--- ray/src/rt/normal.c	1991/11/12 17:09:11	2.1
+++ ray/src/rt/normal.c	2010/10/10 22:31:46	2.57
@@ -1,9 +1,6 @@
-/* Copyright (c) 1991 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char RCSid[] = "$Id: normal.c,v 2.57 2010/10/10 22:31:46 greg Exp $";
 #endif
-
 /*
  *  normal.c - shading function for normal materials.
  *
@@ -11,17 +8,29 @@ static char SCCSid[] = "$SunId$ LBL";
  *     12/19/85 - added stuff for metals.
  *     6/26/87 - improved specular model.
  *     9/28/87 - added model for translucent materials.
+ *     Later changes described in delta comments.
  */
 
-#include  "ray.h"
+#include "copyright.h"
 
+#include  "ray.h"
+#include  "ambient.h"
+#include  "source.h"
 #include  "otypes.h"
+#include  "rtotypes.h"
+#include  "random.h"
 
+#ifndef  MAXITER
+#define  MAXITER	10		/* maximum # specular ray attempts */
+#endif
+					/* estimate of Fresnel function */
+#define  FRESNE(ci)	(exp(-5.85*(ci)) - 0.00287989916)
+#define  FRESTHRESH	0.017999	/* minimum specularity for approx. */
+
+
 /*
- *	This routine uses portions of the reflection
- *  model described by Cook and Torrance.
- *	The computation of specular components has been simplified by
- *  numerous approximations and ommisions to improve speed.
+ *	This routine implements the isotropic Gaussian
+ *  model described by Ward in Siggraph `92 article.
  *	We orient the surface towards the incoming ray, so a single
  *  surface can be used to represent an infinitely thin object.
  *
@@ -32,17 +41,23 @@ static char SCCSid[] = "$SunId$ LBL";
  *	red 	grn	blu	rspec	rough	trans	tspec
  */
 
-#define  BSPEC(m)	(6.0)		/* specularity parameter b */
+				/* specularity flags */
+#define  SP_REFL	01		/* has reflected specular component */
+#define  SP_TRAN	02		/* has transmitted specular */
+#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 */
 
-extern double  exp();
-
 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 */
 	FVECT  vrefl;		/* vector in direction of reflected ray */
 	FVECT  prdir;		/* vector in transmitted direction */
-	double  alpha2;		/* roughness squared times 2 */
+	double  alpha2;		/* roughness squared */
 	double  rdiff, rspec;	/* reflected specular, diffuse */
 	double  trans;		/* transmissivity */
 	double  tdiff, tspec;	/* transmitted specular, diffuse */
@@ -50,15 +65,23 @@ typedef struct {
 	double  pdot;		/* perturbed dot product */
 }  NORMDAT;		/* normal material data */
 
+static srcdirf_t dirnorm;
+static void gaussamp(RAY  *r, NORMDAT  *np);
 
-dirnorm(cval, np, ldir, omega)		/* compute source contribution */
-COLOR  cval;			/* returned coefficient */
-register NORMDAT  *np;		/* material data */
-FVECT  ldir;			/* light source direction */
-double  omega;			/* light source size */
+
+static void
+dirnorm(		/* compute source contribution */
+	COLOR  cval,			/* returned coefficient */
+	void  *nnp,		/* material data */
+	FVECT  ldir,			/* light source direction */
+	double  omega			/* light source size */
+)
 {
+	register NORMDAT *np = nnp;
 	double  ldot;
-	double  dtmp;
+	double  lrdiff, ltdiff;
+	double  dtmp, d2, d3, d4;
+	FVECT  vtmp;
 	COLOR  ctmp;
 
 	setcolor(cval, 0.0, 0.0, 0.0);
@@ -68,56 +91,77 @@ double  omega;			/* light source size */
 	if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
 		return;		/* wrong side */
 
