+# Check for "plib" without which we cannot go on
+AC_CHECK_HEADER(plib/ul.h)
+if test "x$ac_cv_header_plib_ul_h" != "xyes"; then
+ echo
+ echo "You *must* have the plib library installed on your system to build"
+ echo "the FGFS simulator!"
+ echo
+ echo "Please see README.plib for more details."
+ echo
+ echo "configure aborted."
+ exit
+fi
+
+AC_MSG_CHECKING([for plib 1.8.4 or newer])
+AC_TRY_RUN([
+#include <plib/ul.h>
+
+#define MIN_PLIB_VERSION 184
+
+int main() {
+ int major, minor, micro;
+
+ if ( PLIB_VERSION < MIN_PLIB_VERSION ) {
+ return -1;
+ }
+
+ return 0;
+}
+
+],
+ AC_MSG_RESULT(yes),
+ [AC_MSG_RESULT(wrong version);
+ AC_MSG_ERROR([Install plib 1.8.4 or later first...])],
+ AC_MSG_RESULT(yes)
+)
+
+dnl If we get here then plib is available, so force use of plib
+dnl joystick lib
+AC_DEFINE([ENABLE_PLIB_JOYSTICK], 1, [Define to enable plib joystick support])
+
+AC_CHECK_HEADER(osg/Version)
+if test "x$ac_cv_header_osg_Version" != "xyes"; then
+ echo
+ echo "You *must* have the OpenSceneGraph support library installed on your system"
+ echo "to build the FGFS simulator!"
+ echo
+ echo "Please see README.OSG for more details."
+ echo
+ echo "configure aborted."
+ exit
+fi
+