_CHECK_HEADERS([vorbis/codec.h vorbis/vorbisfile.h],,
+ [missing=yes
+ echo "***** Missing vorbis headers ($website) *****"])
+AC_SEARCH_LIBS([ov_open], [vorbisfile],,
+ [missing=yes
+ echo "***** Missing libvorbisfile ($website) *****"])
+
+##### liblua #####
+website="http://www.lua.org/"
+AC_CHECK_HEADERS([lua.h],,
+ [missing=yes
+ echo "***** Missing lua headers ($website) *****"])
+AC_SEARCH_LIBS([lua_load], [lua],,
+ [missing=yes
+ echo "***** Missing liblua ($website) *****"])
+
+##### librt (optional) #####