--- ray/src/rt/aniso.c	2010/10/10 19:49:17	2.48
+++ ray/src/rt/aniso.c	2012/07/29 19:01:39	2.54
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char RCSid[] = "$Id: aniso.c,v 2.48 2010/10/10 19:49:17 greg Exp $";
+static const char RCSid[] = "$Id: aniso.c,v 2.54 2012/07/29 19:01:39 greg Exp $";
 #endif
 /*
  *  Shading functions for anisotropic materials.
@@ -21,14 +21,15 @@ static const char RCSid[] = "$Id: aniso.c,v 2.48 2010/
 
 /*
  *	This routine implements the anisotropic Gaussian
- *  model described by Ward in Siggraph `92 article.
+ *  model described by Ward in Siggraph `92 article, updated with
+ *  normalization and sampling adjustments due to Geisler-Moroder and Duer.
  *	We orient the surface towards the incoming ray, so a single
  *  surface can be used to represent an infinitely thin object.
  *
  *  Arguments for MAT_PLASTIC2 and MAT_METAL2 are:
  *  4+ ux	uy	uz	funcfile	[transform...]
  *  0
- *  6  red	grn	blu	specular-frac.	u-facet-slope v-facet-slope
+ *  6  red	grn	blu	specular-frac.	u-rough v-rough
  *
  *  Real arguments for MAT_TRANS2 are:
  *  8  red 	grn	blu	rspec	u-rough	v-rough	trans	tspec
@@ -60,7 +61,6 @@ typedef struct {
 	double  pdot;		/* perturbed dot product */
 }  ANISODAT;		/* anisotropic material data */
 
-static srcdirf_t diraniso;
 static void getacoords(RAY  *r, ANISODAT  *np);
 static void agaussamp(RAY  *r, ANISODAT  *np);
 
@@ -68,12 +68,12 @@ static void agaussamp(RAY  *r, ANISODAT  *np);
 static void
 diraniso(		/* compute source contribution */
 	COLOR  cval,			/* returned coefficient */
-	void  *nnp,		/* material data */
+	void  *nnp,			/* material data */
 	FVECT  ldir,			/* light source direction */
 	double  omega			/* light source size */
 )
 {
-	register ANISODAT *np = nnp;
+	ANISODAT *np = nnp;
 	double  ldot;
 	double  dtmp, dtmp1, dtmp2;
 	FVECT  h;
@@ -87,7 +87,7 @@ diraniso(		/* compute source contribution */
 	if (ldot < 0.0 ? np->trans <= FTINY : np->trans >= 1.0-FTINY)
 		return;		/* wrong side */
 
-	if (ldot > FTINY && np->rdiff > FTINY) {
+	if ((ldot > FTINY) & (np->rdiff > FTINY)) {
 		/*
 		 *  Compute and add diffuse reflected component to returned
 		 *  color.  The diffuse reflected component will always be
@@ -111,9 +111,7 @@ diraniso(		/* compute source contribution */
 		au2 += np->u_alpha*np->u_alpha;
 		av2 += np->v_alpha*np->v_alpha;
 						/* half vector */
-		h[0] = ldir[0] - np->rp->rdir[0];
-		h[1] = ldir[1] - np->rp->rdir[1];
-		h[2] = ldir[2] - np->rp->rdir[2];
+		VSUB(h, ldir, np->rp->rdir);
 						/* ellipse */
 		dtmp1 = DOT(np->u, h);
 		dtmp1 *= dtmp1 / au2;
@@ -133,7 +131,7 @@ diraniso(		/* compute source contribution */
 			addcolor(cval, ctmp);
 		}
 	}
-	if (ldot < -FTINY && np->tdiff > FTINY) {
+	if ((ldot < -FTINY) & (np->tdiff > FTINY)) {
 		/*
 		 *  Compute diffuse transmission.
 		 */
@@ -152,9 +150,7 @@ diraniso(		/* compute source contribution */
 		au2 += np->u_alpha*np->u_alpha;
 		av2 += np->v_alpha*np->v_alpha;
 						/* "half vector" */
-		h[0] = ldir[0] - np->prdir[0];
-		h[1] = ldir[1] - np->prdir[1];
-		h[2] = ldir[2] - np->prdir[2];
+		VSUB(h, ldir, np->prdir);
 		dtmp = DOT(h,h);
 		if (dtmp > FTINY*FTINY) {
 			dtmp1 = DOT(h,np->pnorm);
@@ -181,15 +177,15 @@ diraniso(		/* compute source contribution */
 }
 
