--- ray/src/rt/ambcomp.c	2003/07/21 22:30:19	2.11
+++ ray/src/rt/ambcomp.c	2007/12/31 18:19:42	2.21
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: ambcomp.c,v 2.11 2003/07/21 22:30:19 schorsch Exp $";
+static const char	RCSid[] = "$Id: ambcomp.c,v 2.21 2007/12/31 18:19:42 greg Exp $";
 #endif
 /*
  * Routines to compute "ambient" values using Monte Carlo
@@ -16,35 +16,52 @@ static const char	RCSid[] = "$Id: ambcomp.c,v 2.11 200
 #include  "random.h"
 
 
-static int
-ambcmp(d1, d2)				/* decreasing order */
-AMBSAMP  *d1, *d2;
+void
+inithemi(			/* initialize sampling hemisphere */
+	register AMBHEMI  *hp,
+	COLOR ac,
+	RAY  *r,
+	double  wt
+)
 {
-	if (d1->k < d2->k)
-		return(1);
-	if (d1->k > d2->k)
-		return(-1);
-	return(0);
+	double	d;
+	register int  i;
+					/* set number of divisions */
+	if (ambacc <= FTINY &&
+			wt > (d = 0.8*intens(ac)*r->rweight/(ambdiv*minweight)))
+		wt = d;			/* avoid ray termination */
+	hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
+	i = ambacc > FTINY ? 3 : 1;	/* minimum number of samples */
+	if (hp->nt < i)
+		hp->nt = i;
+	hp->np = PI * hp->nt + 0.5;
+					/* set number of super-samples */
+	hp->ns = ambssamp * wt + 0.5;
+					/* assign coefficient */
+	copycolor(hp->acoef, ac);
+	d = 1.0/(hp->nt*hp->np);
+	scalecolor(hp->acoef, d);
+					/* make axes */
+	VCOPY(hp->uz, r->ron);
+	hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
+	for (i = 0; i < 3; i++)
+		if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
+			break;
+	if (i >= 3)
+		error(CONSISTENCY, "bad ray direction in inithemi");
+	hp->uy[i] = 1.0;
+	fcross(hp->ux, hp->uy, hp->uz);
+	normalize(hp->ux);
+	fcross(hp->uy, hp->uz, hp->ux);
 }
 
 
-static int
-ambnorm(d1, d2)				/* standard order */
-AMBSAMP  *d1, *d2;
-{
-	register int  c;
-
-	if (c = d1->t - d2->t)
-		return(c);
-	return(d1->p - d2->p);
-}
-
-
 int
-divsample(dp, h, r)			/* sample a division */
-register AMBSAMP  *dp;
-AMBHEMI  *h;
-RAY  *r;
+divsample(				/* sample a division */
+	register AMBSAMP  *dp,
+	AMBHEMI  *h,
+	RAY  *r
+)
 {
 	RAY  ar;
 	int  hlist[3];
@@ -53,9 +70,17 @@ RAY  *r;
 	double  b2;
 	double  phi;
 	register int  i;
-
-	if (rayorigin(&ar, r, AMBIENT, AVGREFL) < 0)
+					/* ambient coefficient for weight */
+	if (ambacc > FTINY)
+		setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
+	else
+		copycolor(ar.rcoef, h->acoef);
+	if (rayorigin(&ar, AMBIENT, r, ar.rcoef) < 0)
 		return(-1);
+	if (ambacc > FTINY) {
+		multcolor(ar.rcoef, h->acoef);
+		scalecolor(ar.rcoef, 1./AVGREFL);
+	}
 	hlist[0] = r->rno;
 	hlist[1] = dp->t;
 	hlist[2] = dp->p;
@@ -72,6 +97,7 @@ RAY  *r;
 	dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
 	rayvalue(&ar);
 	ndims--;
+	multcolor(ar.rcol, ar.rcoef);	/* apply coefficient */
 	addcolor(dp->v, ar.rcol);
 					/* use rt to improve gradient calc */
 	if (ar.rt > FTINY && ar.rt < FHUGE)
@@ -87,12 +113,47 @@ RAY  *r;
 }
 