-	if (ldot > FTINY && np->rdiff > FTINY) {
+				/* Fresnel estimate */
+	lrdiff = np->rdiff;
+	ltdiff = np->tdiff;
+	if (np->specfl & SP_PURE && np->rspec >= FRESTHRESH &&
+			(lrdiff > FTINY) | (ltdiff > FTINY)) {
+		dtmp = 1. - FRESNE(fabs(ldot));
+		lrdiff *= dtmp;
+		ltdiff *= dtmp;
+	}
+
+	if (ldot > FTINY && lrdiff > FTINY) {
 		/*
 		 *  Compute and add diffuse reflected component to returned
 		 *  color.  The diffuse reflected component will always be
 		 *  modified by the color of the material.
 		 */
 		copycolor(ctmp, np->mcolor);
-		dtmp = ldot * omega * np->rdiff / PI;
+		dtmp = ldot * omega * lrdiff * (1.0/PI);
 		scalecolor(ctmp, dtmp);
 		addcolor(cval, ctmp);
 	}
-	if (ldot > FTINY && np->rspec > FTINY && np->alpha2 > FTINY) {
+	if (ldot > FTINY && (np->specfl&(SP_REFL|SP_PURE)) == SP_REFL) {
 		/*
 		 *  Compute specular reflection coefficient using
-		 *  gaussian distribution model.
+		 *  Gaussian distribution model.
 		 */
-						/* roughness + source */
-		dtmp = np->alpha2 + omega/(2.0*PI);
-						/* gaussian */
-		dtmp = exp((DOT(np->vrefl,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
+						/* roughness */
+		dtmp = np->alpha2;
+						/* + source if flat */
+		if (np->specfl & SP_FLAT)
+			dtmp += omega * (0.25/PI);
+						/* half vector */
+		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 *= d2;
+		d3 = DOT(vtmp,vtmp);
+		d4 = (d3 - d2) / d2;
+						/* new W-G-M-D model */
+		dtmp = exp(-d4/dtmp) * d3 / (PI * d2*d2 * dtmp);
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->scolor);
-			dtmp *= omega / np->pdot;
+			dtmp *= ldot * omega;
 			scalecolor(ctmp, dtmp);
 			addcolor(cval, ctmp);
 		}
 	}
-	if (ldot < -FTINY && np->tdiff > FTINY) {
+	if (ldot < -FTINY && ltdiff > FTINY) {
 		/*
 		 *  Compute diffuse transmission.
 		 */
 		copycolor(ctmp, np->mcolor);
-		dtmp = -ldot * omega * np->tdiff / PI;
+		dtmp = -ldot * omega * ltdiff * (1.0/PI);
 		scalecolor(ctmp, dtmp);
 		addcolor(cval, ctmp);
 	}
-	if (ldot < -FTINY && np->tspec > FTINY && np->alpha2 > FTINY) {
+	if (ldot < -FTINY && (np->specfl&(SP_TRAN|SP_PURE)) == SP_TRAN) {
 		/*
 		 *  Compute specular transmission.  Specular transmission
 		 *  is always modified by material color.
 		 */
 						/* roughness + source */
-		dtmp = np->alpha2 + omega/(2.0*PI);
-						/* gaussian */
-		dtmp = exp((DOT(np->prdir,ldir)-1.)/dtmp)/(2.*PI)/dtmp;
+		dtmp = np->alpha2 + omega*(1.0/PI);
+						/* Gaussian */
+		dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(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);
 		}
@@ -125,127 +169,325 @@ double  omega;			/* light source size */
 }
 
