--- ray/src/rt/ambient.c	1993/08/04 14:22:11	2.19
+++ ray/src/rt/ambient.c	1994/06/02 11:45:27	2.25
@@ -43,9 +43,11 @@ static int  nunflshed = 0;	/* number of unflushed ambi
 #define	 newambval()	(AMBVAL *)bmalloc(sizeof(AMBVAL))
 
 #define	 newambtree()	(AMBTREE *)calloc(8, sizeof(AMBTREE))
+#define  freeambtree(t)	free((char *)(t))
 
 extern long  ftell(), lseek();
-static int  initambfile(), avsave(), avinsert();
+static int  initambfile(), avsave(), avinsert(), loadatree();
+static AMBVAL  *avstore();
 #ifdef  F_SETLKW
 static  aflock();
 #endif
@@ -54,21 +56,46 @@ static  aflock();
 setambres(ar)				/* set ambient resolution */
 int  ar;
 {
+	ambres = ar < 0 ? 0 : ar;		/* may be done already */
 						/* set min & max radii */
 	if (ar <= 0) {
-		minarad = 0.0;
+		minarad = 0;
 		maxarad = thescene.cusize / 2.0;
 	} else {
 		minarad = thescene.cusize / ar;
-		maxarad = 16.0 * minarad;		/* heuristic */
+		maxarad = 16 * minarad;			/* heuristic */
 		if (maxarad > thescene.cusize / 2.0)
 			maxarad = thescene.cusize / 2.0;
 	}
-	if (maxarad <= FTINY)
-		maxarad = .001;
+	if (minarad <= FTINY)
+		minarad = 10*FTINY;
+	if (maxarad <= minarad)
+		maxarad = 64 * minarad;
 }
 
 
+setambacc(newa)				/* set ambient accuracy */
+double  newa;
+{
+	static double  oldambacc = -1.0;
+	AMBTREE  oldatrunk;
+
+	ambacc = newa < 0.0 ? 0.0 : newa;	/* may be done already */
+	if (oldambacc < -FTINY)
+		oldambacc = ambacc;	/* do nothing first call */
+	if (fabs(newa - oldambacc) < 0.01)
+		return;			/* insignificant -- don't bother */
+	if (ambacc <= FTINY)
+		return;			/* cannot build new tree */
+					/* else need to rebuild tree */
+	copystruct(&oldatrunk, &atrunk);
+	atrunk.alist = NULL;
+	atrunk.kid = NULL;
+	loadatree(&oldatrunk);
+	oldambacc = ambacc;		/* remeber setting for next call */
+}
+
+
 setambient(afile)			/* initialize calculation */
 char  *afile;
 {
@@ -76,15 +103,21 @@ char  *afile;
 	AMBVAL	amb;
 						/* init ambient limits */
 	setambres(ambres);
+	setambacc(ambacc);
 	if (afile == NULL)
 		return;
+	if (ambacc <= FTINY) {
+		sprintf(errmsg, "zero ambient accuracy so \"%s\" not opened",
+				afile);
+		error(WARNING, errmsg);
+		return;
+	}
 						/* open ambient file */
 	if ((ambfp = fopen(afile, "r+")) != NULL) {
 		initambfile(0);
 		headlen = ftell(ambfp);
 		while (readambval(&amb, ambfp))
-			avinsert(&amb, &atrunk, thescene.cuorg,
-					thescene.cusize);
+			avinsert(avstore(&amb));
 						/* align */
 		fseek(ambfp, -((ftell(ambfp)-headlen)%AMBVALSIZ), 1);
 	} else if ((ambfp = fopen(afile, "w+")) != NULL)
@@ -183,7 +216,9 @@ double	s;
 		/*
 		 *  Ambient level test.
 		 */
-		if (av->lvl > al || av->weight < r->rweight-FTINY)
+		if (av->lvl > al)	/* list sorted, so this works */
+			break;
+		if (av->weight < r->rweight-FTINY)
 			continue;
 		/*
 		 *  Ambient radius test.
@@ -316,8 +351,9 @@ int  creat;
 #ifdef MSDOS
 	setmode(fileno(ambfp), O_BINARY);
 #endif
-	setbuf(ambfp, bmalloc(BUFSIZ));
+	setbuf(ambfp, bmalloc(BUFSIZ+8));
 	if (creat) {			/* new file */
+		newheader("RADIANCE", ambfp);
 		fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
 				progname, colval(ambval,RED),
 				colval(ambval,GRN), colval(ambval,BLU),
@@ -338,7 +374,7 @@ static
 avsave(av)				/* insert and save an ambient value */
 AMBVAL	*av;
 {
-	avinsert(av, &atrunk, thescene.cuorg, thescene.cusize);
+	avinsert(avstore(av));
 	if (ambfp == NULL)
 		return;
 	if (writambval(av, ambfp) < 0)
@@ -352,26 +388,40 @@ writerr:
 }
 
