-if test "$WIN32" = yes; then
- ac_default_prefix="/"
-fi
-AM_CONDITIONAL([WIN32], test "$WIN32" = "yes")
-AM_CONDITIONAL([NOTWIN32], test "$WIN32" = "no")
+AM_CONDITIONAL([SYS_WIN], test "$SYS" = "WIN")
+AM_CONDITIONAL([SYS_MAC], test "$SYS" = "MAC")
+AM_CONDITIONAL([SYS_X11], test "$SYS" = "X11")
+
+# OpenGL flags
+GL_CFLAGS="-DSYS_$SYS"
+case "$SYS" in
+ "WIN") GL_LIBS="-lglu32 -lopengl32" ;;
+ "MAC") GL_LIBS="-framework OpenGL" ;;
+ "X11") GL_LIBS="-lGL -lGLU" ;;
+esac
+AC_SUBST([GL_CFLAGS])
+AC_SUBST([GL_LIBS])
+
+# Check for relative build
+AC_ARG_ENABLE(relative, [AS_HELP_STRING([--enable-relative],
+ [enable runtime search paths @<:@default=no@:>@])],
+ [DOTS=".."; ac_default_prefix="/"])
+AC_SUBST([DOTS])