ViewVC Help

View File | Revision Log | Show Annotations | Download File | Root Listing

root/Development/ray/src/rt/ambient.c

Comparing ray/src/rt/ambient.c (file contents):
Revision 1.6 by greg, Tue Aug 8 17:31:23 1989 UTC vs.
Revision 2.7 by greg, Thu Jul 16 13:37:12 1992 UTC

#	Line 1 | Line 1
1	<	/* Copyright (c) 1986 Regents of the University of California */
1	>	/* Copyright (c) 1991 Regents of the University of California */
2
3		#ifndef lint
4		static char SCCSid[] = "$SunId$ LBL";
#	Line 17 | Line 17 | static char SCCSid[] = "$SunId$ LBL";
17
18		#include  "octree.h"
19
20	+	#include  "otypes.h"
21	+
22	+	#include  "ambient.h"
23	+
24		#include  "random.h"
25
26		#define  OCTSCALE       0.5     /* ceil((valid rad.)/(cube size)) */
27
28	<	#define  WDONE          4       /* stop if wsum/wmin is at or above */
28	>	typedef struct ambtree {
29	>	AMBVAL  *alist;         /* ambient value list */
30	>	struct ambtree  *kid;   /* 8 child nodes */
31	>	}  AMBTREE;                     /* ambient octree */
32
33		extern CUBE  thescene;          /* contains space boundaries */
34
35	<	extern COLOR  ambval;           /* global ambient component */
36	<	extern double  ambacc;          /* ambient accuracy */
30	<	extern int  ambres;             /* ambient resolution */
31	<	extern int  ambdiv;             /* number of divisions for calculation */
32	<	extern int  ambssamp;           /* number of super-samples */
33	<	extern int  ambounce;           /* number of ambient bounces */
34	<	extern char  *amblist[];        /* ambient include/exclude list */
35	<	extern int  ambincl;            /* include == 1, exclude == 0 */
35	>	#define  MAXASET        511     /* maximum number of elements in ambient set */
36	>	OBJECT  ambset[MAXASET+1]={0};  /* ambient include/exclude set */
37
37	–	OBJECT  ambset[128];            /* ambient include/exclude set */
38	–
38		double  maxarad;                /* maximum ambient radius */
39		double  minarad;                /* minimum ambient radius */
40
42	–	typedef struct ambval {
43	–	FVECT  pos;             /* position in space */
44	–	FVECT  dir;             /* normal direction */
45	–	int  lvl;               /* recursion level of parent ray */
46	–	float  weight;          /* weight of parent ray */
47	–	COLOR  val;             /* computed ambient value */
48	–	float  rad;             /* validity radius */
49	–	struct ambval  *next;   /* next in list */
50	–	}  AMBVAL;                      /* ambient value */
51	–
52	–	typedef struct ambtree {
53	–	AMBVAL  *alist;         /* ambient value list */
54	–	struct ambtree  *kid;   /* 8 child nodes */
55	–	}  AMBTREE;                     /* ambient octree */
56	–
57	–	typedef struct {
58	–	float  k;               /* error contribution per sample */
59	–	COLOR  v;               /* ray sum */
60	–	int  n;                 /* number of samples */
61	–	short  t, p;            /* theta, phi indices */
62	–	}  AMBSAMP;                     /* ambient sample */
63	–
41		static AMBTREE  atrunk;         /* our ambient trunk node */
42
43		static FILE  *ambfp = NULL;     /* ambient file pointer */
44	+	static char  *afname;           /* ambient file name */
45	+	static long  ambheadlen;        /* length of ambient file header */
