src/rt/ambient.c

/* Copyright (c) 1993 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#endif

/*
 *  ambient.c - routines dealing with ambient (inter-reflected) component.
 */

#include  "ray.h"

#include  "octree.h"

#include  "otypes.h"

#include  "ambient.h"

#include  "random.h"

#define  OCTSCALE       0.5     /* ceil((valid rad.)/(cube size)) */

typedef struct ambtree {
        AMBVAL  *alist;         /* ambient value list */
        struct ambtree  *kid;   /* 8 child nodes */
}  AMBTREE;                     /* ambient octree */

extern CUBE  thescene;          /* contains space boundaries */

#define  MAXASET        511     /* maximum number of elements in ambient set */
OBJECT  ambset[MAXASET+1]={0};  /* ambient include/exclude set */

double  maxarad;                /* maximum ambient radius */
double  minarad;                /* minimum ambient radius */

static AMBTREE  atrunk;         /* our ambient trunk node */

static char  *ambfname = NULL;  /* ambient file name */
static FILE  *ambfp = NULL;     /* ambient file pointer */

#define  AMBFLUSH       (BUFSIZ/AMBVALSIZ)

#define  newambval()    (AMBVAL *)bmalloc(sizeof(AMBVAL))

#define  newambtree()   (AMBTREE *)calloc(8, sizeof(AMBTREE))

extern long  ftell(), lseek();
static int  initambfile(), avsave(), avinsert(), ambsync();


setambres(ar)                           /* set ambient resolution */
int  ar;
{
                                                /* set min & max radii */
        if (ar <= 0) {
                minarad = 0.0;
                maxarad = thescene.cusize / 2.0;
        } else {
                minarad = thescene.cusize / ar;
                maxarad = 16.0 * minarad;               /* heuristic */
                if (maxarad > thescene.cusize / 2.0)
                        maxarad = thescene.cusize / 2.0;
        }
        if (maxarad <= FTINY)
                maxarad = .001;
}


setambient(afile)                       /* initialize calculation */
char  *afile;
{
        long  headlen;
        AMBVAL  amb;
                                                /* init ambient limits */
        setambres(ambres);
                                                /* open ambient file */
        if ((ambfname = afile) != NULL)
                if ((ambfp = fopen(afile, "r+")) != NULL) {
                        initambfile(0);
                        headlen = ftell(ambfp);
                        while (readambval(&amb, ambfp))
                                avinsert(&amb, &atrunk, thescene.cuorg,
                                                thescene.cusize);
                                                        /* align */
                        fseek(ambfp, -((ftell(ambfp)-headlen)%AMBVALSIZ), 1);
                } else if ((ambfp = fopen(afile, "w+")) != NULL)
                        initambfile(1);
                else {
                        sprintf(errmsg, "cannot open ambient file \"%s\"",
                                        afile);
                        error(SYSTEM, errmsg);
                }
}


ambnotify(obj)                  /* record new modifier */
OBJECT  obj;
{
        static int  hitlimit = 0;
        register OBJREC  *o = objptr(obj);
        register char  **amblp;

        if (hitlimit || !ismodifier(o->otype))
                return;
        for (amblp = amblist; *amblp != NULL; amblp++)
                if (!strcmp(o->oname, *amblp)) {
                        if (ambset[0] >= MAXASET) {
                                error(WARNING, "too many modifiers in ambient list");
                                hitlimit++;
                                return;         /* should this be fatal? */
                        }
                        insertelem(ambset, obj);
                        return;
                }
}


ambient(acol, r)                /* compute ambient component for ray */
COLOR  acol;
register RAY  *r;
{
        static int  rdepth = 0;                 /* ambient recursion */
        double  d;

        if (ambdiv <= 0)                        /* no ambient calculation */
                goto dumbamb;
                                                /* check number of bounces */
        if (rdepth >= ambounce)
                goto dumbamb;
                                                /* check ambient list */
        if (ambincl != -1 && r->ro != NULL &&
                        ambincl != inset(ambset, r->ro->omod))
                goto dumbamb;

        if (ambacc <= FTINY) {                  /* no ambient storage */
                rdepth++;
                d = doambient(acol, r, r->rweight, NULL, NULL);
                rdepth--;
                if (d == 0.0)
                        goto dumbamb;
                return;
        }
                                                /* get ambient value */
        setcolor(acol, 0.0, 0.0, 0.0);
        d = sumambient(acol, r, rdepth,
                        &atrunk, thescene.cuorg, thescene.cusize);
        if (d > FTINY)
                scalecolor(acol, 1.0/d);
        else {
                d = makeambient(acol, r, rdepth++);
                rdepth--;
        }
        if (d > FTINY)
                return;
dumbamb:                                        /* return global value */
        copycolor(acol, ambval);
}


