--- ray/src/rt/normal.c	1992/01/14 15:33:08	2.4
+++ ray/src/rt/normal.c	1992/01/15 11:41:44	2.7
@@ -20,6 +20,9 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  "random.h"
 
+extern double  specthresh;		/* specular sampling threshold */
+extern double  specjitter;		/* specular sampling jitter */
+
 /*
  *	This routine uses portions of the reflection
  *  model described by Cook and Torrance.
@@ -42,6 +45,8 @@ static char SCCSid[] = "$SunId$ LBL";
 #define  SP_TRAN	02		/* has transmitted specular */
 #define  SP_PURE	010		/* purely specular (zero roughness) */
 #define  SP_FLAT	020		/* flat reflecting surface */
+#define  SP_RBLT	040		/* reflection below sample threshold */
+#define  SP_TBLT	0100		/* transmission below threshold */
 
 typedef struct {
 	OBJREC  *mp;		/* material pointer */
@@ -186,9 +191,18 @@ register RAY  *r;
 		for (i = 0; i < 3; i++)
 			colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp;
 		nd.rspec += (1.0-nd.rspec)*dtmp;
+						/* check threshold */
+		if (specthresh > FTINY &&
+				((specthresh >= 1.-FTINY ||
+				specthresh + (.1 - .2*urand(8199+samplendx))
+					> nd.rspec)))
+			nd.specfl |= SP_RBLT;
 						/* compute reflected ray */
 		for (i = 0; i < 3; i++)
 			nd.vrefl[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i];
+		if (DOT(nd.vrefl, r->ron) <= FTINY)	/* penetration? */
+			for (i = 0; i < 3; i++)		/* safety measure */
+				nd.vrefl[i] = r->rdir[i] + 2.*r->rod*r->ron[i];
 
 		if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) {
 			RAY  lr;
@@ -207,6 +221,13 @@ register RAY  *r;
 		nd.tdiff = nd.trans - nd.tspec;
 		if (nd.tspec > FTINY) {
 			nd.specfl |= SP_TRAN;
+							/* check threshold */
+			if (specthresh > FTINY &&
+					((specthresh >= 1.-FTINY ||
+					specthresh +
+					    (.1 - .2*urand(7241+samplendx))
+						> nd.tspec)))
+				nd.specfl |= SP_TBLT;
 			if (r->crtype & SHADOW ||
 					DOT(r->pert,r->pert) <= FTINY*FTINY) {
 				VCOPY(nd.prdir, r->rdir);
@@ -215,7 +236,10 @@ register RAY  *r;
 				for (i = 0; i < 3; i++)		/* perturb */
 					nd.prdir[i] = r->rdir[i] -
 							.75*r->pert[i];
-				normalize(nd.prdir);
+				if (DOT(nd.prdir, r->ron) < -FTINY)
+					normalize(nd.prdir);	/* OK */
+				else
+					VCOPY(nd.prdir, r->rdir);
 			}
 		}
 	} else
@@ -250,14 +274,20 @@ register RAY  *r;
 
 	if (nd.rdiff > FTINY) {		/* ambient from this side */
 		ambient(ctmp, r);
-		scalecolor(ctmp, nd.rdiff);
+		if (nd.specfl & SP_RBLT)
+			scalecolor(ctmp, 1.0-nd.trans);
+		else
+			scalecolor(ctmp, nd.rdiff);
 		multcolor(ctmp, nd.mcolor);	/* modified by material color */
 		addcolor(r->rcol, ctmp);	/* add to returned color */
 	}
 	if (nd.tdiff > FTINY) {		/* ambient from other side */
 		flipsurface(r);
 		ambient(ctmp, r);
-		scalecolor(ctmp, nd.tdiff);
+		if (nd.specfl & SP_TBLT)
+			scalecolor(ctmp, nd.trans);
+		else
+			scalecolor(ctmp, nd.tdiff);
 		multcolor(ctmp, nd.mcolor);	/* modified by color */
 		addcolor(r->rcol, ctmp);
 		flipsurface(r);
@@ -279,7 +309,6 @@ register NORMDAT  *np;
 	FVECT  u, v, h;
 	double  rv[2];
 	double  d, sinp, cosp;
-	int  ntries;
 	register int  i;
 					/* set up sample coordinates */
 	v[0] = v[1] = v[2] = 0.0;
@@ -291,32 +320,29 @@ register NORMDAT  *np;
 	normalize(u);
 	fcross(v, np->pnorm, u);
 					/* compute reflection */
-	if (np->specfl & SP_REFL &&
+	if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
 			rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
 		dimlist[ndims++] = (int)np->mp;
-		for (ntries = 0; ntries < 10; ntries++) {
-			dimlist[ndims] = ntries * 8912;
-			d = urand(ilhash(dimlist,ndims+1)+samplendx);
-			multisamp(rv, 2, d);
-			d = 2.0*PI * rv[0];
-			cosp = cos(d);
-			sinp = sin(d);
-			if (rv[1] <= FTINY)
-				d = 1.0;
-			else
-				d = sqrt( np->alpha2 * -log(rv[1]) );
-			for (i = 0; i < 3; i++)
-				h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*v[i]);
-			d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
-			for (i = 0; i < 3; i++)
-				sr.rdir[i] = r->rdir[i] + d*h[i];
-			if (DOT(sr.rdir, r->ron) > FTINY) {
-				rayvalue(&sr);
-				multcolor(sr.rcol, np->scolor);
-				addcolor(r->rcol, sr.rcol);
-				break;
-			}
-		}
+		d = urand(ilhash(dimlist,ndims)+samplendx);
+		multisamp(rv, 2, d);
+		d = 2.0*PI * rv[0];
+		cosp = cos(d);
+		sinp = sin(d);
+		rv[1] = 1.0 - specjitter*rv[1];
+		if (rv[1] <= FTINY)
+			d = 1.0;
+		else
+			d = sqrt( np->alpha2 * -log(rv[1]) );
+		for (i = 0; i < 3; i++)
+			h[i] = np->pnorm[i] + d*(cosp*u[i] + sinp*v[i]);
+		d = -2.0 * DOT(h, r->rdir) / (1.0 + d*d);
+		for (i = 0; i < 3; i++)
+			sr.rdir[i] = r->rdir[i] + d*h[i];
+		if (DOT(sr.rdir, r->ron) <= FTINY)
+			VCOPY(sr.rdir, np->vrefl);	/* jitter no good */
+		rayvalue(&sr);
+		multcolor(sr.rcol, np->scolor);
+		addcolor(r->rcol, sr.rcol);
 		ndims--;
 	}
 					/* compute transmission */