46
47	+	#define  AMBFLUSH       (BUFSIZ/AMBVALSIZ)
48	+
49		#define  newambval()    (AMBVAL *)bmalloc(sizeof(AMBVAL))
50
51		#define  newambtree()   (AMBTREE *)calloc(8, sizeof(AMBTREE))
52
53	<	double  sumambient(), doambient(), makeambient();
53	>	extern long  ftell(), lseek();
54
55
56	+	setambres(ar)                           /* set ambient resolution */
57	+	int  ar;
58	+	{
59	+	/* set min & max radii */
60	+	if (ar <= 0) {
61	+	minarad = 0.0;
62	+	maxarad = thescene.cusize / 2.0;
63	+	} else {
64	+	minarad = thescene.cusize / ar;
65	+	maxarad = 16.0 * minarad;               /* heuristic */
66	+	if (maxarad > thescene.cusize / 2.0)
67	+	maxarad = thescene.cusize / 2.0;
68	+	}
69	+	if (maxarad <= FTINY)
70	+	maxarad = .001;
71	+	}
72	+
73	+
74		setambient(afile)                       /* initialize calculation */
75		char  *afile;
76		{
78	–	long  ftell();
79	–	char  **amblp;
80	–	OBJECT  obj;
77		AMBVAL  amb;
78	<	/* set up ambient set */
79	<	ambset[0] = 0;
80	<	for (amblp = amblist; *amblp != NULL; amblp++) {
81	<	if ((obj = modifier(*amblp)) == OVOID) {
86	<	sprintf(errmsg, "unknown %s modifier \"%s\"",
87	<	ambincl ? "include" : "exclude", *amblp);
88	<	error(WARNING, errmsg);
89	<	continue;
90	<	}
91	<	if (!inset(ambset, obj))
92	<	insertelem(ambset, obj);
93	<	}
94	<	maxarad = thescene.cusize / 2.0;                /* maximum radius */
95	<	/* minimum radius */
96	<	minarad = ambres > 0 ? thescene.cusize/ambres : 0.0;
97	<
98	<	/* open ambient file */
99	<	if (afile != NULL)
78	>	/* init ambient limits */
79	>	setambres(ambres);
80	>	/* open ambient file */
81	>	if ((afname = afile) != NULL)
82		if ((ambfp = fopen(afile, "r+")) != NULL) {
83	<	while (fread(&amb, sizeof(AMBVAL), 1, ambfp) == 1)
83	>	initambfile(0);
84	>	while (readambval(&amb, ambfp))
85		avinsert(&amb, &atrunk, thescene.cuorg,
86		thescene.cusize);
87		/* align */
88	<	fseek(ambfp, -(ftell(ambfp)%sizeof(AMBVAL)), 1);
89	<	} else if ((ambfp = fopen(afile, "w")) == NULL) {
88	>	fseek(ambfp, -((ftell(ambfp)-ambheadlen)%AMBVALSIZ), 1);
89	>	} else if ((ambfp = fopen(afile, "w")) != NULL)
90	>	initambfile(1);
91	>	else {
92		sprintf(errmsg, "cannot open ambient file \"%s\"",
93		afile);
94		error(SYSTEM, errmsg);
#	Line 111 | Line 96 | char  *afile;
96		}
97
98
99	+	initambfile(creat)              /* initialize ambient file */
100	+	int  creat;
101	+	{
102	+	extern char  *progname, *octname;
103	+
104	+	setbuf(ambfp, bmalloc(BUFSIZ));
105	+	if (creat) {                    /* new file */
106	+	fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
107	+	progname, colval(ambval,RED),
108	+	colval(ambval,GRN), colval(ambval,BLU),
109	+	ambounce, ambacc);
110	+	fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
111	+	ambdiv, ambssamp, ambres,
112	+	octname==NULL ? "" : octname);
113	+	fputformat(AMBFMT, ambfp);
114	+	putc('\n', ambfp);
115	+	putambmagic(ambfp);
116	+	fflush(ambfp);
117	+	} else if (checkheader(ambfp, AMBFMT, NULL) < 0
118	+	|| !hasambmagic(ambfp)) {
119	+	sprintf(errmsg, "\"%s\" is not an ambient file", afname);
120	+	error(USER, afname);
121	+	}
122	+	ambheadlen = ftell(ambfp);
123	+	}
124	+
125	+
126	+	ambnotify(obj)                  /* record new modifier */
127	+	OBJECT  obj;
128	+	{
