--- ray/src/rt/m_bsdf.c	2011/08/22 16:00:47	2.15
+++ ray/src/rt/m_bsdf.c	2015/05/26 13:21:07	2.28
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: m_bsdf.c,v 2.15 2011/08/22 16:00:47 greg Exp $";
+static const char RCSid[] = "$Id: m_bsdf.c,v 2.28 2015/05/26 13:21:07 greg Exp $";
 #endif
 /*
  *  Shading for materials with BSDFs taken from XML data files
@@ -109,20 +109,22 @@ direct_bsdf_OK(COLOR cval, FVECT ldir, double omega, B
 					/* transform source direction */
 	if (SDmapDir(vsrc, ndp->toloc, ldir) != SDEnone)
 		return(0);
+					/* assign number of samples */
+	ec = SDsizeBSDF(&tomega, ndp->vray, vsrc, SDqueryMin, ndp->sd);
+	if (ec)
+		goto baderror;
 					/* check indirect over-counting */
 	if (ndp->thick != 0 && ndp->pr->crtype & (SPECULAR|AMBIENT)
 				&& vsrc[2] > 0 ^ ndp->vray[2] > 0) {
 		double	dx = vsrc[0] + ndp->vray[0];
 		double	dy = vsrc[1] + ndp->vray[1];
-		if (dx*dx + dy*dy <= omega*(1./PI))
+		if (dx*dx + dy*dy <= omega+tomega)
 			return(0);
 	}
-					/* assign number of samples */
-	ec = SDsizeBSDF(&tomega, ndp->vray, vsrc, SDqueryMin, ndp->sd);
-	if (ec)
-		goto baderror;
 	sf = specjitter * ndp->pr->rweight;
-	if (25.*tomega <= omega)
+	if (tomega <= .0)
+		nsamp = 1;
+	else if (25.*tomega <= omega)
 		nsamp = 100.*sf + .5;
 	else
 		nsamp = 4.*sf*omega/tomega + .5;
@@ -157,6 +159,7 @@ direct_bsdf_OK(COLOR cval, FVECT ldir, double omega, B
 	return(ok);
 baderror:
 	objerror(ndp->mp, USER, transSDError(ec));
+	return(0);			/* gratis return */
 }
 
 /* Compute source contribution for BSDF (reflected & transmitted) */
@@ -379,7 +382,10 @@ sample_sdf(BSDFDAT *ndp, int sflags)
 
 	if (sflags == SDsampSpT) {
 		unsc = ndp->tunsamp;
-		dfp = ndp->sd->tf;
+		if (ndp->pr->rod > 0)
+			dfp = (ndp->sd->tf != NULL) ? ndp->sd->tf : ndp->sd->tb;
+		else
+			dfp = (ndp->sd->tb != NULL) ? ndp->sd->tb : ndp->sd->tf;
 		cvt_sdcolor(unsc, &ndp->sd->tLamb);
 	} else /* sflags == SDsampSpR */ {
 		unsc = ndp->runsamp;
@@ -440,6 +446,7 @@ m_bsdf(OBJREC *m, RAY *r)
 	hitfront = (r->rod > 0);
 						/* load cal file */
 	mf = getfunc(m, 5, 0x1d, 1);
+	setfunc(m, r);
 						/* get thickness */
 	nd.thick = evalue(mf->ep[0]);
 	if ((-FTINY <= nd.thick) & (nd.thick <= FTINY))
@@ -450,6 +457,11 @@ m_bsdf(OBJREC *m, RAY *r)
 			raytrans(r);		/* pass-through */
 		return(1);			/* or shadow */
 	}
+						/* check backface visibility */
+	if (!hitfront & !backvis) {
+		raytrans(r);
+		return(1);
+	}
 						/* check other rays to pass */
