+if test x$enable_dummy_backend = xyes; then
+ PKG_CHECK_MODULES([UDEV], [libudev], [libudev=yes], [libudev=no])
+fi
+if test x$libudev = xno; then
+ enable_dummy_backend=no
+fi
+AM_CONDITIONAL(BUILD_DUMMY_BACKEND, test x$enable_dummy_backend = xyes)
+
+# Check for OpenGL (X11)
+USE_GLX="no"
+GL_DEPS_CFLAGS=""
+GL_DEPS_LIBS=""
+if test x$enable_glx = xyes; then
+ AC_CHECK_HEADERS([GL/gl.h])
+ AC_CHECK_HEADERS([GL/glx.h])
+ AC_CHECK_LIB(GL, glXCreateContext, [
+ USE_GLX="yes"
+ GL_DEPS_LIBS="-lX11 -lGL"
+ ])
+fi
+AC_SUBST(GL_DEPS_CFLAGS)
+AC_SUBST(GL_DEPS_LIBS)
+AM_CONDITIONAL(USE_GLX, test "$USE_GLX" = "yes")
+