double
sumambient(acol, r, al, at, c0, s)      /* get interpolated ambient value */
COLOR  acol;
register RAY  *r;
int  al;
AMBTREE  *at;
FVECT  c0;
double  s;
{
        double  d, e1, e2, wt, wsum;
        COLOR  ct;
        FVECT  ck0;
        int  i;
        register int  j;
        register AMBVAL  *av;
                                        /* do this node */
        wsum = 0.0;
        for (av = at->alist; av != NULL; av = av->next) {
                /*
                 *  Ambient level test.
                 */
                if (av->lvl > al || av->weight < r->rweight-FTINY)
                        continue;
                /*
                 *  Ambient radius test.
                 */
                e1 = 0.0;
                for (j = 0; j < 3; j++) {
                        d = av->pos[j] - r->rop[j];
                        e1 += d * d;
                }
                e1 /= av->rad * av->rad;
                if (e1 > ambacc*ambacc*1.21)
                        continue;
                /*
                 *  Normal direction test.
                 */
                e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
                if (e2 < 0.0) e2 = 0.0;
                if (e1 + e2 > ambacc*ambacc*1.21)
                        continue;
                /*
                 *  Ray behind test.
                 */
                d = 0.0;
                for (j = 0; j < 3; j++)
                        d += (r->rop[j] - av->pos[j]) *
                                        (av->dir[j] + r->ron[j]);
                if (d*0.5 < -minarad*ambacc-.001)
                        continue;
                /*
                 *  Jittering final test reduces image artifacts.
                 */
                wt = sqrt(e1) + sqrt(e2);
                wt *= .9 + .2*urand(9015+samplendx);
                if (wt > ambacc)
                        continue;
                if (wt <= 1e-3)
                        wt = 1e3;
                else
                        wt = 1.0 / wt;
                wsum += wt;
                extambient(ct, av, r->rop, r->ron);
                scalecolor(ct, wt);
                addcolor(acol, ct);
        }
        if (at->kid == NULL)
                return(wsum);
                                        /* do children */
        s *= 0.5;
        for (i = 0; i < 8; i++) {
                for (j = 0; j < 3; j++) {
                        ck0[j] = c0[j];
                        if (1<<j & i)
                                ck0[j] += s;
                        if (r->rop[j] < ck0[j] - OCTSCALE*s)
                                break;
                        if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
                                break;
                }
                if (j == 3)
                        wsum += sumambient(acol, r, al, at->kid+i, ck0, s);
        }
        return(wsum);
}


double
makeambient(acol, r, al)        /* make a new ambient value */
COLOR  acol;
register RAY  *r;
int  al;
{
        AMBVAL  amb;
        FVECT   gp, gd;
                                                /* compute weight */
        amb.weight = pow(AVGREFL, (double)al);
        if (r->rweight < 0.2*amb.weight)        /* heuristic */
                amb.weight = r->rweight;
                                                /* compute ambient */
        amb.rad = doambient(acol, r, amb.weight, gp, gd);
        if (amb.rad == 0.0)
                return(0.0);
                                                /* store it */
        VCOPY(amb.pos, r->rop);
        VCOPY(amb.dir, r->ron);
        amb.lvl = al;
        copycolor(amb.val, acol);
        VCOPY(amb.gpos, gp);
        VCOPY(amb.gdir, gd);
                                                /* insert into tree */
        avsave(&amb);                           /* and save to file */
        return(amb.rad);
}


extambient(cr, ap, pv, nv)              /* extrapolate value at pv, nv */
COLOR  cr;
register AMBVAL  *ap;
FVECT  pv, nv;
{
        FVECT  v1, v2;
        register int  i;
        double  d;

        d = 1.0;                        /* zeroeth order */
                                        /* gradient due to translation */
        for (i = 0; i < 3; i++)
                d += ap->gpos[i]*(pv[i]-ap->pos[i]);
                                        /* gradient due to rotation */
        VCOPY(v1, ap->dir);
        fcross(v2, v1, nv);
        d += DOT(ap->gdir, v2);
        if (d <= 0.0) {
                setcolor(cr, 0.0, 0.0, 0.0);
                return;
        }
        copycolor(cr, ap->val);
        scalecolor(cr, d);
}


static
initambfile(creat)              /* initialize ambient file */
int  creat;
{
        extern char  *progname, *octname, VersionID[];