 	if (nd.thick != 0 && (!(r->crtype & (SPECULAR|AMBIENT)) ||
 				nd.thick > 0 ^ hitfront)) {
@@ -467,15 +479,9 @@ m_bsdf(OBJREC *m, RAY *r)
 					m->oargs.farg[1],
 					m->oargs.farg[2]);
 	} else {
-		if (m->oargs.nfargs < 6) {	/* check invisible backside */
-			if (!backvis && (nd.sd->rb == NULL) &
-						(nd.sd->tf == NULL)) {
-				SDfreeCache(nd.sd);
-				raytrans(r);
-				return(1);
-			}
+		if (m->oargs.nfargs < 6)
 			setcolor(nd.rdiff, .0, .0, .0);
-		} else
+		else
 			setcolor(nd.rdiff, m->oargs.farg[3],
 					m->oargs.farg[4],
 					m->oargs.farg[5]);
@@ -499,10 +505,14 @@ m_bsdf(OBJREC *m, RAY *r)
 	upvec[1] = evalue(mf->ep[2]);
 	upvec[2] = evalue(mf->ep[3]);
 						/* return to world coords */
-	if (mf->f != &unitxf) {
-		multv3(upvec, upvec, mf->f->xfm);
-		nd.thick *= mf->f->sca;
+	if (mf->fxp != &unitxf) {
+		multv3(upvec, upvec, mf->fxp->xfm);
+		nd.thick *= mf->fxp->sca;
 	}
+	if (r->rox != NULL) {
+		multv3(upvec, upvec, r->rox->f.xfm);
+		nd.thick *= r->rox->f.sca;
+	}
 	raynormal(nd.pnorm, r);
 						/* compute local BSDF xform */
 	ec = SDcompXform(nd.toloc, nd.pnorm, upvec);
@@ -514,15 +524,15 @@ m_bsdf(OBJREC *m, RAY *r)
 	}
 	if (!ec)
 		ec = SDinvXform(nd.fromloc, nd.toloc);
-						/* determine BSDF resolution */
-	if (!ec)
-		ec = SDsizeBSDF(nd.sr_vpsa, nd.vray, NULL,
-						SDqueryMin+SDqueryMax, nd.sd);
 	if (ec) {
-		objerror(m, WARNING, transSDError(ec));
-		SDfreeCache(nd.sd);
+		objerror(m, WARNING, "Illegal orientation vector");
 		return(1);
 	}
+						/* determine BSDF resolution */
+	ec = SDsizeBSDF(nd.sr_vpsa, nd.vray, NULL, SDqueryMin+SDqueryMax, nd.sd);
+	if (ec)
+		objerror(m, USER, transSDError(ec));
+
 	nd.sr_vpsa[0] = sqrt(nd.sr_vpsa[0]);
 	nd.sr_vpsa[1] = sqrt(nd.sr_vpsa[1]);
 	if (!hitfront) {			/* perturb normal towards hit */
@@ -556,7 +566,7 @@ m_bsdf(OBJREC *m, RAY *r)
 		bnorm[2] = -nd.pnorm[2];
 		if (nd.thick != 0) {		/* proxy with offset? */
 			VCOPY(vtmp, r->rop);
-			VSUM(r->rop, vtmp, r->ron, -nd.thick);
+			VSUM(r->rop, vtmp, r->ron, nd.thick);
 			multambient(ctmp, r, bnorm);
 			VCOPY(r->rop, vtmp);
 		} else
@@ -566,7 +576,8 @@ m_bsdf(OBJREC *m, RAY *r)
 			flipsurface(r);
 	}
 						/* add direct component */
-	if ((bright(nd.tdiff) <= FTINY) & (nd.sd->tf == NULL)) {
+	if ((bright(nd.tdiff) <= FTINY) & (nd.sd->tf == NULL) &
+					(nd.sd->tb == NULL)) {
 		direct(r, dir_brdf, &nd);	/* reflection only */
 	} else if (nd.thick == 0) {
 		direct(r, dir_bsdf, &nd);	/* thin surface scattering */