--- ray/src/rt/aniso.c	1992/01/04 23:36:40	2.2
+++ ray/src/rt/aniso.c	1992/01/15 11:02:43	2.5
@@ -16,6 +16,9 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  "random.h"
 
+extern double  specthresh;		/* specular sampling threshold */
+extern double  specjitter;		/* specular sampling jitter */
+
 /*
  *	This anisotropic reflection model uses a variant on the
  *  exponential Gaussian used in normal.c.
@@ -37,8 +40,10 @@ static char SCCSid[] = "$SunId$ LBL";
 #define  SP_REFL	01		/* has reflected specular component */
 #define  SP_TRAN	02		/* has transmitted specular */
 #define  SP_PURE	010		/* purely specular (zero roughness) */
-#define  SP_BADU	020		/* bad u direction calculation */
-#define  SP_FLAT	040		/* reflecting surface is flat */
+#define  SP_FLAT	020		/* reflecting surface is flat */
+#define  SP_RBLT	040		/* reflection below sample threshold */
+#define  SP_TBLT	0100		/* transmission below threshold */
+#define  SP_BADU	0200		/* bad u direction calculation */
 
 typedef struct {
 	OBJREC  *mp;		/* material pointer */
@@ -200,6 +205,12 @@ 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;
 
 		if (!(r->crtype & SHADOW) && nd.specfl & SP_PURE) {
 			RAY  lr;
@@ -220,6 +231,13 @@ 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);
@@ -255,6 +273,9 @@ register RAY  *r;
 	if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY)
 		return;				/* 100% pure specular */
 
+	if (r->ro->otype == OBJ_FACE || r->ro->otype == OBJ_RING)
+		nd.specfl |= SP_FLAT;
+
 	getacoords(r, &nd);			/* set up coordinates */
 
 	if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & (SP_PURE|SP_BADU)))
@@ -262,14 +283,20 @@ 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);
@@ -320,40 +347,42 @@ register ANISODAT  *np;
 	FVECT  h;
 	double  rv[2];
 	double  d, sinp, cosp;
-	int  confuse;
+	int  ntries;
 	register int  i;
 					/* compute reflection */
-	if (np->specfl & SP_REFL &&
+	if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
 			rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
-		confuse = 0;
 		dimlist[ndims++] = (int)np->mp;
-	refagain:
-		dimlist[ndims] = confuse += 3601;
-		d = urand(ilhash(dimlist,ndims+1)+samplendx);
-		multisamp(rv, 2, d);
-		d = 2.0*PI * rv[0];
-		cosp = np->u_alpha * cos(d);
-		sinp = np->v_alpha * sin(d);
-		d = sqrt(cosp*cosp + sinp*sinp);
-		cosp /= d;
-		sinp /= d;
-		if (rv[1] <= FTINY)
-			d = 1.0;
-		else
-			d = sqrt( -log(rv[1]) /
-				(cosp*cosp/(np->u_alpha*np->u_alpha) +
-				 sinp*sinp/(np->v_alpha*np->v_alpha)) );
-		for (i = 0; i < 3; i++)
-			h[i] = np->pnorm[i] +
+		for (ntries = 0; ntries < 10; ntries++) {
+			dimlist[ndims] = ntries * 3601;
+			d = urand(ilhash(dimlist,ndims+1)+samplendx);
+			multisamp(rv, 2, d);
+			d = 2.0*PI * rv[0];
+			cosp = np->u_alpha * cos(d);
+			sinp = np->v_alpha * sin(d);
+			d = sqrt(cosp*cosp + sinp*sinp);
+			cosp /= d;
+			sinp /= d;
+			rv[1] = 1.0 - specjitter*rv[1];
+			if (rv[1] <= FTINY)
+				d = 1.0;
+			else
+				d = sqrt(-log(rv[1]) /
+					(cosp*cosp/(np->u_alpha*np->u_alpha) +
+					 sinp*sinp/(np->v_alpha*np->v_alpha)));
+			for (i = 0; i < 3; i++)
+				h[i] = np->pnorm[i] +
 					d*(cosp*np->u[i] + sinp*np->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)	/* oops! */
-			goto refagain;
-		rayvalue(&sr);
-		multcolor(sr.rcol, np->scolor);
-		addcolor(r->rcol, sr.rcol);
+			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;
+			}
+		}
 		ndims--;
 	}
 					/* compute transmission */