+if test "x${enable_opengl}" != "xno"; then
+ AX_CHECK_GL
+fi
+if test "x$no_gl" = "xyes" -o "x$enable_opengl" = "xno"; then
+ CXXFLAGS="$CXXFLAGS -DNOOPENGL"
+ enable_opengl="no"
+else
+ CFLAGS="$CFLAGS $GL_CFLAGS"
+ CXXFLAGS="$CXXFLAGS $GL_CFLAGS"
+ LIBS="$LIBS $GL_LIBS"
+fi
+
+AC_CHECK_LIB(z, gzopen,, AC_MSG_ERROR([*** zlib is missing]))
+
+CXXFLAGS="$CXXFLAGS -DDATA_PREFIX='\"$datadir/supertux\"'"