129	+	static int  hitlimit = 0;
130	+	register OBJREC  *o = objptr(obj);
131	+	register char  **amblp;
132	+
133	+	if (hitlimit || !ismodifier(o->otype))
134	+	return;
135	+	for (amblp = amblist; *amblp != NULL; amblp++)
136	+	if (!strcmp(o->oname, *amblp)) {
137	+	if (ambset[0] >= MAXASET) {
138	+	error(WARNING, "too many modifiers in ambient list");
139	+	hitlimit++;
140	+	return;         /* should this be fatal? */
141	+	}
142	+	insertelem(ambset, obj);
143	+	return;
144	+	}
145	+	}
146	+
147	+
148		ambient(acol, r)                /* compute ambient component for ray */
149		COLOR  acol;
150		register RAY  *r;
151		{
152		static int  rdepth = 0;                 /* ambient recursion */
153	<	double  wsum;
153	>	double  d;
154
121	–	rdepth++;                               /* increment level */
122	–
155		if (ambdiv <= 0)                        /* no ambient calculation */
156		goto dumbamb;
157		/* check number of bounces */
158	<	if (rdepth > ambounce)
158	>	if (rdepth >= ambounce)
159		goto dumbamb;
160		/* check ambient list */
161		if (ambincl != -1 && r->ro != NULL &&
#	Line 131 | Line 163 | register RAY  *r;
163		goto dumbamb;
164
165		if (ambacc <= FTINY) {                  /* no ambient storage */
166	<	if (doambient(acol, r) == 0.0)
166	>	rdepth++;
167	>	d = doambient(acol, r, r->rweight, NULL, NULL);
168	>	rdepth--;
169	>	if (d == 0.0)
170		goto dumbamb;
171	<	goto done;
171	>	return;
172		}
173		/* get ambient value */
174		setcolor(acol, 0.0, 0.0, 0.0);
175	<	wsum = sumambient(acol, r, &atrunk, thescene.cuorg, thescene.cusize);
176	<	if (wsum > FTINY)
177	<	scalecolor(acol, 1.0/wsum);
178	<	else if (makeambient(acol, r) == 0.0)
179	<	goto dumbamb;
180	<	goto done;
181	<
175	>	d = sumambient(acol, r, rdepth,
176	>	&atrunk, thescene.cuorg, thescene.cusize);
177	>	if (d > FTINY)
178	>	scalecolor(acol, 1.0/d);
179	>	else {
180	>	d = makeambient(acol, r, rdepth++);
181	>	rdepth--;
182	>	}
183	>	if (d > FTINY)
184	>	return;
185		dumbamb:                                        /* return global value */
186		copycolor(acol, ambval);
149	–	done:                                           /* must finish here! */
150	–	rdepth--;
187		}
188
189
190		double
191	<	sumambient(acol, r, at, c0, s)          /* get interpolated ambient value */
191	>	sumambient(acol, r, al, at, c0, s)      /* get interpolated ambient value */
192		COLOR  acol;
193		register RAY  *r;
194	+	int  al;
195		AMBTREE  *at;
196		FVECT  c0;
197		double  s;
#	Line 166 | Line 203 | double  s;
203		int  i;
204		register int  j;
205		register AMBVAL  *av;
206	<
206	>	/* do this node */
207		wsum = 0.0;
171	–	/* check children first */
172	–	if (at->kid != NULL) {
173	–	s *= 0.5;
174	–	for (i = 0; i < 8; i++) {
175	–	for (j = 0; j < 3; j++) {
176	–	ck0[j] = c0[j];
177	–	if (1<<j & i)
178	–	ck0[j] += s;
179	–	if (r->rop[j] < ck0[j] - OCTSCALE*s)
180	–	break;
181	–	if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
182	–	break;
183	–	}
184	–	if (j == 3)
185	–	wsum += sumambient(acol, r, at->kid+i, ck0, s);
186	–	}
187	–	if (wsum*ambacc >= WDONE)
188	–	return(wsum);           /* close enough */
189	–	}
190	–	/* check this node */
208		for (av = at->alist; av != NULL; av = av->next) {
209		/*
210	<	*  Ray strength test.