 
+static AMBVAL *
+avstore(aval)				/* allocate memory and store aval */
+register AMBVAL  *aval;
+{
+	register AMBVAL  *av;
+
+	if ((av = newambval()) == NULL)
+		error(SYSTEM, "out of memory in avstore");
+	copystruct(av, aval);
+	return(av);
+}
+
+
 static
-avinsert(aval, at, c0, s)		/* insert ambient value in a tree */
-AMBVAL	*aval;
-register AMBTREE  *at;
-FVECT  c0;
-double	s;
+avinsert(av)				/* insert ambient value in our tree */
+register AMBVAL	 *av;
 {
+	register AMBTREE  *at;
+	register AMBVAL  *ap;
+	AMBVAL  avh;
 	FVECT  ck0;
+	double	s;
 	int  branch;
-	register AMBVAL	 *av;
 	register int  i;
 
-	if ((av = newambval()) == NULL)
-		goto memerr;
-	copystruct(av, aval);
-	VCOPY(ck0, c0);
+	if (av->rad <= FTINY)
+		error(CONSISTENCY, "zero ambient radius in avinsert");
+	at = &atrunk;
+	VCOPY(ck0, thescene.cuorg);
+	s = thescene.cusize;
 	while (s*(OCTSCALE/2) > av->rad*ambacc) {
 		if (at->kid == NULL)
 			if ((at->kid = newambtree()) == NULL)
-				goto memerr;
+				error(SYSTEM, "out of memory in avinsert");
 		s *= 0.5;
 		branch = 0;
 		for (i = 0; i < 3; i++)
@@ -381,14 +431,35 @@ double	s;
 			}
 		at = at->kid + branch;
 	}
-	av->next = at->alist;
-	at->alist = av;
-	return;
-memerr:
-	error(SYSTEM, "out of memory in avinsert");
+	avh.next = at->alist;		/* order by increasing level */
+	for (ap = &avh; ap->next != NULL; ap = ap->next)
+		if (ap->next->lvl >= av->lvl)
+			break;
+	av->next = ap->next;
+	ap->next = av;
+	at->alist = avh.next;
 }
 
 
+static
+loadatree(at)				/* move tree to main store */
+register AMBTREE  *at;
+{
+	register AMBVAL  *av;
+	register int  i;
+					/* transfer values at this node */
+	for (av = at->alist; av != NULL; av = at->alist) {
+		at->alist = av->next;
+		avinsert(av);
+	}
+	if (at->kid == NULL)
+		return;
+	for (i = 0; i < 8; i++)		/* transfer and free children */
+		loadatree(at->kid+i);
+	freeambtree(at->kid);
+}
+
+
 #ifdef	F_SETLKW
 
 static
@@ -420,7 +491,7 @@ ambsync()			/* synchronize ambient file */
 	aflock(F_WRLCK);
 				/* see if file has grown */
 	if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
-		error(SYSTEM, "cannot seek on ambient file");
+		goto seekerr;
 	if (n = flen - lastpos) {		/* file has grown */
 		if (ambinp == NULL) {		/* use duplicate filedes */
 			ambinp = fdopen(dup(fileno(ambfp)), "r");
@@ -428,21 +499,34 @@ ambsync()			/* synchronize ambient file */
 				error(SYSTEM, "fdopen failed in ambsync");
 		}
 		if (fseek(ambinp, lastpos, 0) < 0)
-			error(SYSTEM, "fseek failed in ambsync");
+			goto seekerr;
 		while (n >= AMBVALSIZ) {	/* load contributed values */
 			readambval(&avs, ambinp);
-			avinsert(&avs,&atrunk,thescene.cuorg,thescene.cusize);
+			avinsert(avstore(&avs));
 			n -= AMBVALSIZ;
 		}
-		if (n)				/* alignment */
-			lseek(fileno(ambfp), flen-n, 0);
+		/*** seek always as safety measure
+		if (n) ***/			/* alignment */
+			if (lseek(fileno(ambfp), flen-n, 0) < 0)
+				goto seekerr;
 	}
+#ifdef  DEBUG
+	if (ambfp->_ptr - ambfp->_base != nunflshed*AMBVALSIZ) {
+		sprintf(errmsg, "ambient file buffer at %d rather than %d",
+				ambfp->_ptr - ambfp->_base,
+				nunflshed*AMBVALSIZ);
+		error(CONSISTENCY, errmsg);
+	}
+#endif
 syncend:
 	n = fflush(ambfp);			/* calls write() at last */
-	lastpos = lseek(fileno(ambfp), 0L, 1);
+	if ((lastpos = lseek(fileno(ambfp), 0L, 1)) < 0)
+		goto seekerr;
 	aflock(F_UNLCK);			/* release file */
 	nunflshed = 0;
 	return(n);
+seekerr:
+	error(SYSTEM, "seek failed in ambsync");
 }
 
 #else