 
-m_normal(m, r)			/* color a ray which hit something normal */
-register OBJREC  *m;
-register RAY  *r;
+extern int
+m_normal(			/* color a ray that hit something normal */
+	register OBJREC  *m,
+	register RAY  *r
+)
 {
 	NORMDAT  nd;
+	double  fest;
 	double  transtest, transdist;
-	double  dtmp;
+	double	mirtest, mirdist;
+	int	hastexture;
+	double	d;
 	COLOR  ctmp;
 	register int  i;
-
-	if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
-		objerror(m, USER, "bad # arguments");
 						/* easy shadow test */
 	if (r->crtype & SHADOW && m->otype != MAT_TRANS)
-		return;
+		return(1);
+
+	if (m->oargs.nfargs != (m->otype == MAT_TRANS ? 7 : 5))
+		objerror(m, USER, "bad number of arguments");
+						/* check for back side */
+	if (r->rod < 0.0) {
+		if (!backvis && m->otype != MAT_TRANS) {
+			raytrans(r);
+			return(1);
+		}
+		raytexture(r, m->omod);
+		flipsurface(r);			/* reorient if backvis */
+	} else
+		raytexture(r, m->omod);
 	nd.mp = m;
+	nd.rp = r;
 						/* get material color */
 	setcolor(nd.mcolor, m->oargs.farg[0],
 			   m->oargs.farg[1],
 			   m->oargs.farg[2]);
 						/* get roughness */
+	nd.specfl = 0;
 	nd.alpha2 = m->oargs.farg[4];
-	nd.alpha2 *= 2.0 * nd.alpha2;
-						/* reorient if necessary */
-	if (r->rod < 0.0)
-		flipsurface(r);
-						/* get modifiers */
-	raytexture(r, m->omod);
-	nd.pdot = raynormal(nd.pnorm, r);	/* perturb normal */
+	if ((nd.alpha2 *= nd.alpha2) <= FTINY)
+		nd.specfl |= SP_PURE;
+
+	if ( (hastexture = (DOT(r->pert,r->pert) > FTINY*FTINY)) ) {
+		nd.pdot = raynormal(nd.pnorm, r);	/* perturb normal */
+	} else {
+		VCOPY(nd.pnorm, r->ron);
+		nd.pdot = r->rod;
+	}
+	if (r->ro != NULL && isflat(r->ro->otype))
+		nd.specfl |= SP_FLAT;
 	if (nd.pdot < .001)
 		nd.pdot = .001;			/* non-zero for dirnorm() */
 	multcolor(nd.mcolor, r->pcol);		/* modify material color */
-	transtest = 0;
-						/* get specular component */
+	mirtest = transtest = 0;
+	mirdist = transdist = r->rot;
 	nd.rspec = m->oargs.farg[3];
-
-	if (nd.rspec > FTINY) {			/* has specular component */
-						/* compute specular color */
-		if (m->otype == MAT_METAL)
-			copycolor(nd.scolor, nd.mcolor);
-		else
-			setcolor(nd.scolor, 1.0, 1.0, 1.0);
-		scalecolor(nd.scolor, nd.rspec);
-						/* improved model */
-		dtmp = exp(-BSPEC(m)*nd.pdot);
-		for (i = 0; i < 3; i++)
-			colval(nd.scolor,i) += (1.0-colval(nd.scolor,i))*dtmp;
-		nd.rspec += (1.0-nd.rspec)*dtmp;
-						/* compute reflected ray */
-		for (i = 0; i < 3; i++)
-			nd.vrefl[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i];
-
-		if (nd.alpha2 <= FTINY && !(r->crtype & SHADOW)) {
-			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);
-			}
-		}
-	}
+						/* compute Fresnel approx. */
+	if (nd.specfl & SP_PURE && nd.rspec >= FRESTHRESH) {
+		fest = FRESNE(r->rod);
+		nd.rspec += fest*(1. - nd.rspec);
+	} else
+		fest = 0.;
