--- ray/src/rt/ambcomp.c	1991/06/13 09:41:17	1.5
+++ ray/src/rt/ambcomp.c	1991/07/11 16:39:00	1.9
@@ -72,9 +72,9 @@ RAY  *r;
 	hlist[1] = dp->t;
 	hlist[2] = dp->p;
 	hlist[3] = 0;
-	zd = sqrt((dp->t+urand(ilhash(hlist,4)+dp->n))/h->nt);
+	zd = sqrt((dp->t+urand(urind(ilhash(hlist,4),dp->n)))/h->nt);
 	hlist[3] = 1;
-	phi = 2.0*PI * (dp->p+urand(ilhash(hlist,4)+dp->n))/h->np;
+	phi = 2.0*PI * (dp->p+urand(urind(ilhash(hlist,4),dp->n)))/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++) {
@@ -180,20 +180,26 @@ FVECT  pg, dg;
 			addcolor(acol, dp->v);
 		}
 		b = bright(acol);
-		if (b > FTINY)
+		if (b > FTINY) {
 			b = ndivs/b;
-		else
-			b = 0.0;
-		if (pg != NULL) {
-			posgradient(pg, div, &hemi);
-			for (i = 0; i < 3; i++)
-				pg[i] *= 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;
 		}
-		if (dg != NULL) {
-			dirgradient(dg, div, &hemi);
-			for (i = 0; i < 3; i++)
-				dg[i] *= b;
-		}
 		free((char *)div);
 	}
 	b = 1.0/ndivs;
@@ -207,6 +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)
@@ -249,6 +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;