+##### opengl, glu #####
+website="http://www.mesa3d.org/"
+PKG_CHECK_MODULES([OPENGL], [gl glu],
+ [LIBS="$LIBS $OPENGL_LIBS"
+ CFLAGS="$CFLAGS $OPENGL_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $OPENGL_CFLAGS"],
+ [missing=yes
+ AC_MSG_WARN([Missing OpenGL ($website)])])
+
+##### libpng #####
+website="http://www.libpng.org/pub/png/libpng.html"
+PKG_CHECK_MODULES([PNG], [libpng],
+ [LIBS="$LIBS $PNG_LIBS"
+ CFLAGS="$CFLAGS $PNG_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $PNG_CFLAGS"],
+ [missing=yes
+ AC_MSG_WARN([Missing libpng ($website)])])
+
+##### openal #####
+website="http://connect.creativelabs.com/openal/"
+PKG_CHECK_MODULES([OPENAL], [openal],
+ [LIBS="$LIBS $OPENAL_LIBS"
+ CFLAGS="$CFLAGS $OPENAL_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $OPENAL_CFLAGS"],
+ [missing=yes
+ AC_MSG_WARN([Missing OpenAL ($website)])])