--- ray/src/rt/rcontrib.c	2016/04/27 21:11:32	2.28
+++ ray/src/rt/rcontrib.c	2016/09/12 20:31:34	2.29
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: rcontrib.c,v 2.28 2016/04/27 21:11:32 greg Exp $";
+static const char RCSid[] = "$Id: rcontrib.c,v 2.29 2016/09/12 20:31:34 greg Exp $";
 #endif
 /*
  * Accumulate ray contributions for a set of materials
@@ -135,11 +135,15 @@ addmodifier(char *modn, char *outf, char *prms, char *
 	mp->modname = modn;		/* XXX assumes static string */
 	mp->params = prms;		/* XXX assumes static string */
 	mp->binv = ebinv;
+	mp->bin0 = 0;
 	mp->nbins = bincnt;
 	memset(mp->cbin, 0, sizeof(DCOLOR)*bincnt);
-					/* allocate output streams */
-	for (i = bincnt; i-- > 0; )
-		getostream(mp->outspec, mp->modname, i, 1);
+					/* figure out starting bin */
+	while (!getostream(mp->outspec, mp->modname, mp->bin0, 1))
+		mp->bin0++;
+					/* allocate other output streams */
+	for (i = 0; ++i < mp->nbins; )
+		getostream(mp->outspec, mp->modname, mp->bin0+i, 1);
 	lep->data = (char *)mp;
 	return(mp);
 }