 
+static int
+ambcmp(					/* decreasing order */
+	const void *p1,
+	const void *p2
+)
+{
+	const AMBSAMP	*d1 = (const AMBSAMP *)p1;
+	const AMBSAMP	*d2 = (const AMBSAMP *)p2;
+
+	if (d1->k < d2->k)
+		return(1);
+	if (d1->k > d2->k)
+		return(-1);
+	return(0);
+}
+
+
+static int
+ambnorm(				/* standard order */
+	const void *p1,
+	const void *p2
+)
+{
+	const AMBSAMP	*d1 = (const AMBSAMP *)p1;
+	const AMBSAMP	*d2 = (const AMBSAMP *)p2;
+	register int	c;
+
+	if ( (c = d1->t - d2->t) )
+		return(c);
+	return(d1->p - d2->p);
+}
+
+
 double
-doambient(acol, r, wt, pg, dg)		/* compute ambient component */
-COLOR  acol;
-RAY  *r;
-double  wt;
-FVECT  pg, dg;
+doambient(				/* compute ambient component */
+	COLOR  acol,
+	RAY  *r,
+	double  wt,
+	FVECT  pg,
+	FVECT  dg
+)
 {
 	double  b, d;
 	AMBHEMI  hemi;
@@ -100,19 +161,22 @@ FVECT  pg, dg;
 	AMBSAMP  dnew;
 	register AMBSAMP  *dp;
 	double  arad;
-	int  ndivs, ns;
+	int  divcnt;
 	register int  i, j;
-					/* initialize color */
-	setcolor(acol, 0.0, 0.0, 0.0);
 					/* initialize hemisphere */
-	inithemi(&hemi, r, wt);
-	ndivs = hemi.nt * hemi.np;
-	if (ndivs == 0)
+	inithemi(&hemi, acol, r, wt);
+	divcnt = hemi.nt * hemi.np;
+					/* initialize */
+	if (pg != NULL)
+		pg[0] = pg[1] = pg[2] = 0.0;
+	if (dg != NULL)
+		dg[0] = dg[1] = dg[2] = 0.0;
+	setcolor(acol, 0.0, 0.0, 0.0);
+	if (divcnt == 0)
 		return(0.0);
-					/* set number of super-samples */
-	ns = ambssamp * wt + 0.5;
-	if (ns > 0 || pg != NULL || dg != NULL) {
-		div = (AMBSAMP *)malloc(ndivs*sizeof(AMBSAMP));
+					/* allocate super-samples */
+	if (hemi.ns > 0 || pg != NULL || dg != NULL) {
+		div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
 		if (div == NULL)
 			error(SYSTEM, "out of memory in doambient");
 	} else
@@ -121,33 +185,47 @@ FVECT  pg, dg;
 	arad = 0.0;
 	if ((dp = div) == NULL)
 		dp = &dnew;
+	divcnt = 0;
 	for (i = 0; i < hemi.nt; i++)
 		for (j = 0; j < hemi.np; j++) {
 			dp->t = i; dp->p = j;
 			setcolor(dp->v, 0.0, 0.0, 0.0);
 			dp->r = 0.0;
 			dp->n = 0;
-			if (divsample(dp, &hemi, r) < 0)
-				goto oopsy;
+			if (divsample(dp, &hemi, r) < 0) {
+				if (div != NULL)
+					dp++;
+				continue;
+			}
 			arad += dp->r;
+			divcnt++;
 			if (div != NULL)
 				dp++;
 			else
 				addcolor(acol, dp->v);
 		}
-	if (ns > 0 && arad > FTINY && ndivs/arad < minarad)
-		ns = 0;			/* close enough */
-	else if (ns > 0) {		/* else perform super-sampling */
+	if (!divcnt) {
+		if (div != NULL)
+			free((void *)div);
+		return(0.0);		/* no samples taken */
+	}
+	if (divcnt < hemi.nt*hemi.np) {
+		pg = dg = NULL;		/* incomplete sampling */
+		hemi.ns = 0;
+	} else if (arad > FTINY && divcnt/arad < minarad) {
+		hemi.ns = 0;		/* close enough */
+	} else if (hemi.ns > 0) {	/* else perform super-sampling? */
 		comperrs(div, &hemi);			/* compute errors */
-		qsort(div, ndivs, sizeof(AMBSAMP), ambcmp);	/* sort divs */
+		qsort(div, divcnt, sizeof(AMBSAMP), ambcmp);	/* sort divs */
 						/* super-sample */
-		for (i = ns; i > 0; i--) {
+		for (i = hemi.ns; i > 0; i--) {
 			dnew = *div;
-			if (divsample(&dnew, &hemi, r) < 0)
-				goto oopsy;
-							/* reinsert */
-			dp = div;
-			j = ndivs < i ? ndivs : i;
+			if (divsample(&dnew, &hemi, r) < 0) {
+				dp++;
+				continue;
+			}
+			dp = div;		/* reinsert */
+			j = divcnt < i ? divcnt : i;
 			while (--j > 0 && dnew.k < dp[1].k) {
 				*dp = *(dp+1);
 				dp++;
@@ -155,12 +233,12 @@ FVECT  pg, dg;
 			*dp = dnew;
 		}
 		if (pg != NULL || dg != NULL)	/* restore order */
-			qsort(div, ndivs, sizeof(AMBSAMP), ambnorm);
+			qsort(div, divcnt, sizeof(AMBSAMP), ambnorm);
 	}
 					/* compute returned values */
 	if (div != NULL) {
-		arad = 0.0;
-		for (i = ndivs, dp = div; i-- > 0; dp++) {
+		arad = 0.0;		/* note: divcnt may be < nt*np */
+		for (i = hemi.nt*hemi.np, dp = div; i-- > 0; dp++) {
 			arad += dp->r;
 			if (dp->n > 1) {
 				b = 1.0/dp->n;
@@ -172,7 +250,7 @@ FVECT  pg, dg;
 		}
 		b = bright(acol);
 		if (b > FTINY) {
-			b = ndivs/b;
+			b = 1.0/b;	/* compute & normalize gradient(s) */
 			if (pg != NULL) {
 				posgradient(pg, div, &hemi);
 				for (i = 0; i < 3; i++)
@@ -183,22 +261,13 @@ FVECT  pg, dg;
 				for (i = 0; i < 3; i++)
 					dg[i] *= b;
 			}
-		} else {
-			if (pg != NULL)
-				for (i = 0; i < 3; i++)
-					pg[i] = 0.0;
-			if (dg != NULL)
-				for (i = 0; i < 3; i++)
-					dg[i] = 0.0;
 		}
 		free((void *)div);
 	}
-	b = 1.0/ndivs;
-	scalecolor(acol, b);
 	if (arad <= FTINY)
 		arad = maxarad;
 	else
-		arad = (ndivs+ns)/arad;
+		arad = (divcnt+hemi.ns)/arad;
 	if (pg != NULL) {		/* reduce radius if gradient large */
 		d = DOT(pg,pg);
 		if (d*arad*arad > 1.0)
@@ -215,47 +284,15 @@ FVECT  pg, dg;
 	if ((arad /= sqrt(wt)) > maxarad)
 		arad = maxarad;
 	return(arad);
-oopsy:
-	if (div != NULL)
-		free((void *)div);
-	return(0.0);
 }
 
