-AC_SEARCH_LIBS([alEnable], [openal openal32],,
- [missing="$missing OpenAL"])
-
-AC_SEARCH_LIBS([alutInit], [alut],,
- [missing="$missing ALUT"])
-
-AC_SEARCH_LIBS([IMG_Load], [SDL_image],,
- [missing="$missing SDL_image"])
-
+##### openal #####
+website="http://connect.creativelabs.com/openal/"
+AC_CHECK_HEADERS([AL/al.h AL/alc.h],,
+ [missing=yes
+ echo "***** Missing OpenAL headers ($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) *****"])