 
-extern int
+int
 m_aniso(			/* shade ray that hit something anisotropic */
-	register OBJREC  *m,
-	register RAY  *r
+	OBJREC  *m,
+	RAY  *r
 )
 {
 	ANISODAT  nd;
 	COLOR  ctmp;
-	register int  i;
+	int  i;
 						/* easy shadow test */
 	if (r->crtype & SHADOW)
 		return(1);
@@ -216,7 +212,7 @@ 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 */
@@ -277,10 +273,9 @@ m_aniso(			/* shade ray that hit something anisotropic
 
 	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, nd.pnorm);
 		addcolor(r->rcol, ctmp);	/* add to returned color */
 	}
@@ -310,24 +305,24 @@ m_aniso(			/* shade ray that hit something anisotropic
 static void
 getacoords(		/* set up coordinate system */
 	RAY  *r,
-	register ANISODAT  *np
+	ANISODAT  *np
 )
 {
-	register MFUNC  *mf;
-	register int  i;
+	MFUNC  *mf;
+	int  i;
 
 	mf = getfunc(np->mp, 3, 0x7, 1);
 	setfunc(np->mp, r);
 	errno = 0;
 	for (i = 0; i < 3; i++)
 		np->u[i] = evalue(mf->ep[i]);
-	if (errno == EDOM || errno == ERANGE) {
+	if ((errno == EDOM) | (errno == ERANGE)) {
 		objerror(np->mp, WARNING, "compute error");
 		np->specfl |= SP_BADU;
 		return;
 	}
-	if (mf->f != &unitxf)
-		multv3(np->u, np->u, mf->f->xfm);
+	if (mf->fxp != &unitxf)
+		multv3(np->u, np->u, mf->fxp->xfm);
 	fcross(np->v, np->pnorm, np->u);
 	if (normalize(np->v) == 0.0) {
 		objerror(np->mp, WARNING, "illegal orientation vector");
@@ -341,7 +336,7 @@ getacoords(		/* set up coordinate system */
 static void
 agaussamp(		/* sample anisotropic Gaussian specular */
 	RAY  *r,
-	register ANISODAT  *np
+	ANISODAT  *np
 )
 {
 	RAY  sr;
@@ -349,27 +344,29 @@ agaussamp(		/* sample anisotropic Gaussian specular */
 	double  rv[2];
 	double  d, sinp, cosp;
 	COLOR	scol;
-	int  niter, ns2go;
-	register int  i;
+	int  maxiter, ntrials, nstarget, nstaken;
+	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;
+		nstarget = 1;
 		if (specjitter > 1.5) {	/* multiple samples? */
-			ns2go = specjitter*sr.rweight + .5;
-			if (sr.rweight <= minweight*ns2go)
-				ns2go = sr.rweight/minweight;
-			if (ns2go > 1) {
-				d = 1./ns2go;
-				scalecolor(scol, d);
+			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
-				ns2go = 1;
+				nstarget = 1;
 		}
-		dimlist[ndims++] = (int)np->mp;
-		for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
-			if (specjitter > 1.5)
+		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);
@@ -392,23 +389,30 @@ 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);
-			if (d <= np->pdot + FTINY)
-				continue;
 			VSUM(sr.rdir, r->rdir, h, d);
-			if (DOT(sr.rdir, r->ron) <= FTINY)
+						/* sample rejection test */
+			if ((d = 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);
+			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);
 			}
-			rayvalue(&sr);
-			multcolor(sr.rcol, sr.rcoef);
-			addcolor(r->rcol, sr.rcol);
-			--ns2go;
+			++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 */
@@ -416,21 +420,23 @@ 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;
+		nstarget = 1;
 		if (specjitter > 1.5) {	/* multiple samples? */
-			ns2go = specjitter*sr.rweight + .5;
-			if (sr.rweight <= minweight*ns2go)
-				ns2go = sr.rweight/minweight;
-			if (ns2go > 1) {
-				d = 1./ns2go;
+			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
-				ns2go = 1;
+				nstarget = 1;
 		}
-		dimlist[ndims++] = (int)np->mp;
-		for (niter = ns2go*MAXITER; (ns2go > 0) & (niter > 0); niter--) {
-			if (specjitter > 1.5)
+		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);
@@ -455,12 +461,12 @@ agaussamp(		/* sample anisotropic Gaussian specular */
 			if (DOT(sr.rdir, r->ron) >= -FTINY)
 				continue;
 			normalize(sr.rdir);	/* OK, normalize */
-			if (specjitter > 1.5)	/* multi-sampling */
+			if (nstaken)		/* multi-sampling */
 				rayclear(&sr);
 			rayvalue(&sr);
 			multcolor(sr.rcol, sr.rcoef);
 			addcolor(r->rcol, sr.rcol);
-			--ns2go;
+			++nstaken;
 		}
 		ndims--;
 	}