#ifdef MSDOS
        setmode(fileno(ambfp), O_BINARY);
#endif
        setbuf(ambfp, bmalloc(BUFSIZ));
        if (creat) {                    /* new file */
                fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
                                progname, colval(ambval,RED),
                                colval(ambval,GRN), colval(ambval,BLU),
                                ambounce, ambacc);
                fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
                                ambdiv, ambssamp, ambres,
                                octname==NULL ? "" : octname);
                fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
                fputformat(AMBFMT, ambfp);
                putc('\n', ambfp);
                putambmagic(ambfp);
        } else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp))
                error(USER, "bad ambient file");
        ambsync();
}


static
avsave(av)                              /* insert and save an ambient value */
AMBVAL  *av;
{
        static int  nunflshed = 0;

        avinsert(av, &atrunk, thescene.cuorg, thescene.cusize);
        if (ambfp == NULL)
                return;
        if (writambval(av, ambfp) < 0)
                goto writerr;
        if (++nunflshed >= AMBFLUSH) {
                if (ambsync() == EOF)
                        goto writerr;
                nunflshed = 0;
        }
        return;
writerr:
        error(SYSTEM, "error writing ambient file");
}


static
avinsert(aval, at, c0, s)               /* insert ambient value in a tree */
AMBVAL  *aval;
register AMBTREE  *at;
FVECT  c0;
double  s;
{
        FVECT  ck0;
        int  branch;
        register AMBVAL  *av;
        register int  i;

        if ((av = newambval()) == NULL)
                goto memerr;
        copystruct(av, aval);
        VCOPY(ck0, c0);
        while (s*(OCTSCALE/2) > av->rad*ambacc) {
                if (at->kid == NULL)
                        if ((at->kid = newambtree()) == NULL)
                                goto memerr;
                s *= 0.5;
                branch = 0;
                for (i = 0; i < 3; i++)
                        if (av->pos[i] > ck0[i] + s) {
                                ck0[i] += s;
                                branch |= 1 << i;
                        }
                at = at->kid + branch;
        }
        av->next = at->alist;
        at->alist = av;
        return;
memerr:
        error(SYSTEM, "out of memory in avinsert");
}


#ifdef  NIX

static
ambsync()                       /* flush ambient file */
{
        return(fflush(ambfp));
}

#else

static
ambsync()                       /* synchronize ambient file */
{
        static FILE  *ambinp = NULL;
        static long  lastpos = -1;
        struct flock  fls;
        long  flen;
        AMBVAL  avs;
        register int  n;
                                /* gain exclusive access */
        fls.l_type = F_WRLCK;
        fls.l_whence = 0;
        fls.l_start = 0L;
        fls.l_len = 0L;
        if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
                error(SYSTEM, "cannot lock ambient file");
        if (lastpos < 0)        /* initializing */
                goto syncend;
                                /* see if file has grown */
        if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
                error(SYSTEM, "cannot seek on ambient file");
        if (n = flen - lastpos) {               /* file has grown */
                if (ambinp == NULL) {
                        ambinp = fopen(ambfname, "r");
                        if (ambinp == NULL)
                                error(SYSTEM, "fopen failed in ambsync");
                }
                if (fseek(ambinp, lastpos, 0) < 0)
                        error(SYSTEM, "fseek failed in ambsync");
                while (n >= AMBVALSIZ) {        /* load contributed values */
                        readambval(&avs, ambinp);
                        avinsert(&avs,&atrunk,thescene.cuorg,thescene.cusize);
                        n -= AMBVALSIZ;
                }
                if (n)                          /* alignment */
                        lseek(fileno(ambfp), flen-n, 0);
        }
syncend:
        n = fflush(ambfp);                      /* calls write() at last */
        lastpos = lseek(fileno(ambfp), 0L, 1);
        fls.l_type = F_UNLCK;                   /* release file */
        fcntl(fileno(ambfp), F_SETLKW, &fls);
        return(n);
}

