--- ray/src/rt/normal.c	1992/01/04 23:36:42	2.3
+++ ray/src/rt/normal.c	1992/05/19 17:09:03	2.20
@@ -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.
@@ -40,11 +43,14 @@ static char SCCSid[] = "$SunId$ LBL";
 				/* specularity flags */
 #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_FLAT	020		/* flat reflecting surface */
+#define  SP_PURE	04		/* purely specular (zero roughness) */
+#define  SP_FLAT	010		/* flat reflecting surface */
+#define  SP_RBLT	020		/* reflection below sample threshold */
+#define  SP_TBLT	040		/* transmission below threshold */
 
 typedef struct {
 	OBJREC  *mp;		/* material pointer */
+	RAY  *rp;		/* ray pointer */
 	short  specfl;		/* specularity flags, defined above */
 	COLOR  mcolor;		/* color of this material */
 	COLOR  scolor;		/* color of specular component */
@@ -66,8 +72,8 @@ FVECT  ldir;			/* light source direction */
 double  omega;			/* light source size */
 {
 	double  ldot;
-	double  dtmp;
-	int	i;
+	double  dtmp, d2;
+	FVECT  vtmp;
 	COLOR  ctmp;
 
 	setcolor(cval, 0.0, 0.0, 0.0);
@@ -94,16 +100,22 @@ double  omega;			/* light source size */
 		 *  gaussian distribution model.
 		 */
 						/* roughness */
-		dtmp = 2.0*np->alpha2;
+		dtmp = np->alpha2;
 						/* + source if flat */
 		if (np->specfl & SP_FLAT)
-			dtmp += omega/(2.0*PI);
+			dtmp += omega/(4.0*PI);
+						/* delta */
+		vtmp[0] = ldir[0] - np->rp->rdir[0];
+		vtmp[1] = ldir[1] - np->rp->rdir[1];
+		vtmp[2] = ldir[2] - np->rp->rdir[2];
+		d2 = DOT(vtmp, np->pnorm);
+		d2 = 2.0 - 2.0*d2/sqrt(DOT(vtmp,vtmp));
 						/* gaussian */
-		dtmp = exp((DOT(np->vrefl,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
+		dtmp = exp(-d2/dtmp)/(4.*PI*dtmp);
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->scolor);
-			dtmp *= omega / np->pdot;
+			dtmp *= omega * sqrt(ldot/np->pdot);
 			scalecolor(ctmp, dtmp);
 			addcolor(cval, ctmp);
 		}
@@ -123,13 +135,13 @@ double  omega;			/* light source size */
 		 *  is always modified by material color.
 		 */
 						/* roughness + source */
-		dtmp = np->alpha2 + omega/(2.0*PI);
+		dtmp = np->alpha2 + omega/PI;
 						/* gaussian */
-		dtmp = exp((DOT(np->prdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
+		dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(4.*PI*dtmp);
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->mcolor);
-			dtmp *= np->tspec * omega / np->pdot;
+			dtmp *= np->tspec * omega * sqrt(-ldot/np->pdot);
 			scalecolor(ctmp, dtmp);
 			addcolor(cval, ctmp);
 		}
@@ -153,6 +165,7 @@ register RAY  *r;
 	if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
 		objerror(m, USER, "bad number of arguments");
 	nd.mp = m;
+	nd.rp = r;
 						/* get material color */
 	setcolor(nd.mcolor, m->oargs.farg[0],
 			   m->oargs.farg[1],
@@ -186,9 +199,18 @@ 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 (!(nd.specfl & SP_PURE) &&
+				specthresh > FTINY &&
+				(specthresh >= 1.-FTINY ||
+				specthresh + .05 - .1*frandom() > 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;
@@ -207,15 +229,22 @@ register RAY  *r;
 		nd.tdiff = nd.trans - nd.tspec;
 		if (nd.tspec > FTINY) {
 			nd.specfl |= SP_TRAN;
+							/* check threshold */
+			if (!(nd.specfl & SP_PURE) && specthresh > FTINY &&
+					(specthresh >= 1.-FTINY ||
+				specthresh + .05 - .1*frandom() > nd.tspec))
+				nd.specfl |= SP_TBLT;
 			if (r->crtype & SHADOW ||
 					DOT(r->pert,r->pert) <= FTINY*FTINY) {
 				VCOPY(nd.prdir, r->rdir);
 				transtest = 2;
 			} else {
 				for (i = 0; i < 3; i++)		/* perturb */
-					nd.prdir[i] = r->rdir[i] -
-							.75*r->pert[i];
-				normalize(nd.prdir);
+					nd.prdir[i] = r->rdir[i] - r->pert[i];
+				if (DOT(nd.prdir, r->ron) < -FTINY)
+					normalize(nd.prdir);	/* OK */
+				else
+					VCOPY(nd.prdir, r->rdir);
 			}
 		}
 	} else
@@ -232,7 +261,8 @@ register RAY  *r;
 			transtest *= bright(lr.rcol);
 			transdist = r->rot + lr.rt;
 		}
-	}
+	} else
+		transtest = 0;
 
 	if (r->crtype & SHADOW)			/* the rest is shadow */
 		return;
@@ -242,7 +272,8 @@ 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)
+	if (r->ro != NULL && (r->ro->otype == OBJ_FACE ||
+			r->ro->otype == OBJ_RING))
 		nd.specfl |= SP_FLAT;
 
 	if (nd.specfl & (SP_REFL|SP_TRAN) && !(nd.specfl & SP_PURE))
@@ -250,14 +281,20 @@ 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);
@@ -279,8 +316,11 @@ register NORMDAT  *np;
 	FVECT  u, v, h;
 	double  rv[2];
 	double  d, sinp, cosp;
-	int  confuse;
 	register int  i;
+					/* quick test */
+	if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL &&
+			(np->specfl & (SP_TRAN|SP_TBLT)) != SP_TRAN)
+		return;
 					/* set up sample coordinates */
 	v[0] = v[1] = v[2] = 0.0;
 	for (i = 0; i < 3; i++)
@@ -291,17 +331,15 @@ 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) {
-		confuse = 0;
 		dimlist[ndims++] = (int)np->mp;
-	refagain:
-		dimlist[ndims] = confuse += 3601;
-		d = urand(ilhash(dimlist,ndims+1)+samplendx);
+		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
@@ -311,12 +349,37 @@ register NORMDAT  *np;
 		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;
+		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 */
+	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);
+		ndims--;
+	}
 }