--- ray/src/rt/ambcomp.c	2005/06/04 06:10:12	2.17
+++ ray/src/rt/ambcomp.c	2013/02/05 05:40:06	2.23
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: ambcomp.c,v 2.17 2005/06/04 06:10:12 greg Exp $";
+static const char	RCSid[] = "$Id: ambcomp.c,v 2.23 2013/02/05 05:40:06 greg Exp $";
 #endif
 /*
  * Routines to compute "ambient" values using Monte Carlo
@@ -18,17 +18,17 @@ static const char	RCSid[] = "$Id: ambcomp.c,v 2.17 200
 
 void
 inithemi(			/* initialize sampling hemisphere */
-	register AMBHEMI  *hp,
+	AMBHEMI  *hp,
 	COLOR ac,
 	RAY  *r,
 	double  wt
 )
 {
 	double	d;
-	register int  i;
+	int  i;
 					/* set number of divisions */
 	if (ambacc <= FTINY &&
-			wt > (d = 0.8*bright(ac)*r->rweight/(ambdiv*minweight)))
+			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 */
@@ -58,7 +58,7 @@ inithemi(			/* initialize sampling hemisphere */
 
 int
 divsample(				/* sample a division */
-	register AMBSAMP  *dp,
+	AMBSAMP  *dp,
 	AMBHEMI  *h,
 	RAY  *r
 )
@@ -69,7 +69,7 @@ divsample(				/* sample a division */
 	double  xd, yd, zd;
 	double  b2;
 	double  phi;
-	register int  i;
+	int  i;
 					/* ambient coefficient for weight */
 	if (ambacc > FTINY)
 		setcolor(ar.rcoef, AVGREFL, AVGREFL, AVGREFL);
@@ -94,6 +94,7 @@ divsample(				/* sample a division */
 		ar.rdir[i] =	xd*h->ux[i] +
 				yd*h->uy[i] +
 				zd*h->uz[i];
+	checknorm(ar.rdir);
 	dimlist[ndims++] = dp->t*h->np + dp->p + 90171;
 	rayvalue(&ar);
 	ndims--;
@@ -138,7 +139,7 @@ ambnorm(				/* standard order */
 {
 	const AMBSAMP	*d1 = (const AMBSAMP *)p1;
 	const AMBSAMP	*d2 = (const AMBSAMP *)p2;
-	register int	c;
+	int	c;
 
 	if ( (c = d1->t - d2->t) )
 		return(c);
@@ -148,7 +149,7 @@ ambnorm(				/* standard order */
 
 double
 doambient(				/* compute ambient component */
-	COLOR  acol,
+	COLOR  rcol,
 	RAY  *r,
 	double  wt,
 	FVECT  pg,
@@ -159,32 +160,35 @@ doambient(				/* compute ambient component */
 	AMBHEMI  hemi;
 	AMBSAMP  *div;
 	AMBSAMP  dnew;
-	register AMBSAMP  *dp;
+	double  acol[3];
+	AMBSAMP  *dp;
 	double  arad;
-	int  ndivs;
-	register int  i, j;
+	int  divcnt;
+	int  i, j;
 					/* initialize hemisphere */
-	inithemi(&hemi, acol, r, wt);
-	ndivs = hemi.nt * hemi.np;
+	inithemi(&hemi, rcol, 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 (ndivs == 0)
+	setcolor(rcol, 0.0, 0.0, 0.0);
+	if (divcnt == 0)
 		return(0.0);
 					/* allocate super-samples */
 	if (hemi.ns > 0 || pg != NULL || dg != NULL) {
-		div = (AMBSAMP *)malloc(ndivs*sizeof(AMBSAMP));
+		div = (AMBSAMP *)malloc(divcnt*sizeof(AMBSAMP));
 		if (div == NULL)
 			error(SYSTEM, "out of memory in doambient");
 	} else
 		div = NULL;
 					/* sample the divisions */
 	arad = 0.0;
+	acol[0] = acol[1] = acol[2] = 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;
@@ -192,22 +196,30 @@ doambient(				/* compute ambient component */
 			dp->r = 0.0;
 			dp->n = 0;
 			if (divsample(dp, &hemi, r) < 0) {
-				if (div != NULL) dp++;
-				hemi.ns = 0;	/* incomplete sampling */
-				pg = dg = NULL;
+				if (div != NULL)
+					dp++;
 				continue;
 			}
 			arad += dp->r;
+			divcnt++;
 			if (div != NULL)
 				dp++;
 			else
 				addcolor(acol, dp->v);
 		}
-	if (hemi.ns > 0 && arad > FTINY && ndivs/arad < minarad)
+	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 */
+	} 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 = hemi.ns; i > 0; i--) {
 			dnew = *div;
@@ -216,7 +228,7 @@ doambient(				/* compute ambient component */
 				continue;
 			}
 			dp = div;		/* reinsert */
-			j = ndivs < i ? ndivs : i;
+			j = divcnt < i ? divcnt : i;
 			while (--j > 0 && dnew.k < dp[1].k) {
 				*dp = *(dp+1);
 				dp++;
@@ -224,12 +236,12 @@ doambient(				/* compute ambient component */
 			*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;
@@ -255,10 +267,11 @@ doambient(				/* compute ambient component */
 		}
 		free((void *)div);
 	}
+	copycolor(rcol, acol);
 	if (arad <= FTINY)
 		arad = maxarad;
 	else
-		arad = (ndivs+hemi.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)
@@ -281,12 +294,12 @@ doambient(				/* compute ambient component */
 void
 comperrs(			/* compute initial error estimates */
 	AMBSAMP  *da,	/* assumes standard ordering */
-	register AMBHEMI  *hp
+	AMBHEMI  *hp
 )
 {
 	double  b, b2;
 	int  i, j;
-	register AMBSAMP  *dp;
+	AMBSAMP  *dp;
 				/* sum differences from neighbors */
 	dp = da;
 	for (i = 0; i < hp->nt; i++)
@@ -334,14 +347,14 @@ void
 posgradient(					/* compute position gradient */
 	FVECT  gv,
 	AMBSAMP  *da,			/* assumes standard ordering */
-	register AMBHEMI  *hp
+	AMBHEMI  *hp
 )
 {
-	register int  i, j;
+	int  i, j;
 	double  nextsine, lastsine, b, d;
 	double  mag0, mag1;
 	double  phi, cosp, sinp, xd, yd;
-	register AMBSAMP  *dp;
+	AMBSAMP  *dp;
 
 	xd = yd = 0.0;
 	for (j = 0; j < hp->np; j++) {
@@ -392,13 +405,13 @@ void
 dirgradient(					/* compute direction gradient */
 	FVECT  gv,
 	AMBSAMP  *da,			/* assumes standard ordering */
-	register AMBHEMI  *hp
+	AMBHEMI  *hp
 )
 {
-	register int  i, j;
+	int  i, j;
 	double  mag;
 	double  phi, xd, yd;
-	register AMBSAMP  *dp;
+	AMBSAMP  *dp;
 
 	xd = yd = 0.0;
 	for (j = 0; j < hp->np; j++) {