--- ray/src/common/bsdf_m.c	2011/02/19 23:42:09	3.5
+++ ray/src/common/bsdf_m.c	2011/02/23 21:58:31	3.7
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdf_m.c,v 3.5 2011/02/19 23:42:09 greg Exp $";
+static const char RCSid[] = "$Id: bsdf_m.c,v 3.7 2011/02/23 21:58:31 greg Exp $";
 #endif
 /*
  *  bsdf_m.c
@@ -362,28 +362,31 @@ load_bsdf_data(SDData *sd, ezxml_t wdb, int rowinc)
 	SDSpectralDF	*df;
 	SDMat		*dp;
 	char		*sdata;
+	int		tback;
 	int		inbi, outbi;
 	int		i;
 					/* allocate BSDF component */
 	sdata = ezxml_txt(ezxml_child(wdb, "WavelengthDataDirection"));
-	if (!strcasecmp(sdata, "Transmission Front")) {
+	if ((tback = !strcasecmp(sdata, "Transmission Back")) ||
+			(sd->tf == NULL &&
+				!strcasecmp(sdata, "Transmission Front"))) {
 		if (sd->tf != NULL)
 			SDfreeSpectralDF(sd->tf);
 		if ((sd->tf = SDnewSpectralDF(1)) == NULL)
 			return RC_MEMERR;
 		df = sd->tf;
 	} else if (!strcasecmp(sdata, "Reflection Front")) {
-		if (sd->rf != NULL)
-			SDfreeSpectralDF(sd->rf);
-		if ((sd->rf = SDnewSpectralDF(1)) == NULL)
-			return RC_MEMERR;
-		df = sd->rf;
-	} else if (!strcasecmp(sdata, "Reflection Back")) {
-		if (sd->rb != NULL)
+		if (sd->rb != NULL)	/* note back-front reversal */
 			SDfreeSpectralDF(sd->rb);
 		if ((sd->rb = SDnewSpectralDF(1)) == NULL)
 			return RC_MEMERR;
 		df = sd->rb;
+	} else if (!strcasecmp(sdata, "Reflection Back")) {
+		if (sd->rf != NULL)	/* note front-back reversal */
+			SDfreeSpectralDF(sd->rf);
+		if ((sd->rf = SDnewSpectralDF(1)) == NULL)
+			return RC_MEMERR;
+		df = sd->rf;
 	} else
 		return RC_FAIL;
 	/* XXX should also check "ScatteringDataType" for consistency? */
@@ -421,10 +424,17 @@ load_bsdf_data(SDData *sd, ezxml_t wdb, int rowinc)
 	dp->ib_priv = &abase_list[inbi];
 	dp->ob_priv = &abase_list[outbi];
 	if (df == sd->tf) {
-		dp->ib_vec = &ab_getvecR;
-		dp->ib_ndx = &ab_getndxR;
-		dp->ob_vec = &ab_getvec;
-		dp->ob_ndx = &ab_getndx;
+		if (tback) {
+			dp->ib_vec = &ab_getvecR;
+			dp->ib_ndx = &ab_getndxR;
+			dp->ob_vec = &ab_getvec;
+			dp->ob_ndx = &ab_getndx;
+		} else {
+			dp->ib_vec = &ab_getvec;
+			dp->ib_ndx = &ab_getndx;
+			dp->ob_vec = &ab_getvecR;
+			dp->ob_ndx = &ab_getndxR;
+		}
 	} else if (df == sd->rf) {
 		dp->ib_vec = &ab_getvec;
 		dp->ib_ndx = &ab_getndx;