210	>	*  Ambient level test.
211		*/
212	<	if (av->lvl > r->rlvl || av->weight < r->rweight-FTINY)
212	>	if (av->lvl > al || av->weight < r->rweight-FTINY)
213		continue;
214		/*
215		*  Ambient radius test.
#	Line 219 | Line 236 | double  s;
236		for (j = 0; j < 3; j++)
237		d += (r->rop[j] - av->pos[j]) *
238		(av->dir[j] + r->ron[j]);
239	<	if (d < -minarad)
239	>	if (d*0.5 < -minarad*ambacc-.001)
240		continue;
241		/*
242		*  Jittering final test reduces image artifacts.
243		*/
244		wt = sqrt(e1) + sqrt(e2);
245	<	wt *= 0.9 + 0.2*frandom();
245	>	wt *= .9 + .2*urand(9015+samplendx);
246		if (wt > ambacc)
247		continue;
248		if (wt <= 1e-3)
#	Line 233 | Line 250 | double  s;
250		else
251		wt = 1.0 / wt;
252		wsum += wt;
253	<	copycolor(ct, av->val);
253	>	extambient(ct, av, r->rop, r->ron);
254		scalecolor(ct, wt);
255		addcolor(acol, ct);
256		}
257	+	if (at->kid == NULL)
258	+	return(wsum);
259	+	/* do children */
260	+	s *= 0.5;
261	+	for (i = 0; i < 8; i++) {
262	+	for (j = 0; j < 3; j++) {
263	+	ck0[j] = c0[j];
264	+	if (1<<j & i)
265	+	ck0[j] += s;
266	+	if (r->rop[j] < ck0[j] - OCTSCALE*s)
267	+	break;
268	+	if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
269	+	break;
270	+	}
271	+	if (j == 3)
272	+	wsum += sumambient(acol, r, al, at->kid+i, ck0, s);
273	+	}
274		return(wsum);
275		}
276
277
278		double
279	<	makeambient(acol, r)            /* make a new ambient value */
279	>	makeambient(acol, r, al)        /* make a new ambient value */
280		COLOR  acol;
281		register RAY  *r;
282	+	int  al;
283		{
284		AMBVAL  amb;
285	<
286	<	amb.rad = doambient(acol, r);           /* compute ambient */
285	>	FVECT   gp, gd;
286	>	/* compute weight */
287	>	amb.weight = pow(AVGREFL, (double)al);
288	>	if (r->rweight < 0.2*amb.weight)        /* heuristic */
289	>	amb.weight = r->rweight;
290	>	/* compute ambient */
291	>	amb.rad = doambient(acol, r, amb.weight, gp, gd);
292		if (amb.rad == 0.0)
293		return(0.0);
294		/* store it */
295		VCOPY(amb.pos, r->rop);
296		VCOPY(amb.dir, r->ron);
297	<	amb.lvl = r->rlvl;
258	<	amb.weight = r->rweight;
297	>	amb.lvl = al;
298		copycolor(amb.val, acol);
299	+	VCOPY(amb.gpos, gp);
300	+	VCOPY(amb.gdir, gd);
301		/* insert into tree */
302	<	avinsert(&amb, &atrunk, thescene.cuorg, thescene.cusize);
262	<	avsave(&amb);                           /* write to file */
302	>	avsave(&amb);                           /* and save to file */
303		return(amb.rad);
304		}
305
306
307	<	double
308	<	doambient(acol, r)                      /* compute ambient component */
309	<	COLOR  acol;
310	<	register RAY  *r;