#endif
Revision:	2.15
Committed:	Wed Jan 20 10:48:23 1993 UTC (31 years, 3 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.14:	+22 -24 lines
Log Message:	modified ambsync() to work on forked processes sharing file pointers
#	User	Rev	Content
1	greg	2.15	/* Copyright (c) 1993 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* ambient.c - routines dealing with ambient (inter-reflected) component.
9			*/
10
11			#include "ray.h"
12
13			#include "octree.h"
14
15	greg	1.8	#include "otypes.h"
16
17	greg	1.14	#include "ambient.h"
18
19	greg	1.1	#include "random.h"
20
21	greg	2.12	#define OCTSCALE 0.5 /* ceil((valid rad.)/(cube size)) */
22	greg	1.1
23	greg	1.14	typedef struct ambtree {
24	greg	2.12	AMBVAL alist; / ambient value list */
25			struct ambtree kid; / 8 child nodes */
26	greg	1.14	} AMBTREE; /* ambient octree */
27
28	greg	1.1	extern CUBE thescene; /* contains space boundaries */
29
30	greg	2.12	#define MAXASET 511 /* maximum number of elements in ambient set */
31			OBJECT ambset[MAXASET+1]={0}; /* ambient include/exclude set */
32	greg	1.1
33	greg	2.12	double maxarad; /* maximum ambient radius */
34			double minarad; /* minimum ambient radius */
35	greg	1.1
36	greg	2.12	static AMBTREE atrunk; /* our ambient trunk node */
37	greg	1.1
38	greg	2.15	static char ambfname = NULL; / ambient file name */
39	greg	1.1	static FILE ambfp = NULL; / ambient file pointer */
40
41	greg	2.12	#define AMBFLUSH (BUFSIZ/AMBVALSIZ)
42	greg	2.6
43	greg	2.12	#define newambval() (AMBVAL *)bmalloc(sizeof(AMBVAL))
44	greg	1.1
45	greg	2.12	#define newambtree() (AMBTREE *)calloc(8, sizeof(AMBTREE))
46	greg	1.1
47	greg	2.7	extern long ftell(), lseek();
48	greg	2.10	static int initambfile(), avsave(), avinsert(), ambsync();
49	greg	1.1
50	greg	2.7
51	greg	2.3	setambres(ar) /* set ambient resolution */
52			int ar;
53			{
54			/* set min & max radii */
55			if (ar <= 0) {
56			minarad = 0.0;
57			maxarad = thescene.cusize / 2.0;
58			} else {
59			minarad = thescene.cusize / ar;
60			maxarad = 16.0 * minarad; /* heuristic */
61			if (maxarad > thescene.cusize / 2.0)
62			maxarad = thescene.cusize / 2.0;
63			}
64	greg	2.4	if (maxarad <= FTINY)
65			maxarad = .001;
66	greg	2.3	}
67
68
69	greg	1.1	setambient(afile) /* initialize calculation */
70			char *afile;
71			{
72	greg	2.9	long headlen;
73	greg	2.12	AMBVAL amb;
74	greg	2.3	/* init ambient limits */
75			setambres(ambres);
76			/* open ambient file */
77	greg	2.15	if ((ambfname = afile) != NULL)
78	greg	1.1	if ((ambfp = fopen(afile, "r+")) != NULL) {
79	greg	2.6	initambfile(0);
80	greg	2.9	headlen = ftell(ambfp);
81	greg	2.5	while (readambval(&amb, ambfp))
82	greg	1.1	avinsert(&amb, &atrunk, thescene.cuorg,
83			thescene.cusize);
84			/* align */
85	greg	2.9	fseek(ambfp, -((ftell(ambfp)-headlen)%AMBVALSIZ), 1);
86	greg	2.10	} else if ((ambfp = fopen(afile, "w+")) != NULL)
87	greg	2.6	initambfile(1);
88			else {
89	greg	1.1	sprintf(errmsg, "cannot open ambient file \"%s\"",
90			afile);
91			error(SYSTEM, errmsg);
92	greg	1.8	}
93			}
94
95
96			ambnotify(obj) /* record new modifier */
97	greg	2.12	OBJECT obj;
98	greg	1.8	{
99	greg	1.11	static int hitlimit = 0;
100	greg	2.12	register OBJREC *o = objptr(obj);
101	greg	1.8	register char **amblp;
102
103	greg	1.11	if (hitlimit \|\| !ismodifier(o->otype))
104	greg	1.8	return;
105			for (amblp = amblist; *amblp != NULL; amblp++)
106			if (!strcmp(o->oname, *amblp)) {
