+##### openal #####
+website="http://connect.creativelabs.com/openal/"
+AC_CHECK_HEADERS([AL/al.h AL/alc.h],,
+ [missing=yes
+ echo "***** Missing OpenAL headers ($website) *****"])
+AC_SEARCH_LIBS([alEnable], [openal OpenAL32],,
+ [missing=yes
+ echo "***** Missing libopenal ($website) *****"])
+
+##### libpng #####
+website="http://www.libpng.org/pub/png/libpng.html"
+AC_CHECK_HEADERS([png.h],,
+ [missing=yes
+ echo "***** Missing libpng header ($website) *****"])
+AC_SEARCH_LIBS([png_sig_cmp], [png],,
+ [missing=yes
+ echo "***** Missing libpng ($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) *****"])
+
+if test x$gtk = xyes
+then
+ ##### GTK+ 2.0 #####
+ website="http://www.gtk.org/"
+ PKG_CHECK_MODULES([GTK], [gtk+-2.0],
+ [LIBS="$LIBS $GTK_LIBS"
+ CFLAGS="$CFLAGS $GTK_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $GTK_CFLAGS"],
+ [missing=yes
+ echo "***** Missing GTK+-2.0 ($website) *****"])
+fi