307	>	extambient(cr, ap, pv, nv)              /* extrapolate value at pv, nv */
308	>	COLOR  cr;
309	>	register AMBVAL  *ap;
310	>	FVECT  pv, nv;
311		{
312	<	extern int  ambcmp();
313	<	extern double  sin(), cos(), sqrt();
314	<	double  phi, xd, yd, zd;
275	<	double  b, b2;
276	<	register AMBSAMP  *div;
277	<	AMBSAMP  dnew;
278	<	RAY  ar;
279	<	FVECT  ux, uy;
280	<	double  arad;
281	<	int  ndivs, nt, np, ns, ne, i, j;
282	<	register int  k;
312	>	FVECT  v1, v2;
313	>	register int  i;
314	>	double  d;
315
316	<	setcolor(acol, 0.0, 0.0, 0.0);
317	<	/* set number of divisions */
318	<	nt = sqrt(ambdiv * r->rweight * 0.5) + 0.5;
319	<	np = 2 * nt;
320	<	ndivs = nt * np;
321	<	/* check first */
322	<	if (ndivs == 0 || rayorigin(&ar, r, AMBIENT, 0.5) < 0)
323	<	return(0.0);
324	<	/* set number of super-samples */
325	<	ns = ambssamp * r->rweight + 0.5;
326	<	if (ns > 0) {
295	<	div = (AMBSAMP *)malloc(ndivs*sizeof(AMBSAMP));
296	<	if (div == NULL)
297	<	error(SYSTEM, "out of memory in doambient");
316	>	d = 1.0;                        /* zeroeth order */
317	>	/* gradient due to translation */
318	>	for (i = 0; i < 3; i++)
319	>	d += ap->gpos[i]*(pv[i]-ap->pos[i]);
320	>	/* gradient due to rotation */
321	>	VCOPY(v1, ap->dir);
322	>	fcross(v2, v1, nv);
323	>	d += DOT(ap->gdir, v2);
324	>	if (d <= 0.0) {
325	>	setcolor(cr, 0.0, 0.0, 0.0);
326	>	return;
327		}
328	<	/* make axes */
329	<	uy[0] = uy[1] = uy[2] = 0.0;
301	<	for (k = 0; k < 3; k++)
302	<	if (r->ron[k] < 0.6 && r->ron[k] > -0.6)
303	<	break;
304	<	uy[k] = 1.0;
305	<	fcross(ux, r->ron, uy);
306	<	normalize(ux);
307	<	fcross(uy, ux, r->ron);
308	<	/* sample divisions */
309	<	arad = 0.0;
310	<	ne = 0;
311	<	for (i = 0; i < nt; i++)
312	<	for (j = 0; j < np; j++) {
313	<	rayorigin(&ar, r, AMBIENT, 0.5);        /* pretested */
314	<	zd = sqrt((i+frandom())/nt);
315	<	phi = 2.0*PI * (j+frandom())/np;
316	<	xd = cos(phi) * zd;
317	<	yd = sin(phi) * zd;
318	<	zd = sqrt(1.0 - zd*zd);
319	<	for (k = 0; k < 3; k++)
320	<	ar.rdir[k] = xd*ux[k]+yd*uy[k]+zd*r->ron[k];
321	<	rayvalue(&ar);
322	<	if (ar.rot < FHUGE)
323	<	arad += 1.0 / ar.rot;
324	<	if (ns > 0) {                   /* save division */
325	<	div[ne].k = 0.0;
326	<	copycolor(div[ne].v, ar.rcol);
327	<	div[ne].n = 0;
328	<	div[ne].t = i; div[ne].p = j;
329	<	/* sum errors */
330	<	b = bright(ar.rcol);
331	<	if (i > 0) {            /* from above */
332	<	b2 = bright(div[ne-np].v) - b;
333	<	b2 *= b2 * 0.25;
334	<	div[ne].k += b2;
335	<	div[ne].n++;
336	<	div[ne-np].k += b2;
337	<	div[ne-np].n++;
338	<	}