107	greg	1.11	if (ambset[0] >= MAXASET) {
108			error(WARNING, "too many modifiers in ambient list");
109			hitlimit++;
110			return; /* should this be fatal? */
111			}
112	greg	1.8	insertelem(ambset, obj);
113			return;
114	greg	1.1	}
115			}
116
117
118			ambient(acol, r) /* compute ambient component for ray */
119			COLOR acol;
120			register RAY *r;
121			{
122			static int rdepth = 0; /* ambient recursion */
123	greg	2.12	double d;
124	greg	1.1
125			if (ambdiv <= 0) /* no ambient calculation */
126			goto dumbamb;
127			/* check number of bounces */
128	greg	1.16	if (rdepth >= ambounce)
129	greg	1.1	goto dumbamb;
130			/* check ambient list */
131			if (ambincl != -1 && r->ro != NULL &&
132			ambincl != inset(ambset, r->ro->omod))
133			goto dumbamb;
134
135			if (ambacc <= FTINY) { /* no ambient storage */
136	greg	1.16	rdepth++;
137			d = doambient(acol, r, r->rweight, NULL, NULL);
138			rdepth--;
139			if (d == 0.0)
140	greg	1.1	goto dumbamb;
141	greg	1.16	return;
142	greg	1.1	}
143			/* get ambient value */
144			setcolor(acol, 0.0, 0.0, 0.0);
145	greg	1.16	d = sumambient(acol, r, rdepth,
146			&atrunk, thescene.cuorg, thescene.cusize);
147			if (d > FTINY)
148			scalecolor(acol, 1.0/d);
149			else {
150			d = makeambient(acol, r, rdepth++);
151			rdepth--;
152			}
153			if (d > FTINY)
154			return;
155	greg	1.1	dumbamb: /* return global value */
156			copycolor(acol, ambval);
157			}
158
159
160			double
161	greg	1.16	sumambient(acol, r, al, at, c0, s) /* get interpolated ambient value */
162	greg	1.1	COLOR acol;
163			register RAY *r;
164	greg	1.16	int al;
165	greg	2.12	AMBTREE *at;
166	greg	1.1	FVECT c0;
167	greg	2.12	double s;
168	greg	1.1	{
169	greg	2.12	double d, e1, e2, wt, wsum;
170	greg	1.1	COLOR ct;
171			FVECT ck0;
172			int i;
173			register int j;
174	greg	2.12	register AMBVAL *av;
175	greg	1.7	/* do this node */
176	greg	1.1	wsum = 0.0;
177			for (av = at->alist; av != NULL; av = av->next) {
178			/*
179	greg	1.16	* Ambient level test.
180	greg	1.1	*/
181	greg	1.16	if (av->lvl > al \|\| av->weight < r->rweight-FTINY)
182	greg	1.1	continue;
183			/*
184			* Ambient radius test.
185			*/
186			e1 = 0.0;
187			for (j = 0; j < 3; j++) {
188			d = av->pos[j] - r->rop[j];
189			e1 += d * d;
190			}
191			e1 /= av->rad * av->rad;
192			if (e1 > ambaccambacc1.21)
193			continue;
194			/*
195			* Normal direction test.
196			*/
197			e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
198			if (e2 < 0.0) e2 = 0.0;
199			if (e1 + e2 > ambaccambacc1.21)
200			continue;
201			/*
202			* Ray behind test.
203			*/
204			d = 0.0;
205			for (j = 0; j < 3; j++)
206			d += (r->rop[j] - av->pos[j]) *
207			(av->dir[j] + r->ron[j]);
208	greg	1.18	if (d0.5 < -minaradambacc-.001)
209	greg	1.1	continue;
210			/*
211			* Jittering final test reduces image artifacts.
212			*/
213			wt = sqrt(e1) + sqrt(e2);
214	greg	2.2	wt = .9 + .2urand(9015+samplendx);
215	greg	1.6	if (wt > ambacc)
216	greg	1.1	continue;
217			if (wt <= 1e-3)
218			wt = 1e3;
219			else
220			wt = 1.0 / wt;
221			wsum += wt;
222	greg	1.15	extambient(ct, av, r->rop, r->ron);
223	greg	1.1	scalecolor(ct, wt);
224			addcolor(acol, ct);
225	greg	1.7	}
226			if (at->kid == NULL)
227			return(wsum);
228			/* do children */
229			s *= 0.5;
230			for (i = 0; i < 8; i++) {
231			for (j = 0; j < 3; j++) {
232			ck0[j] = c0[j];
233			if (1<<j & i)
234			ck0[j] += s;
235			if (r->rop[j] < ck0[j] - OCTSCALE*s)
236			break;
