--- ray/src/rt/m_brdf.c	2015/09/02 18:59:01	2.33
+++ ray/src/rt/m_brdf.c	2019/04/19 19:01:32	2.39
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: m_brdf.c,v 2.33 2015/09/02 18:59:01 greg Exp $";
+static const char	RCSid[] = "$Id: m_brdf.c,v 2.39 2019/04/19 19:01:32 greg Exp $";
 #endif
 /*
  *  Shading for materials with arbitrary BRDF's
@@ -209,8 +209,6 @@ m_brdf(			/* color a ray that hit a BRDTfunc material 
 	int  hitfront = 1;
 	BRDFDAT  nd;
 	RAY  sr;
-	double  mirtest=0, mirdist=0;
-	double  transtest=0, transdist=0;
 	int  hasrefl, hastrans;
 	int  hastexture;
 	COLOR  ctmp;
@@ -241,7 +239,7 @@ m_brdf(			/* color a ray that hit a BRDTfunc material 
 			m->oargs.farg[8]);
 						/* get modifiers */
 	raytexture(r, m->omod);
-	hastexture = DOT(r->pert,r->pert) > FTINY*FTINY;
+	hastexture = (DOT(r->pert,r->pert) > FTINY*FTINY);
 	if (hastexture) {			/* perturb normal */
 		nd.pdot = raynormal(nd.pnorm, r);
 	} else {
@@ -259,8 +257,8 @@ m_brdf(			/* color a ray that hit a BRDTfunc material 
 	copycolor(nd.mcolor, r->pcol);		/* get pattern color */
 	multcolor(nd.rdiff, nd.mcolor);		/* modify diffuse values */
 	multcolor(nd.tdiff, nd.mcolor);
-	hasrefl = bright(nd.rdiff) > FTINY;
-	hastrans = bright(nd.tdiff) > FTINY;
+	hasrefl = (bright(nd.rdiff) > FTINY);
+	hastrans = (bright(nd.tdiff) > FTINY);
 						/* load cal file */
 	nd.dp = NULL;
 	mf = getfunc(m, 9, 0x3f, 0);
@@ -273,9 +271,9 @@ m_brdf(			/* color a ray that hit a BRDTfunc material 
 	if ((errno == EDOM) | (errno == ERANGE))
 		objerror(m, WARNING, "compute error");
 	else if (rayorigin(&sr, TRANS, r, ctmp) == 0) {
-		if (!(r->crtype & SHADOW) && hastexture) {
+		if (hastexture && !(r->crtype & (SHADOW|AMBIENT))) {
 						/* perturb direction */
-			VSUM(sr.rdir, r->rdir, r->pert, -.75);
+			VSUB(sr.rdir, r->rdir, r->pert);
 			if (normalize(sr.rdir) == 0.0) {
 				objerror(m, WARNING, "illegal perturbation");
 				VCOPY(sr.rdir, r->rdir);
@@ -286,13 +284,13 @@ m_brdf(			/* color a ray that hit a BRDTfunc material 
 		rayvalue(&sr);
 		multcolor(sr.rcol, sr.rcoef);
 		addcolor(r->rcol, sr.rcol);
-		if (!hastexture) {
-			transtest = 2.0*bright(sr.rcol);
-			transdist = r->rot + sr.rt;
-		}
+		if ((!hastexture || r->crtype & (SHADOW|AMBIENT)) &&
+				nd.tspec > bright(nd.tdiff) + bright(nd.rdiff))
+			r->rxt = r->rot + raydistance(&sr);
 	}
 	if (r->crtype & SHADOW)			/* the rest is shadow */
 		return(1);
+
 						/* compute reflected ray */
 	setbrdfunc(&nd);
 	errno = 0;
@@ -306,11 +304,12 @@ m_brdf(			/* color a ray that hit a BRDTfunc material 
 		checknorm(sr.rdir);
 		rayvalue(&sr);
 		multcolor(sr.rcol, sr.rcoef);
+		copycolor(r->mcol, sr.rcol);
 		addcolor(r->rcol, sr.rcol);
-		if (!hastexture && r->ro != NULL && isflat(r->ro->otype)) {
-			mirtest = 2.0*bright(sr.rcol);
-			mirdist = r->rot + sr.rt;
-		}
+		r->rmt = r->rot;
+		if (r->ro != NULL && isflat(r->ro->otype) &&
+				!hastexture | (r->crtype & AMBIENT))
+			r->rmt += raydistance(&sr);
 	}
 						/* compute ambient */
 	if (hasrefl) {
@@ -337,12 +336,6 @@ m_brdf(			/* color a ray that hit a BRDTfunc material 
 	if (hasrefl | hastrans || m->oargs.sarg[6][0] != '0')
 		direct(r, dirbrdf, &nd);	/* add direct component */
 
-	d = bright(r->rcol);			/* set effective distance */
-	if (transtest > d)
-		r->rt = transdist;
-	else if (mirtest > d)
-		r->rt = mirdist;
-
 	return(1);
 }
 
@@ -416,7 +409,7 @@ m_brdf2(			/* color a ray that hit a BRDF material */
 		multambient(ctmp, r, nd.pnorm);
 		addcolor(r->rcol, ctmp);	/* add to returned color */
 	}
-	if (nd.trans > FTINY) {		/* from other side */
+	if (nd.trans > FTINY) {			/* from other side */
 		flipsurface(r);
 		vtmp[0] = -nd.pnorm[0];
 		vtmp[1] = -nd.pnorm[1];
@@ -445,10 +438,10 @@ setbrdfunc(			/* set up brdf function and variables */
 		return(0);	/* it's OK, setfunc says we're done */
 				/* else (re)assign special variables */
 	multv3(vec, np->pnorm, funcxf.xfm);
-	varset("NxP", '=', vec[0]/funcxf.sca);
-	varset("NyP", '=', vec[1]/funcxf.sca);
-	varset("NzP", '=', vec[2]/funcxf.sca);
-	varset("RdotP", '=', np->pdot <= -1.0 ? -1.0 :
+	varset("NxP`", '=', vec[0]/funcxf.sca);
+	varset("NyP`", '=', vec[1]/funcxf.sca);
+	varset("NzP`", '=', vec[2]/funcxf.sca);
+	varset("RdotP`", '=', np->pdot <= -1.0 ? -1.0 :
 			np->pdot >= 1.0 ? 1.0 : np->pdot);
 	varset("CrP", '=', colval(np->mcolor,RED));
 	varset("CgP", '=', colval(np->mcolor,GRN));