-AC_CHECK_LIB(SDL_mixer, SDL_OpenAudio, ,AC_MSG_ERROR(SDL_mixer library required))
-AC_CHECK_LIB(SDL_image, IMG_Load, ,AC_MSG_ERROR(SDL_image library required))
-AC_CHECK_LIB(GL, glBegin, ,AC_MSG_ERROR(GL library required))
+AC_CHECK_LIB(SDL_mixer, Mix_OpenAudio,,
+ AC_MSG_ERROR([SDL_mixer library required]))
+
+AC_CHECK_LIB(SDL_image, IMG_Load,,
+ AC_MSG_ERROR([SDL_image library required]))
+
+if test "$enable_opengl" = "yes"; then
+ AX_CHECK_GL
+fi
+if test "$no_gl" = "yes" -o "$enable_opengl" = "no"; then
+ CXXFLAGS="$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]))