339	<	if (j > 0) {            /* from behind */
340	<	b2 = bright(div[ne-1].v) - b;
341	<	b2 *= b2 * 0.25;
342	<	div[ne].k += b2;
343	<	div[ne].n++;
344	<	div[ne-1].k += b2;
345	<	div[ne-1].n++;
346	<	}
347	<	if (j == np-1) {        /* around */
348	<	b2 = bright(div[ne-(np-1)].v) - b;
349	<	b2 *= b2 * 0.25;
350	<	div[ne].k += b2;
351	<	div[ne].n++;
352	<	div[ne-(np-1)].k += b2;
353	<	div[ne-(np-1)].n++;
354	<	}
355	<	ne++;
356	<	} else
357	<	addcolor(acol, ar.rcol);
358	<	}
359	<	for (k = 0; k < ne; k++) {              /* compute errors */
360	<	if (div[k].n > 1)
361	<	div[k].k /= div[k].n;
362	<	div[k].n = 1;
363	<	}
364	<	/* sort the divisions */
365	<	qsort(div, ne, sizeof(AMBSAMP), ambcmp);
366	<	/* skim excess */
367	<	while (ne > ns) {
368	<	ne--;
369	<	addcolor(acol, div[ne].v);
370	<	}
371	<	/* super-sample */
372	<	for (i = ns; i > 0; i--) {
373	<	rayorigin(&ar, r, AMBIENT, 0.5);        /* pretested */
374	<	zd = sqrt((div[0].t+frandom())/nt);
375	<	phi = 2.0*PI * (div[0].p+frandom())/np;
376	<	xd = cos(phi) * zd;
377	<	yd = sin(phi) * zd;
378	<	zd = sqrt(1.0 - zd*zd);
379	<	for (k = 0; k < 3; k++)
380	<	ar.rdir[k] = xd*ux[k]+yd*uy[k]+zd*r->ron[k];
381	<	rayvalue(&ar);
382	<	if (ar.rot < FHUGE)
383	<	arad += 1.0 / ar.rot;
384	<	/* recompute error */
385	<	copycolor(dnew.v, div[0].v);
386	<	addcolor(dnew.v, ar.rcol);
387	<	dnew.n = div[0].n + 1;
388	<	dnew.t = div[0].t; dnew.p = div[0].p;
389	<	b2 = bright(dnew.v)/dnew.n - bright(ar.rcol);
390	<	b2 = b2*b2 + div[0].k*(div[0].n*div[0].n);
391	<	dnew.k = b2/(dnew.n*dnew.n);
392	<	/* reinsert */
393	<	for (k = 0; k < ne-1 && dnew.k < div[k+1].k; k++)
394	<	bcopy(&div[k+1], &div[k], sizeof(AMBSAMP));
395	<	bcopy(&dnew, &div[k], sizeof(AMBSAMP));
396	<
397	<	if (ne >= i) {          /* extract darkest division */
398	<	ne--;
399	<	if (div[ne].n > 1)
400	<	scalecolor(div[ne].v, 1.0/div[ne].n);
401	<	addcolor(acol, div[ne].v);
402	<	}
403	<	}
404	<	scalecolor(acol, 1.0/ndivs);
405	<	if (arad <= FTINY)
406	<	arad = FHUGE;
407	<	else
408	<	arad = (ndivs+ns) / arad / sqrt(r->rweight);
409	<	if (arad > maxarad)
410	<	arad = maxarad;
411	<	else if (arad < minarad)
412	<	arad = minarad;
413	<	if (ns > 0)
414	<	free((char *)div);
415	<	return(arad);
328	>	copycolor(cr, ap->val);
329	>	scalecolor(cr, d);
330		}
331
332
419	–	static int
420	–	ambcmp(d1, d2)                          /* decreasing order */
421	–	AMBSAMP  *d1, *d2;
422	–	{
423	–	if (d1->k < d2->k)
424	–	return(1);
425	–	if (d1->k > d2->k)
426	–	return(-1);
427	–	return(0);
428	–	}
429	–
430	–
333		static
