--- ray/src/rt/aniso.c	1994/12/21 09:51:44	2.28
+++ ray/src/rt/aniso.c	1995/11/22 09:27:51	2.31
@@ -263,8 +263,7 @@ register RAY  *r;
 						/* diffuse reflection */
 	nd.rdiff = 1.0 - nd.trans - nd.rspec;
 
-	if (r->ro != NULL && (r->ro->otype == OBJ_FACE ||
-			r->ro->otype == OBJ_RING))
+	if (r->ro != NULL && isflat(r->ro->otype))
 		nd.specfl |= SP_FLAT;
 
 	getacoords(r, &nd);			/* set up coordinates */
@@ -273,7 +272,7 @@ register RAY  *r;
 		agaussamp(r, &nd);
 
 	if (nd.rdiff > FTINY) {		/* ambient from this side */
-		ambient(ctmp, r);
+		ambient(ctmp, r, nd.pnorm);
 		if (nd.specfl & SP_RBLT)
 			scalecolor(ctmp, 1.0-nd.trans);
 		else
@@ -282,8 +281,13 @@ register RAY  *r;
 		addcolor(r->rcol, ctmp);	/* add to returned color */
 	}
 	if (nd.tdiff > FTINY) {		/* ambient from other side */
+		FVECT  bnorm;
+
 		flipsurface(r);
-		ambient(ctmp, r);
+		bnorm[0] = -nd.pnorm[0];
+		bnorm[1] = -nd.pnorm[1];
+		bnorm[2] = -nd.pnorm[2];
+		ambient(ctmp, r, bnorm);
 		if (nd.specfl & SP_TBLT)
 			scalecolor(ctmp, nd.trans);
 		else