--- ray/src/rt/ambient.c	2004/11/05 17:36:55	2.57
+++ ray/src/rt/ambient.c	2005/05/28 22:27:54	2.60
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: ambient.c,v 2.57 2004/11/05 17:36:55 greg Exp $";
+static const char	RCSid[] = "$Id: ambient.c,v 2.60 2005/05/28 22:27:54 greg Exp $";
 #endif
 /*
  *  ambient.c - routines dealing with ambient (inter-reflected) component.
@@ -254,13 +254,14 @@ ambnotify(			/* record new modifier */
 
 
 extern void
-ambient(		/* compute ambient component for ray */
-	COLOR  acol,
+multambient(		/* compute ambient component & multiply by coef. */
+	COLOR  aval,
 	register RAY  *r,
 	FVECT  nrm
 )
 {
 	static int  rdepth = 0;			/* ambient recursion */
+	COLOR	acol;
 	double	d, l;
 
 	if (ambdiv <= 0)			/* no ambient calculation */
@@ -275,10 +276,12 @@ ambient(		/* compute ambient component for ray */
 
 	if (ambacc <= FTINY) {			/* no ambient storage */
 		rdepth++;
-		d = doambient(acol, r, r->rweight, NULL, NULL);
+		d = doambient(acol, r, aval, intens(aval)*r->rweight,
+							NULL, NULL);
 		rdepth--;
 		if (d <= FTINY)
 			goto dumbamb;
+		multcolor(aval, acol);
 		return;
 	}
 
@@ -286,30 +289,35 @@ ambient(		/* compute ambient component for ray */
 		sortambvals(0);
 						/* get ambient value */
 	setcolor(acol, 0.0, 0.0, 0.0);
-	d = sumambient(acol, r, nrm, rdepth,
+	d = sumambient(acol, r, intens(aval)*r->rweight, nrm, rdepth,
 			&atrunk, thescene.cuorg, thescene.cusize);
 	if (d > FTINY) {
 		scalecolor(acol, 1.0/d);
+		multcolor(aval, acol);
 		return;
 	}
 	rdepth++;				/* need to cache new value */
-	d = makeambient(acol, r, nrm, rdepth-1);
+	d = makeambient(acol, r, aval, nrm, rdepth-1);
 	rdepth--;
-	if (d > FTINY)
+	if (d > FTINY) {
+		multcolor(aval, acol);		/* got new value */
 		return;
+	}
 dumbamb:					/* return global value */
-	copycolor(acol, ambval);
-	if ((ambvwt <= 0) | (navsum == 0))
+	if ((ambvwt <= 0) | (navsum == 0)) {
+		multcolor(aval, ambval);
 		return;
+	}
 	l = bright(ambval);			/* average in computations */
 	if (l > FTINY) {
 		d = (log(l)*(double)ambvwt + avsum) /
 				(double)(ambvwt + navsum);
 		d = exp(d) / l;
-		scalecolor(acol, d);		/* apply color of ambval */
+		scalecolor(aval, d);
+		multcolor(aval, ambval);	/* apply color of ambval */
 	} else {
 		d = exp( avsum / (double)navsum );
-		setcolor(acol, d, d, d);	/* neutral color */
+		scalecolor(aval, d);		/* neutral color */
 	}
 }
 
@@ -318,6 +326,7 @@ extern double
 sumambient(	/* get interpolated ambient value */
 	COLOR  acol,
 	register RAY  *r,
+	double  aw,
 	FVECT  rn,
 	int  al,
 	AMBTREE	 *at,
@@ -343,7 +352,7 @@ sumambient(	/* get interpolated ambient value */
 		 */
 		if (av->lvl > al)	/* list sorted, so this works */
 			break;
-		if (av->weight < r->rweight-FTINY)
+		if (av->weight < 0.85*aw)
 			continue;
 		/*
 		 *  Ambient radius test.
@@ -422,28 +431,35 @@ sumambient(	/* get interpolated ambient value */
 				break;
 		}
 		if (j == 3)
-			wsum += sumambient(acol, r, rn, al, at->kid+i, ck0, s);
+			wsum += sumambient(acol, r, aw, rn, al,
+						at->kid+i, ck0, s);
 	}
 	return(wsum);
 }
 
 
 extern double
-makeambient(	/* make a new ambient value */
+makeambient(		/* make a new ambient value */
 	COLOR  acol,
-	register RAY  *r,
+	RAY  *r,
+	COLOR  ac,
 	FVECT  rn,
 	int  al
 )
 {
 	AMBVAL	amb;
+	double	awt;
 	FVECT	gp, gd;
-						/* compute weight */
-	amb.weight = pow(AVGREFL, (double)al);
-	if (r->rweight < 0.1*amb.weight)	/* heuristic */
-		amb.weight = r->rweight;
+	int	i;
+
+	amb.weight = AVGREFL;			/* compute weight */
+	for (i = al; i-- >= 0; )
+		amb.weight *= AVGREFL;
+	awt = intens(ac)*r->rweight;
+	if (awt < 0.07*amb.weight)		/* heuristic override */
+		amb.weight = 1.2*awt;
 						/* compute ambient */
-	amb.rad = doambient(acol, r, amb.weight, gp, gd);
+	amb.rad = doambient(acol, r, ac, amb.weight, gp, gd);
 	if (amb.rad <= FTINY)
 		return(0.0);
 						/* store it */