--- ray/src/cv/bsdfinterp.c	2014/02/19 05:16:06	2.17
+++ ray/src/cv/bsdfinterp.c	2014/08/21 10:33:48	2.19
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: bsdfinterp.c,v 2.17 2014/02/19 05:16:06 greg Exp $";
+static const char RCSid[] = "$Id: bsdfinterp.c,v 2.19 2014/08/21 10:33:48 greg Exp $";
 #endif
 /*
  * Interpolate BSDF data from radial basis functions in advection mesh.
@@ -215,13 +215,14 @@ get_interp(MIGRATION *miga[3], FVECT invec)
 		    for (miga[0] = rbf->ejl; miga[0] != NULL;
 					miga[0] = nextedge(rbf,miga[0]))
 			if (opp_rbf(rbf,miga[0]) == rbf->next) {
-				double	nf = 1. - rbf->invec[2]*rbf->invec[2];
+				double	nf = 1. -
+					rbf->next->invec[2]*rbf->next->invec[2];
 				if (nf > FTINY) {	/* rotate to match */
 					nf = sqrt((1.-invec[2]*invec[2])/nf);
-					invec[0] = nf*rbf->invec[0];
-					invec[1] = nf*rbf->invec[1];
+					invec[0] = nf*rbf->next->invec[0];
+					invec[1] = nf*rbf->next->invec[1];
 				}
-				return(0);
+				return(0);	/* rotational symmetry */
 			}
 		    break;
 		}
@@ -262,6 +263,8 @@ get_interp(MIGRATION *miga[3], FVECT invec)
 	}
 }
 
+/* 
+
 /* Advect between recorded incident angles and allocate new RBF */
 RBFNODE *
 advect_rbf(const FVECT invec, int lobe_lim)
@@ -279,7 +282,7 @@ advect_rbf(const FVECT invec, int lobe_lim)
 	VCOPY(sivec, invec);			/* find triangle/edge */
 	sym = get_interp(miga, sivec);
 	if (sym < 0)				/* can't interpolate? */
-		return(NULL);
+		return(def_rbf_spec(invec));
 	if (miga[1] == NULL) {			/* advect along edge? */
 		rbf = e_advect_rbf(miga[0], sivec, lobe_lim);
 		if (single_plane_incident)