334	<	avsave(av)                              /* save an ambient value */
334	>	avsave(av)                              /* insert and save an ambient value */
335		AMBVAL  *av;
336		{
435	–	#ifdef  AMBFLUSH
337		static int  nunflshed = 0;
338	<	#endif
338	>
339	>	avinsert(av, &atrunk, thescene.cuorg, thescene.cusize);
340		if (ambfp == NULL)
341		return;
342	<	if (fwrite(av, sizeof(AMBVAL), 1, ambfp) != 1)
342	>	if (writambval(av, ambfp) < 0)
343		goto writerr;
442	–	#ifdef  AMBFLUSH
344		if (++nunflshed >= AMBFLUSH) {
345	<	if (fflush(ambfp) == EOF)
345	>	if (ambsync() == EOF)
346		goto writerr;
347		nunflshed = 0;
348		}
448	–	#endif
349		return;
350		writerr:
351		error(SYSTEM, "error writing ambient file");
#	Line 466 | Line 366 | double  s;
366
367		if ((av = newambval()) == NULL)
368		goto memerr;
369	<	bcopy(aval, av, sizeof(AMBVAL));
369	>	copystruct(av, aval);
370		VCOPY(ck0, c0);
371		while (s*(OCTSCALE/2) > av->rad*ambacc) {
372		if (at->kid == NULL)
#	Line 486 | Line 386 | double  s;
386		return;
387		memerr:
388		error(SYSTEM, "out of memory in avinsert");
389	+	}
390	+
391	+
392	+	#include  <fcntl.h>
393	+
394	+
395	+	static
396	+	ambsync()                       /* synchronize ambient file */
397	+	{
398	+	static FILE  *ambinp = NULL;
399	+	struct flock  fls;
400	+	AMBVAL  avs;
401	+	long  lastpos, flen;
402	+	register int  n;
403	+	/* gain exclusive access */
404	+	fls.l_type = F_WRLCK;
405	+	fls.l_whence = 0;
406	+	fls.l_start = 0L;
407	+	fls.l_len = 0L;
408	+	if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
409	+	error(SYSTEM, "cannot lock ambient file");
410	+	/* see if file has grown */
411	+	lastpos = lseek(fileno(ambfp), 0L, 2);  /* may move pointer */
412	+	flen = lseek(fileno(ambfp), 0L, 1);     /* new(?) file length */
413	+	if (n = (flen - lastpos)%AMBVALSIZ)     /* assure alignment */
414	+	lseek(fileno(ambfp), flen -= n, 0);
415	+	if (n = (flen - lastpos)/AMBVALSIZ) {   /* file has grown */
416	+	if (ambinp == NULL && (ambinp = fopen(afname, "r")) == NULL)
417	+	error(SYSTEM, "cannot reopen ambient file");
418	+	fseek(ambinp, lastpos, 0);      /* go to previous position */
419	+	while (n--) {                   /* load contributed values */
420	+	readambval(&avs, ambinp);
421	+	avinsert(&avs,&atrunk,thescene.cuorg,thescene.cusize);
422	+	}
423	+	}
424	+	n = fflush(ambfp);                      /* calls write() at last */
425	+	fls.l_type = F_UNLCK;                   /* release file */
426	+	fcntl(fileno(ambfp), F_SETLKW, &fls);
427	+	return(n);
428		}

Diff Legend

–	Removed lines
+	Added lines
<	Changed lines (old)
>	Changed lines (new)