--- ray/src/cv/mgflib/xf.c	1994/07/11 14:47:12	1.6
+++ ray/src/cv/mgflib/xf.c	1994/07/21 14:56:39	1.7
@@ -80,10 +80,14 @@ char	**av;
 					/* translate new specification */
 	if (xf(&thisxf, spec->xac, &xf_argv[spec->xav0]) != spec->xac)
 		return(MG_ETYPE);
+					/* check for vertex reversal */
+	if ((spec->rev = (thisxf.sca < 0.)))
+		thisxf.sca = -thisxf.sca;
 					/* compute total transformation */
 	if (spec->prev != NULL) {
 		multmat4(spec->xf.xfm, thisxf.xfm, spec->prev->xf.xfm);
 		spec->xf.sca = thisxf.sca * spec->prev->xf.sca;
+		spec->rev ^= spec->prev->rev;
 	} else
 		spec->xf = thisxf;
 	spec->xid = comp_xfid(spec->xf.xfm);	/* compute unique ID */