--- ray/src/rt/normal.c	2010/05/07 15:44:52	2.52
+++ ray/src/rt/normal.c	2011/10/26 03:44:56	2.61
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: normal.c,v 2.52 2010/05/07 15:44:52 greg Exp $";
+static const char RCSid[] = "$Id: normal.c,v 2.61 2011/10/26 03:44:56 greg Exp $";
 #endif
 /*
  *  normal.c - shading function for normal materials.
@@ -80,7 +80,7 @@ dirnorm(		/* compute source contribution */
 	register NORMDAT *np = nnp;
 	double  ldot;
 	double  lrdiff, ltdiff;
-	double  dtmp, d2;
+	double  dtmp, d2, d3, d4;
 	FVECT  vtmp;
 	COLOR  ctmp;
 
@@ -115,7 +115,7 @@ dirnorm(		/* compute source contribution */
 	if (ldot > FTINY && (np->specfl&(SP_REFL|SP_PURE)) == SP_REFL) {
 		/*
 		 *  Compute specular reflection coefficient using
-		 *  gaussian distribution model.
+		 *  Gaussian distribution model.
 		 */
 						/* roughness */
 		dtmp = np->alpha2;
@@ -128,13 +128,14 @@ dirnorm(		/* compute source contribution */
 		vtmp[2] = ldir[2] - np->rp->rdir[2];
 		d2 = DOT(vtmp, np->pnorm);
 		d2 *= d2;
-		d2 = (DOT(vtmp,vtmp) - d2) / d2;
-						/* gaussian */
-		dtmp = exp(-d2/dtmp)/(4.*PI * np->pdot * dtmp);
+		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;
+			dtmp *= ldot * omega;
 			scalecolor(ctmp, dtmp);
 			addcolor(cval, ctmp);
 		}
@@ -155,8 +156,8 @@ dirnorm(		/* compute source contribution */
 		 */
 						/* roughness + source */
 		dtmp = np->alpha2 + omega*(1.0/PI);
-						/* gaussian */
-		 dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(PI*dtmp);
+						/* Gaussian */
+		dtmp = exp((2.*DOT(np->prdir,ldir)-2.)/dtmp)/(PI*dtmp);
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->mcolor);
@@ -293,12 +294,11 @@ m_normal(			/* color a ray that hit something normal *
 		if (!(nd.specfl & SP_PURE) && specthresh >= nd.rspec-FTINY)
 			nd.specfl |= SP_RBLT;
 						/* compute reflected ray */
-		for (i = 0; i < 3; i++)
-			nd.vrefl[i] = r->rdir[i] + 2.*nd.pdot*nd.pnorm[i];
+		VSUM(nd.vrefl, r->rdir, nd.pnorm, 2.*nd.pdot);
 						/* penetration? */
 		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];
+			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)) {
@@ -325,10 +325,9 @@ m_normal(			/* color a ray that hit something normal *
 
 	if (nd.rdiff > FTINY) {		/* ambient from this side */
 		copycolor(ctmp, nd.mcolor);	/* modified by material color */
-		if (nd.specfl & SP_RBLT)
-			scalecolor(ctmp, 1.0-nd.trans);
-		else
-			scalecolor(ctmp, nd.rdiff);
+		scalecolor(ctmp, nd.rdiff);
+		if (nd.specfl & SP_RBLT)	/* add in specular as well? */
+			addcolor(ctmp, nd.scolor);
 		multambient(ctmp, r, hastexture ? nd.pnorm : r->ron);
 		addcolor(r->rcol, ctmp);	/* add to returned color */
 	}
@@ -364,7 +363,7 @@ m_normal(			/* color a ray that hit something normal *
 