 						/* compute transmission */
 	if (m->otype == MAT_TRANS) {
 		nd.trans = m->oargs.farg[5]*(1.0 - nd.rspec);
 		nd.tspec = nd.trans * m->oargs.farg[6];
 		nd.tdiff = nd.trans - nd.tspec;
-		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 direction */
-				nd.prdir[i] = r->rdir[i] - .75*r->pert[i];
-			normalize(nd.prdir);
+		if (nd.tspec > FTINY) {
+			nd.specfl |= SP_TRAN;
+							/* check threshold */
+			if (!(nd.specfl & SP_PURE) &&
+					specthresh >= nd.tspec-FTINY)
+				nd.specfl |= SP_TBLT;
+			if (!hastexture || r->crtype & SHADOW) {
+				VCOPY(nd.prdir, r->rdir);
+				transtest = 2;
+			} else {
+				for (i = 0; i < 3; i++)		/* perturb */
+					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
 		nd.tdiff = nd.tspec = nd.trans = 0.0;
 						/* transmitted ray */
-	if (nd.tspec > FTINY && nd.alpha2 <= FTINY) {
+	if ((nd.specfl&(SP_TRAN|SP_PURE|SP_TBLT)) == (SP_TRAN|SP_PURE)) {
 		RAY  lr;
-		if (rayorigin(&lr, r, TRANS, nd.tspec) == 0) {
+		copycolor(lr.rcoef, nd.mcolor);	/* modified by color */
+		scalecolor(lr.rcoef, nd.tspec);
+		if (rayorigin(&lr, TRANS, r, lr.rcoef) == 0) {
 			VCOPY(lr.rdir, nd.prdir);
 			rayvalue(&lr);
-			scalecolor(lr.rcol, nd.tspec);
-			multcolor(lr.rcol, nd.mcolor);	/* modified by color */
+			multcolor(lr.rcol, lr.rcoef);
 			addcolor(r->rcol, lr.rcol);
 			transtest *= bright(lr.rcol);
 			transdist = r->rot + lr.rt;
 		}
+	} else
+		transtest = 0;
+
+	if (r->crtype & SHADOW) {		/* the rest is shadow */
+		r->rt = transdist;
+		return(1);
 	}
-	if (r->crtype & SHADOW)			/* the rest is shadow */
-		return;
+						/* get specular reflection */
+	if (nd.rspec > FTINY) {
+		nd.specfl |= SP_REFL;
+						/* compute specular color */
+		if (m->otype != MAT_METAL) {
+			setcolor(nd.scolor, nd.rspec, nd.rspec, nd.rspec);
+		} else if (fest > FTINY) {
+			d = nd.rspec*(1. - fest);
+			for (i = 0; i < 3; i++)
+				nd.scolor[i] = fest + nd.mcolor[i]*d;
+		} else {
+			copycolor(nd.scolor, nd.mcolor);
+			scalecolor(nd.scolor, nd.rspec);
+		}
+						/* check threshold */
+		if (!(nd.specfl & SP_PURE) && specthresh >= nd.rspec-FTINY)
+			nd.specfl |= SP_RBLT;
+						/* compute reflected ray */
+		VSUM(nd.vrefl, r->rdir, nd.pnorm, 2.*nd.pdot);
+						/* penetration? */
+		if (hastexture && DOT(nd.vrefl, r->ron) <= FTINY)
+			VSUM(nd.vrefl, r->rdir, r->ron, 2.*r->rod);
+		checknorm(nd.vrefl);
+	}
+						/* reflected ray */
+	if ((nd.specfl&(SP_REFL|SP_PURE|SP_RBLT)) == (SP_REFL|SP_PURE)) {
+		RAY  lr;
+		if (rayorigin(&lr, REFLECTED, r, nd.scolor) == 0) {
+			VCOPY(lr.rdir, nd.vrefl);
+			rayvalue(&lr);
+			multcolor(lr.rcol, lr.rcoef);
+			addcolor(r->rcol, lr.rcol);
+			if (!hastexture && nd.specfl & SP_FLAT) {
+				mirtest = 2.*bright(lr.rcol);
+				mirdist = r->rot + lr.rt;
+			}
+		}
+	}
 						/* diffuse reflection */
 	nd.rdiff = 1.0 - nd.trans - nd.rspec;
 
