--- ray/src/rt/ambient.c	1995/04/29 10:51:28	2.27
+++ ray/src/rt/ambient.c	1995/10/17 18:22:47	2.32
@@ -18,7 +18,12 @@ static char SCCSid[] = "$SunId$ LBL";
 
 #include  "random.h"
 
-#define	 OCTSCALE	0.5	/* ceil((valid rad.)/(cube size)) */
+#ifndef  OCTSCALE
+#define	 OCTSCALE	1.0	/* ceil((valid rad.)/(cube size)) */
+#endif
+#ifndef  AMBVWT
+#define  AMBVWT		250	/* relative ambient value weight (# calcs) */
+#endif
 
 typedef struct ambtree {
 	AMBVAL	*alist;		/* ambient value list */
@@ -48,11 +53,15 @@ static int  nunflshed = 0;	/* number of unflushed ambi
 #endif
 #endif
 #ifndef SORT_INTVL
-#define SORT_INTVL	(SORT_THRESH*8)
+#define SORT_INTVL	(SORT_THRESH*256)
 #endif
+#ifndef MAX_SORT_INTVL
+#define MAX_SORT_INTVL	(SORT_INTVL<<4)
+#endif
 
+static COLOR  avsum = BLKCOLOR;		/* computed ambient value sum */
+static unsigned int  nambvals = 0;	/* number of computed ambient values */
 static unsigned long  ambclock = 0;	/* ambient access clock */
-static unsigned int  nambvals = 0;	/* number of stored ambient values */
 static unsigned long  lastsort = 0;	/* time of last value sort */
 static long  sortintvl = SORT_INTVL;	/* time until next sort */
 
@@ -63,8 +72,6 @@ static long  sortintvl = SORT_INTVL;	/* time until nex
 	 * claiming our own memory (copy on write).
 	 */
 #define tracktime	(shm_boundary == NULL || ambfp == NULL)
-#define checksort()	if (ambclock > lastsort+sortintvl && \
-			nambvals > SORT_THRESH) sortambvals(0)
 
 #define	 AMBFLUSH	(BUFSIZ/AMBVALSIZ)
 
@@ -88,7 +95,7 @@ int  ar;
 		maxarad = thescene.cusize / 2.0;
 	} else {
 		minarad = thescene.cusize / ar;
-		maxarad = 16 * minarad;			/* heuristic */
+		maxarad = 64 * minarad;			/* heuristic */
 		if (maxarad > thescene.cusize / 2.0)
 			maxarad = thescene.cusize / 2.0;
 	}
@@ -195,26 +202,35 @@ register RAY  *r;
 		rdepth++;
 		d = doambient(acol, r, r->rweight, NULL, NULL);
 		rdepth--;
-		if (d == 0.0)
+		if (d <= FTINY)
 			goto dumbamb;
 		return;
 	}
 						/* resort memory? */
-	checksort();
+	sortambvals(0);
 						/* get ambient value */
 	setcolor(acol, 0.0, 0.0, 0.0);
 	d = sumambient(acol, r, rdepth,
 			&atrunk, thescene.cuorg, thescene.cusize);
-	if (d > FTINY)
+	if (d > FTINY) {
 		scalecolor(acol, 1.0/d);
-	else {
-		d = makeambient(acol, r, rdepth++);
-		rdepth--;
+		return;
 	}
+	rdepth++;
+	d = makeambient(acol, r, rdepth-1);
+	rdepth--;
 	if (d > FTINY)
 		return;
 dumbamb:					/* return global value */
 	copycolor(acol, ambval);
+#if  AMBVWT
+	if (nambvals == 0)
+		return;
+	scalecolor(acol, (double)AMBVWT);
+	addcolor(acol, avsum);			/* average in computations */
+	d = 1.0/(AMBVWT+nambvals);
+	scalecolor(acol, d);
+#endif
 }
 
 
@@ -233,8 +249,9 @@ double	s;
 	int  i;
 	register int  j;
 	register AMBVAL	 *av;
-					/* do this node */
+
 	wsum = 0.0;
+					/* do this node */
 	for (av = at->alist; av != NULL; av = av->next) {
 		if (tracktime)
 			av->latick = ambclock++;
@@ -248,11 +265,12 @@ double	s;
 		/*
 		 *  Ambient radius test.
 		 */
-		e1 = 0.0;
-		for (j = 0; j < 3; j++) {
-			d = av->pos[j] - r->rop[j];
-			e1 += d * d;
-		}
+		d = av->pos[0] - r->rop[0];
+		e1 = d * d;
+		d = av->pos[1] - r->rop[1];
+		e1 += d * d;
+		d = av->pos[2] - r->rop[2];
+		e1 += d * d;
 		e1 /= av->rad * av->rad;
 		if (e1 > ambacc*ambacc*1.21)
 			continue;
@@ -276,8 +294,7 @@ double	s;
 		 *  Jittering final test reduces image artifacts.
 		 */
 		wt = sqrt(e1) + sqrt(e2);
-		wt *= .9 + .2*urand(9015+samplendx);
-		if (wt > ambacc)
+		if (wt > ambacc*(.9+.2*urand(9015+samplendx)))
 			continue;
 		if (wt <= 1e-3)
 			wt = 1e3;
@@ -424,6 +441,7 @@ register AMBVAL  *aval;
 	copystruct(av, aval);
 	av->latick = ambclock;
 	av->next = NULL;
+	addcolor(avsum, av->val);	/* add to sum for averaging */
 	nambvals++;
 	return(av);
 }
@@ -586,6 +604,10 @@ int	always;
 	AMBTREE  oldatrunk;
 	AMBVAL	tav, *tap, *pnext;
 	register int	i, j;
+					/* see if it's time yet */
+	if (!always && (ambclock < lastsort+sortintvl ||
+			nambvals < SORT_THRESH))
+		return;
 	/*
 	 * The idea here is to minimize memory thrashing
 	 * in VM systems by improving reference locality.
@@ -625,7 +647,8 @@ int	always;
 		 * when we're thrashing, which is when we need to do it.
 		 */
 #ifdef DEBUG
-		sprintf(errmsg, "sorting %u ambient values...", nambvals);
+		sprintf(errmsg, "sorting %u ambient values at ambclock=%lu...",
+				nambvals, ambclock);
 		eputs(errmsg);
 #endif
 		i_avlist = 0;
@@ -653,7 +676,11 @@ int	always;
 		}
 		free((char *)avlist1);
 		free((char *)avlist2);
-		if (sortintvl < SORT_INTVL<<6)
+						/* compute new sort interval */
+		sortintvl = ambclock - lastsort;
+		if (sortintvl >= MAX_SORT_INTVL/2)
+			sortintvl = MAX_SORT_INTVL;
+		else
 			sortintvl <<= 1;	/* wait twice as long next */
 #ifdef DEBUG
 		eputs("done\n");