 
 static void
-gaussamp(			/* sample gaussian specular */
+gaussamp(			/* sample Gaussian specular */
 	RAY  *r,
 	register NORMDAT  *np
 )
@@ -373,7 +372,8 @@ gaussamp(			/* sample gaussian specular */
 	FVECT  u, v, h;
 	double  rv[2];
 	double  d, sinp, cosp;
-	int  niter;
+	COLOR	scol;
+	int  maxiter, ntrials, nstarget, nstaken;
 	register int  i;
 					/* quick test */
 	if ((np->specfl & (SP_REFL|SP_RBLT)) != SP_REFL &&
@@ -391,9 +391,24 @@ gaussamp(			/* sample gaussian specular */
 					/* compute reflection */
 	if ((np->specfl & (SP_REFL|SP_RBLT)) == SP_REFL &&
 			rayorigin(&sr, SPECULAR, r, np->scolor) == 0) {
-		dimlist[ndims++] = (int)np->mp;
-		for (niter = 0; niter < MAXITER; niter++) {
-			if (niter)
+		nstarget = 1;
+		if (specjitter > 1.5) {	/* multiple samples? */
+			nstarget = specjitter*r->rweight + .5;
+			if (sr.rweight <= minweight*nstarget)
+				nstarget = sr.rweight/minweight;
+			if (nstarget > 1) {
+				d = 1./nstarget;
+				scalecolor(sr.rcoef, d);
+				sr.rweight *= d;
+			} else
+				nstarget = 1;
+		}
+		setcolor(scol, 0., 0., 0.);
+		dimlist[ndims++] = (int)(size_t)np->mp;
+		maxiter = MAXITER*nstarget;
+		for (nstaken = ntrials = 0; nstaken < nstarget &&
+						ntrials < maxiter; ntrials++) {
+			if (ntrials)
 				d = frandom();
 			else
 				d = urand(ilhash(dimlist,ndims)+samplendx);
@@ -401,7 +416,8 @@ gaussamp(			/* sample gaussian specular */
 			d = 2.0*PI * rv[0];
 			cosp = tcos(d);
 			sinp = tsin(d);
-			rv[1] = 1.0 - specjitter*rv[1];
+			if ((0. <= specjitter) & (specjitter < 1.))
+				rv[1] = 1.0 - specjitter*rv[1];
 			if (rv[1] <= FTINY)
 				d = 1.0;
 			else
@@ -409,15 +425,30 @@ gaussamp(			/* sample gaussian specular */
 			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) {
+			VSUM(sr.rdir, r->rdir, h, d);
+						/* sample rejection test */
+			if ((d = DOT(sr.rdir, r->ron)) <= FTINY)
+				continue;
+			checknorm(sr.rdir);
+			if (nstarget > 1) {	/* W-G-M-D adjustment */
+				if (nstaken) rayclear(&sr);
 				rayvalue(&sr);
+				d = 2./(1. + r->rod/d);
+				scalecolor(sr.rcol, d);
+				addcolor(scol, sr.rcol);
+			} else {
+				rayvalue(&sr);
 				multcolor(sr.rcol, sr.rcoef);
 				addcolor(r->rcol, sr.rcol);
-				break;
 			}
+			++nstaken;
 		}
+		if (nstarget > 1) {		/* final W-G-M-D weighting */
+			multcolor(scol, sr.rcoef);
+			d = (double)nstarget/ntrials;
+			scalecolor(scol, d);
+			addcolor(r->rcol, scol);
+		}
 		ndims--;
 	}
 					/* compute transmission */
@@ -425,30 +456,48 @@ gaussamp(			/* sample gaussian specular */
 	scalecolor(sr.rcoef, np->tspec);
 	if ((np->specfl & (SP_TRAN|SP_TBLT)) == SP_TRAN &&
 			rayorigin(&sr, SPECULAR, r, sr.rcoef) == 0) {
-		dimlist[ndims++] = (int)np->mp;
-		for (niter = 0; niter < MAXITER; niter++) {
-			if (niter)
+		nstarget = 1;
+		if (specjitter > 1.5) {	/* multiple samples? */
+			nstarget = specjitter*r->rweight + .5;
+			if (sr.rweight <= minweight*nstarget)
+				nstarget = sr.rweight/minweight;
+			if (nstarget > 1) {
+				d = 1./nstarget;
+				scalecolor(sr.rcoef, d);
+				sr.rweight *= d;
+			} else
+				nstarget = 1;
+		}
+		dimlist[ndims++] = (int)(size_t)np->mp;
+		maxiter = MAXITER*nstarget;
+		for (nstaken = ntrials = 0; nstaken < nstarget &&
+						ntrials < maxiter; ntrials++) {
+			if (ntrials)
 				d = frandom();
 			else
-				d = urand(ilhash(dimlist,ndims)+1823+samplendx);
+				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 ((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) {
-				normalize(sr.rdir);	/* OK, normalize */
-				rayvalue(&sr);
-				multcolor(sr.rcol, sr.rcoef);
-				addcolor(r->rcol, sr.rcol);
-				break;
-			}
+						/* sample rejection test */
+			if (DOT(sr.rdir, r->ron) >= -FTINY)
+				continue;
+			normalize(sr.rdir);	/* OK, normalize */
+			if (nstaken)		/* multi-sampling */
+				rayclear(&sr);
+			rayvalue(&sr);
+			multcolor(sr.rcol, sr.rcoef);
+			addcolor(r->rcol, sr.rcol);
+			++nstaken;
 		}
 		ndims--;
 	}