-	if (nd.rdiff <= FTINY && nd.tdiff <= FTINY && nd.alpha2 <= FTINY)
-		return;				/* purely specular */
+	if (nd.specfl & SP_PURE && nd.rdiff <= FTINY && nd.tdiff <= FTINY)
+		return(1);			/* 100% pure specular */
 
+	if (!(nd.specfl & SP_PURE))
+		gaussamp(r, &nd);		/* checks *BLT flags */
+
 	if (nd.rdiff > FTINY) {		/* ambient from this side */
-		ambient(ctmp, r);
-		if (nd.alpha2 <= FTINY)
-			scalecolor(ctmp, nd.rdiff);
-		else
+		copycolor(ctmp, nd.mcolor);	/* modified by material color */
+		if (nd.specfl & SP_RBLT)
 			scalecolor(ctmp, 1.0-nd.trans);
-		multcolor(ctmp, nd.mcolor);	/* modified by material color */
+		else
+			scalecolor(ctmp, nd.rdiff);
+		multambient(ctmp, r, hastexture ? nd.pnorm : r->ron);
 		addcolor(r->rcol, ctmp);	/* add to returned color */
 	}
 	if (nd.tdiff > FTINY) {		/* ambient from other side */
-		flipsurface(r);
-		ambient(ctmp, r);
-		if (nd.alpha2 <= FTINY)
-			scalecolor(ctmp, nd.tdiff);
-		else
+		copycolor(ctmp, nd.mcolor);	/* modified by color */
+		if (nd.specfl & SP_TBLT)
 			scalecolor(ctmp, nd.trans);
-		multcolor(ctmp, nd.mcolor);	/* modified by color */
+		else
+			scalecolor(ctmp, nd.tdiff);
+		flipsurface(r);
+		if (hastexture) {
+			FVECT  bnorm;
+			bnorm[0] = -nd.pnorm[0];
+			bnorm[1] = -nd.pnorm[1];
+			bnorm[2] = -nd.pnorm[2];
+			multambient(ctmp, r, bnorm);
+		} else
+			multambient(ctmp, r, r->ron);
 		addcolor(r->rcol, ctmp);
 		flipsurface(r);
 	}
 					/* add direct component */
 	direct(r, dirnorm, &nd);
 					/* check distance */
-	if (transtest > bright(r->rcol))
+	d = bright(r->rcol);
+	if (transtest > d)
 		r->rt = transdist;
+	else if (mirtest > d)
+		r->rt = mirdist;
+
+	return(1);
+}
+
+
+static void
+gaussamp(			/* sample Gaussian specular */
+	RAY  *r,
+	register NORMDAT  *np
+)
+{
+	RAY  sr;
+	FVECT  u, v, h;
+	double  rv[2];
+	double  d, sinp, cosp;
+	COLOR	scol;
+	int  niter, ns2go;
+	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++)
+		if (np->pnorm[i] < 0.6 && np->pnorm[i] > -0.6)
+			break;
+	v[i] = 1.0;
+	fcross(u, v, np->pnorm);
+	normalize(u);
+	fcross(v, np->pnorm, u);
+					/* compute reflection */
+	if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
+			rayorigin(&sr, SPECULAR, r, np->scolor) == 0) {
+		copycolor(scol, np->scolor);
+		ns2go = 1;
+		if (specjitter > 1.5) {	/* multiple samples? */
+			ns2go = specjitter*r->rweight + .5;
+			if (sr.rweight <= minweight*ns2go)
+				ns2go = sr.rweight/minweight;
+			if (ns2go > 1) {
+				d = 1./ns2go;
+				scalecolor(scol, d);
+				sr.rweight *= d;
+			} else
+				ns2go = 1;
+		}
+		dimlist[ndims++] = (int)np->mp;
+		for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
+			if (specjitter > 1.5)
+				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);
+			if ((0. <= specjitter) & (specjitter < 1.))
+				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);
+			if (d <= np->pdot + FTINY)
+				continue;
+			VSUM(sr.rdir, r->rdir, h, d);
+			if (DOT(sr.rdir, r->ron) <= FTINY)
+				continue;
+			checknorm(sr.rdir);
+			if (specjitter > 1.5) {	/* adjusted W-G-M-D weight */
+				d = 2.*(1. - np->pdot/d);
+				copycolor(sr.rcoef, scol);
+				scalecolor(sr.rcoef, d);
+				rayclear(&sr);
+			}
+			rayvalue(&sr);
+			multcolor(sr.rcol, sr.rcoef);
+			addcolor(r->rcol, sr.rcol);
+			--ns2go;
+		}
+		ndims--;
+	}
+					/* compute transmission */
+	copycolor(sr.rcoef, np->mcolor);	/* modified by color */
+	scalecolor(sr.rcoef, np->tspec);
+	if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN &&
+			rayorigin(&sr, SPECULAR, r, sr.rcoef) == 0) {
+		ns2go = 1;
+		if (specjitter > 1.5) {	/* multiple samples? */
+			ns2go = specjitter*r->rweight + .5;
+			if (sr.rweight <= minweight*ns2go)
+				ns2go = sr.rweight/minweight;
+			if (ns2go > 1) {
+				d = 1./ns2go;
+				scalecolor(sr.rcoef, d);
+				sr.rweight *= d;
+			} else
+				ns2go = 1;
+		}
+		dimlist[ndims++] = (int)np->mp;
+		for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
+			if (specjitter > 1.5)
+				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);
+			if ((0. <= specjitter) & (specjitter < 1.))
+				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)
+				continue;
+			normalize(sr.rdir);	/* OK, normalize */
+			if (specjitter > 1.5)	/* multi-sampling */
+				rayclear(&sr);
+			rayvalue(&sr);
+			multcolor(sr.rcol, sr.rcoef);
+			addcolor(r->rcol, sr.rcol);
+			--ns2go;
+		}
+		ndims--;
+	}
 }