 
 void
-inithemi(hp, r, wt)		/* initialize sampling hemisphere */
-register AMBHEMI  *hp;
-RAY  *r;
-double  wt;
+comperrs(			/* compute initial error estimates */
+	AMBSAMP  *da,	/* assumes standard ordering */
+	register AMBHEMI  *hp
+)
 {
-	register int  i;
-					/* set number of divisions */
-	if (wt < (.25*PI)/ambdiv+FTINY) {
-		hp->nt = hp->np = 0;
-		return;			/* zero samples */
-	}
-	hp->nt = sqrt(ambdiv * wt / PI) + 0.5;
-	hp->np = PI * hp->nt + 0.5;
-					/* make axes */
-	VCOPY(hp->uz, r->ron);
-	hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
-	for (i = 0; i < 3; i++)
-		if (hp->uz[i] < 0.6 && hp->uz[i] > -0.6)
-			break;
-	if (i >= 3)
-		error(CONSISTENCY, "bad ray direction in inithemi");
-	hp->uy[i] = 1.0;
-	fcross(hp->ux, hp->uy, hp->uz);
-	normalize(hp->ux);
-	fcross(hp->uy, hp->uz, hp->ux);
-}
-
-
-void
-comperrs(da, hp)		/* compute initial error estimates */
-AMBSAMP  *da;		/* assumes standard ordering */
-register AMBHEMI  *hp;
-{
 	double  b, b2;
 	int  i, j;
 	register AMBSAMP  *dp;
@@ -303,10 +340,11 @@ register AMBHEMI  *hp;
 
 
 void
-posgradient(gv, da, hp)				/* compute position gradient */
-FVECT  gv;
-AMBSAMP  *da;			/* assumes standard ordering */
-register AMBHEMI  *hp;
+posgradient(					/* compute position gradient */
+	FVECT  gv,
+	AMBSAMP  *da,			/* assumes standard ordering */
+	register AMBHEMI  *hp
+)
 {
 	register int  i, j;
 	double  nextsine, lastsine, b, d;
@@ -355,15 +393,16 @@ register AMBHEMI  *hp;
 		yd += mag0*sinp + mag1*cosp;
 	}
 	for (i = 0; i < 3; i++)
-		gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])/PI;
+		gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])*(hp->nt*hp->np)/PI;
 }
 
 
 void
-dirgradient(gv, da, hp)				/* compute direction gradient */
-FVECT  gv;
-AMBSAMP  *da;			/* assumes standard ordering */
-register AMBHEMI  *hp;
+dirgradient(					/* compute direction gradient */
+	FVECT  gv,
+	AMBSAMP  *da,			/* assumes standard ordering */
+	register AMBHEMI  *hp
+)
 {
 	register int  i, j;
 	double  mag;
@@ -389,5 +428,5 @@ register AMBHEMI  *hp;
 		yd += mag * tsin(phi);
 	}
 	for (i = 0; i < 3; i++)
-		gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])/(hp->nt*hp->np);
+		gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
 }