--- ray/src/rt/normal.c	1995/09/26 15:05:32	2.30
+++ ray/src/rt/normal.c	1998/12/16 18:14:58	2.37
@@ -1,7 +1,7 @@
-/* Copyright (c) 1995 Regents of the University of California */
+/* Copyright (c) 1998 Silicon Graphics, Inc. */
 
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static char SCCSid[] = "$SunId$ SGI";
 #endif
 
 /*
@@ -25,6 +25,10 @@ extern double  specjitter;		/* specular sampling jitte
 
 extern int  backvis;			/* back faces visible? */
 
+#ifndef  MAXITER
+#define  MAXITER	10		/* maximum # specular ray attempts */
+#endif
+
 static  gaussamp();
 
 /*
@@ -228,7 +232,7 @@ register RAY  *r;
 	} else
 		nd.tdiff = nd.tspec = nd.trans = 0.0;
 						/* transmitted ray */
-	if ((nd.specfl&(SP_TRAN|SP_PURE)) == (SP_TRAN|SP_PURE)) {
+	if ((nd.specfl&(SP_TRAN|SP_PURE|SP_TBLT)) == (SP_TRAN|SP_PURE)) {
 		RAY  lr;
 		if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
 			VCOPY(lr.rdir, nd.prdir);
@@ -265,18 +269,18 @@ register RAY  *r;
 		if (hastexture && DOT(nd.vrefl, r->ron) <= FTINY)
 			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;
-			if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) {
-				VCOPY(lr.rdir, nd.vrefl);
-				rayvalue(&lr);
-				multcolor(lr.rcol, nd.scolor);
-				addcolor(r->rcol, lr.rcol);
-				if (!hastexture && nd.specfl & SP_FLAT) {
-					mirtest = 2.*bright(lr.rcol);
-					mirdist = r->rot + lr.rt;
-				}
+	}
+						/* reflected ray */
+	if ((nd.specfl&(SP_REFL|SP_PURE|SP_RBLT)) == (SP_REFL|SP_PURE)) {
+		RAY  lr;
+		if (rayorigin(&lr, r, REFLECTED, nd.rspec) == 0) {
+			VCOPY(lr.rdir, nd.vrefl);
+			rayvalue(&lr);
+			multcolor(lr.rcol, nd.scolor);
+			addcolor(r->rcol, lr.rcol);
+			if (!hastexture && nd.specfl & SP_FLAT) {
+				mirtest = 2.*bright(lr.rcol);
+				mirdist = r->rot + lr.rt;
 			}
 		}
 	}
@@ -286,11 +290,11 @@ register RAY  *r;
 	if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY)
 		return(1);			/* 100% pure specular */
 
-	if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_PURE))
-		gaussamp(r, &nd);
+	if (!(nd.specfl & SP_PURE))
+		gaussamp(r, &nd);		/* checks *BLT flags */
 
 	if (nd.rdiff > FTINY) {		/* ambient from this side */
-		ambient(ctmp, r);
+		ambient(ctmp, r, hastexture?nd.pnorm:r->ron);
 		if (nd.specfl & SP_RBLT)
 			scalecolor(ctmp, 1.0-nd.trans);
 		else
@@ -300,7 +304,14 @@ register RAY  *r;
 	}
 	if (nd.tdiff > FTINY) {		/* ambient from other side */
 		flipsurface(r);
-		ambient(ctmp, r);
+		if (hastexture) {
+			FVECT  bnorm;
+			bnorm[0] = -nd.pnorm[0];
+			bnorm[1] = -nd.pnorm[1];
+			bnorm[2] = -nd.pnorm[2];
+			ambient(ctmp, r, bnorm);
+		} else
+			ambient(ctmp, r, r->ron);
 		if (nd.specfl & SP_TBLT)
 			scalecolor(ctmp, nd.trans);
 		else
@@ -331,6 +342,7 @@ register NORMDAT  *np;
 	FVECT  u, v, h;
 	double  rv[2];
 	double  d, sinp, cosp;
+	int  niter;
 	register int  i;
 					/* quick test */
 	if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL &&
@@ -349,52 +361,63 @@ register NORMDAT  *np;
 	if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
 			rayorigin(&sr, r, SPECULAR, np->rspec) == 0) {
 		dimlist[ndims++] = (int)np->mp;
-		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);
+		for (niter = 0; niter < MAXITER; niter++) {
+			if (niter)
+				d = frandom();
+			else
+				d = urand(ilhash(dimlist,ndims)+samplendx);
+			multisamp(rv, 2, d);
+			d = 2.0*PI * rv[0];
+			cosp = tcos(d);
+			sinp = tsin(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) {
+				rayvalue(&sr);
+				multcolor(sr.rcol, np->scolor);
+				addcolor(r->rcol, sr.rcol);
+				break;
+			}
+		}
 		ndims--;
 	}
 					/* compute transmission */
 	if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN &&
 			rayorigin(&sr, r, SPECULAR, np->tspec) == 0) {
 		dimlist[ndims++] = (int)np->mp;
-		d = urand(ilhash(dimlist,ndims)+1823+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( -log(rv[1]) * np->alpha2 );
-		for (i = 0; i < 3; i++)
-			sr.rdir[i] = np->prdir[i] + d*(cosp*u[i] + sinp*v[i]);
-		if (DOT(sr.rdir, r->ron) < -FTINY)
-			normalize(sr.rdir);		/* OK, normalize */
-		else
-			VCOPY(sr.rdir, np->prdir);	/* else no jitter */
-		rayvalue(&sr);
-		scalecolor(sr.rcol, np->tspec);
-		multcolor(sr.rcol, np->mcolor);		/* modified by color */
-		addcolor(r->rcol, sr.rcol);
+		for (niter = 0; niter < MAXITER; niter++) {
+			if (niter)
+				d = frandom();
+			else
+				d = urand(ilhash(dimlist,ndims)+1823+samplendx);
+			multisamp(rv, 2, d);
+			d = 2.0*PI * rv[0];
+			cosp = tcos(d);
+			sinp = tsin(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++)
+				sr.rdir[i] = np->prdir[i] + d*(cosp*u[i] + sinp*v[i]);
+			if (DOT(sr.rdir, r->ron) < -FTINY) {
+				normalize(sr.rdir);	/* OK, normalize */
+				rayvalue(&sr);
+				scalecolor(sr.rcol, np->tspec);
+				multcolor(sr.rcol, np->mcolor);	/* modified */
+				addcolor(r->rcol, sr.rcol);
+				break;
+			}
+		}
 		ndims--;
 	}
 }