--- ray/src/rt/ambcomp.c	1991/06/11 16:37:49	1.4
+++ ray/src/rt/ambcomp.c	1991/08/13 12:16:41	1.11
@@ -60,7 +60,8 @@ AMBHEMI  *h;
 RAY  *r;
 {
 	RAY  ar;
-	int  hlist[4];
+	int  hlist[3];
+	double  spt[2];
 	double  xd, yd, zd;
 	double  b2;
 	double  phi;
@@ -71,10 +72,9 @@ RAY  *r;
 	hlist[0] = r->rno;
 	hlist[1] = dp->t;
 	hlist[2] = dp->p;
-	hlist[3] = 0;
-	zd = sqrt((dp->t+urand(ilhash(hlist,4)+dp->n))/h->nt);
-	hlist[3] = 1;
-	phi = 2.0*PI * (dp->p+urand(ilhash(hlist,4)+dp->n))/h->np;
+	peano(spt, 2, urand(ilhash(hlist,3)+dp->n), .01);
+	zd = sqrt((dp->t + spt[0])/h->nt);
+	phi = 2.0*PI * (dp->p + spt[1])/h->np;
 	xd = cos(phi) * zd;
 	yd = sin(phi) * zd;
 	zd = sqrt(1.0 - zd*zd);
@@ -86,7 +86,7 @@ RAY  *r;
 	rayvalue(&ar);
 	ndims--;
 	addcolor(dp->v, ar.rcol);
-	if (ar.rt < FHUGE)
+	if (ar.rt > FTINY && ar.rt < FHUGE)
 		dp->r += 1.0/ar.rt;
 					/* (re)initialize error */
 	if (dp->n++) {
@@ -179,10 +179,27 @@ FVECT  pg, dg;
 			}
 			addcolor(acol, dp->v);
 		}
-		if (pg != NULL)
-			posgradient(pg, div, &hemi);
-		if (dg != NULL)
-			dirgradient(dg, div, &hemi);
+		b = bright(acol);
+		if (b > FTINY) {
+			b = ndivs/b;
+			if (pg != NULL) {
+				posgradient(pg, div, &hemi);
+				for (i = 0; i < 3; i++)
+					pg[i] *= b;
+			}
+			if (dg != NULL) {
+				dirgradient(dg, div, &hemi);
+				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((char *)div);
 	}
 	b = 1.0/ndivs;
@@ -196,6 +213,14 @@ FVECT  pg, dg;
 	else if (arad < minarad)
 		arad = minarad;
 	arad /= sqrt(r->rweight);
+	if (pg != NULL) {		/* clip pos. gradient if too large */
+		d = 4.0*DOT(pg,pg)*arad*arad;
+		if (d > 1.0) {
+			d = 1.0/sqrt(d);
+			for (i = 0; i < 3; i++)
+				pg[i] *= d;
+		}
+	}
 	return(arad);
 oopsy:
 	if (div != NULL)
@@ -210,8 +235,8 @@ RAY  *r;
 {
 	register int  i;
 					/* set number of divisions */
-	hp->nt = sqrt(ambdiv * r->rweight * 0.5) + 0.5;
-	hp->np = 2 * hp->nt;
+	hp->nt = sqrt(ambdiv * r->rweight / PI) + 0.5;
+	hp->np = PI * hp->nt;
 					/* make axes */
 	VCOPY(hp->uz, r->ron);
 	hp->uy[0] = hp->uy[1] = hp->uy[2] = 0.0;
@@ -238,6 +263,11 @@ register AMBHEMI  *hp;
 	dp = da;
 	for (i = 0; i < hp->nt; i++)
 		for (j = 0; j < hp->np; j++) {
+#ifdef  DEBUG
+			if (dp->t != i || dp->p != j)
+				error(CONSISTENCY,
+					"division order in comperrs");
+#endif
 			b = bright(dp[0].v);
 			if (i > 0) {		/* from above */
 				b2 = bright(dp[-hp->np].v) - b;
@@ -321,7 +351,7 @@ AMBHEMI  *hp;
 		yd += mag0*sinp + mag1*cosp;
 	}
 	for (i = 0; i < 3; i++)
-		gv[i] = xd*hp->ux[i] + yd*hp->uy[i];
+		gv[i] = (xd*hp->ux[i] + yd*hp->uy[i])/PI;
 }
 
 
@@ -353,5 +383,5 @@ AMBHEMI  *hp;
 		yd += mag * sin(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])*PI/(hp->nt*hp->np);
 }