--- ray/src/rt/aniso.c	2005/04/19 01:15:06	2.43
+++ ray/src/rt/aniso.c	2010/10/10 22:31:45	2.49
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: aniso.c,v 2.43 2005/04/19 01:15:06 greg Exp $";
+static const char RCSid[] = "$Id: aniso.c,v 2.49 2010/10/10 22:31:45 greg Exp $";
 #endif
 /*
  *  Shading functions for anisotropic materials.
@@ -101,7 +101,7 @@ diraniso(		/* compute source contribution */
 	if (ldot > FTINY && (np->specfl&(SP_REFL|SP_BADU)) == SP_REFL) {
 		/*
 		 *  Compute specular reflection coefficient using
-		 *  anisotropic gaussian distribution model.
+		 *  anisotropic Gaussian distribution model.
 		 */
 						/* add source width if flat */
 		if (np->specfl & SP_FLAT)
@@ -119,14 +119,16 @@ diraniso(		/* compute source contribution */
 		dtmp1 *= dtmp1 / au2;
 		dtmp2 = DOT(np->v, h);
 		dtmp2 *= dtmp2 / av2;
-						/* gaussian */
+						/* new W-G-M-D model */
 		dtmp = DOT(np->pnorm, h);
-		dtmp = (dtmp1 + dtmp2) / (dtmp*dtmp);
-		dtmp = exp(-dtmp) / (4.0*PI * np->pdot * sqrt(au2*av2));
+		dtmp *= dtmp;
+		dtmp1 = (dtmp1 + dtmp2) / dtmp;
+		dtmp = exp(-dtmp1) * DOT(h,h) /
+				(PI * dtmp*dtmp * sqrt(au2*av2));
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->scolor);
-			dtmp *= omega;
+			dtmp *= ldot * omega;
 			scalecolor(ctmp, dtmp);
 			addcolor(cval, ctmp);
 		}
@@ -166,8 +168,8 @@ diraniso(		/* compute source contribution */
 			}
 		} else
 			dtmp = 0.0;
-						/* gaussian */
-		dtmp = exp(-dtmp) / (PI * np->pdot * sqrt(au2*av2));
+						/* Gaussian */
+		dtmp = exp(-dtmp) * (1.0/PI) * sqrt(-ldot/(np->pdot*au2*av2));
 						/* worth using? */
 		if (dtmp > FTINY) {
 			copycolor(ctmp, np->mcolor);
@@ -214,7 +216,7 @@ m_aniso(			/* shade ray that hit something anisotropic
 	nd.specfl = 0;
 	nd.u_alpha = m->oargs.farg[4];
 	nd.v_alpha = m->oargs.farg[5];
-	if (nd.u_alpha < FTINY || nd.v_alpha <= FTINY)
+	if (nd.u_alpha <= FTINY || nd.v_alpha <= FTINY)
 		objerror(m, USER, "roughness too small");
 
 	nd.pdot = raynormal(nd.pnorm, r);	/* perturb normal */
@@ -234,11 +236,9 @@ m_aniso(			/* shade ray that hit something anisotropic
 		if (specthresh >= nd.rspec-FTINY)
 			nd.specfl |= SP_RBLT;
 						/* compute refl. direction */
-		for (i = 0; i < 3; i++)
-			nd.vrefl[i] = r->rdir[i] + 2.0*nd.pdot*nd.pnorm[i];
+		VSUM(nd.vrefl, r->rdir, nd.pnorm, 2.0*nd.pdot);
 		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];
+			VSUM(nd.vrefl, r->rdir, r->ron, 2.0*r->rod);
 	}
 						/* compute transmission */
 	if (m->otype == MAT_TRANS2) {
@@ -339,7 +339,7 @@ getacoords(		/* set up coordinate system */
 
 
 static void
-agaussamp(		/* sample anisotropic gaussian specular */
+agaussamp(		/* sample anisotropic Gaussian specular */
 	RAY  *r,
 	register ANISODAT  *np
 )
@@ -348,14 +348,28 @@ agaussamp(		/* sample anisotropic gaussian specular */
 	FVECT  h;
 	double  rv[2];
 	double  d, sinp, cosp;
-	int  niter;
+	COLOR	scol;
+	int  niter, ns2go;
 	register int  i;
 					/* 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 = 0; niter < MAXITER; niter++) {
-			if (niter)
+		for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
+			if (specjitter > 1.5)
 				d = frandom();
 			else
 				d = urand(ilhash(dimlist,ndims)+samplendx);
@@ -363,10 +377,11 @@ agaussamp(		/* sample anisotropic gaussian specular */
 			d = 2.0*PI * rv[0];
 			cosp = tcos(d) * np->u_alpha;
 			sinp = tsin(d) * np->v_alpha;
-			d = sqrt(cosp*cosp + sinp*sinp);
-			cosp /= d;
-			sinp /= d;
-			rv[1] = 1.0 - specjitter*rv[1];
+			d = 1./sqrt(cosp*cosp + sinp*sinp);
+			cosp *= d;
+			sinp *= d;
+			if ((0. <= specjitter) & (specjitter < 1.))
+				rv[1] = 1.0 - specjitter*rv[1];
 			if (rv[1] <= FTINY)
 				d = 1.0;
 			else
@@ -377,14 +392,22 @@ agaussamp(		/* sample anisotropic gaussian specular */
 				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) {
-				rayvalue(&sr);
-				multcolor(sr.rcol, sr.rcoef);
-				addcolor(r->rcol, sr.rcol);
-				break;
+			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--;
 	}
@@ -393,9 +416,21 @@ agaussamp(		/* sample anisotropic gaussian specular */
 	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 = 0; niter < MAXITER; niter++) {
-			if (niter)
+		for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
+			if (specjitter > 1.5)
 				d = frandom();
 			else
 				d = urand(ilhash(dimlist,ndims)+1823+samplendx);
@@ -403,10 +438,11 @@ agaussamp(		/* sample anisotropic gaussian specular */
 			d = 2.0*PI * rv[0];
 			cosp = tcos(d) * np->u_alpha;
 			sinp = tsin(d) * np->v_alpha;
-			d = sqrt(cosp*cosp + sinp*sinp);
-			cosp /= d;
-			sinp /= d;
-			rv[1] = 1.0 - specjitter*rv[1];
+			d = 1./sqrt(cosp*cosp + sinp*sinp);
+			cosp *= d;
+			sinp *= d;
+			if ((0. <= specjitter) & (specjitter < 1.))
+				rv[1] = 1.0 - specjitter*rv[1];
 			if (rv[1] <= FTINY)
 				d = 1.0;
 			else
@@ -416,13 +452,15 @@ agaussamp(		/* sample anisotropic gaussian specular */
 			for (i = 0; i < 3; i++)
 				sr.rdir[i] = np->prdir[i] +
 						d*(cosp*np->u[i] + sinp*np->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;
-			}
+			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--;
 	}