237			if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
238			break;
239			}
240			if (j == 3)
241	greg	1.16	wsum += sumambient(acol, r, al, at->kid+i, ck0, s);
242	greg	1.1	}
243			return(wsum);
244			}
245
246
247			double
248	greg	1.16	makeambient(acol, r, al) /* make a new ambient value */
249	greg	1.1	COLOR acol;
250			register RAY *r;
251	greg	1.16	int al;
252	greg	1.1	{
253	greg	2.12	AMBVAL amb;
254	greg	1.14	FVECT gp, gd;
255	greg	1.16	/* compute weight */
256			amb.weight = pow(AVGREFL, (double)al);
257	greg	1.17	if (r->rweight < 0.2amb.weight) / heuristic */
258	greg	1.16	amb.weight = r->rweight;
259			/* compute ambient */
260			amb.rad = doambient(acol, r, amb.weight, gp, gd);
261	greg	1.1	if (amb.rad == 0.0)
262			return(0.0);
263			/* store it */
264			VCOPY(amb.pos, r->rop);
265			VCOPY(amb.dir, r->ron);
266	greg	1.16	amb.lvl = al;
267	greg	1.1	copycolor(amb.val, acol);
268	greg	1.14	VCOPY(amb.gpos, gp);
269			VCOPY(amb.gdir, gd);
270	greg	1.1	/* insert into tree */
271	greg	2.7	avsave(&amb); /* and save to file */
272	greg	1.1	return(amb.rad);
273	greg	1.15	}
274
275
276			extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
277			COLOR cr;
278	greg	2.12	register AMBVAL *ap;
279	greg	1.15	FVECT pv, nv;
280			{
281			FVECT v1, v2;
282			register int i;
283	greg	2.12	double d;
284	greg	1.15
285			d = 1.0; /* zeroeth order */
286			/* gradient due to translation */
287			for (i = 0; i < 3; i++)
288			d += ap->gpos[i]*(pv[i]-ap->pos[i]);
289			/* gradient due to rotation */
290			VCOPY(v1, ap->dir);
291			fcross(v2, v1, nv);
292			d += DOT(ap->gdir, v2);
293			if (d <= 0.0) {
294			setcolor(cr, 0.0, 0.0, 0.0);
295			return;
296			}
297			copycolor(cr, ap->val);
298			scalecolor(cr, d);
299	greg	1.1	}
300
301
302			static
303	greg	2.9	initambfile(creat) /* initialize ambient file */
304			int creat;
305			{
306			extern char progname, octname, VersionID[];
307
308	greg	2.12	#ifdef MSDOS
309			setmode(fileno(ambfp), O_BINARY);
310			#endif
311	greg	2.9	setbuf(ambfp, bmalloc(BUFSIZ));
312			if (creat) { /* new file */
313			fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
314			progname, colval(ambval,RED),
315			colval(ambval,GRN), colval(ambval,BLU),
316			ambounce, ambacc);
317			fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
318			ambdiv, ambssamp, ambres,
319			octname==NULL ? "" : octname);
320			fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
321			fputformat(AMBFMT, ambfp);
322			putc('\n', ambfp);
323			putambmagic(ambfp);
324	greg	2.10	} else if (checkheader(ambfp, AMBFMT, NULL) < 0 \|\| !hasambmagic(ambfp))
325			error(USER, "bad ambient file");
326	greg	2.15	ambsync();
327	greg	2.9	}
328
329
330			static
331	greg	2.7	avsave(av) /* insert and save an ambient value */
332	greg	2.12	AMBVAL *av;
333	greg	1.1	{
334			static int nunflshed = 0;
335	greg	2.6
336	greg	2.7	avinsert(av, &atrunk, thescene.cuorg, thescene.cusize);
337	greg	1.1	if (ambfp == NULL)
338			return;
339	greg	2.5	if (writambval(av, ambfp) < 0)
340	greg	1.1	goto writerr;
341			if (++nunflshed >= AMBFLUSH) {
342	greg	2.7	if (ambsync() == EOF)
343	greg	1.1	goto writerr;
344			nunflshed = 0;
345			}
346			return;
347			writerr:
348			error(SYSTEM, "error writing ambient file");
349			}
350
351
352			static
353			avinsert(aval, at, c0, s) /* insert ambient value in a tree */
354	greg	2.12	AMBVAL *aval;
355	greg	1.1	register AMBTREE *at;
356			FVECT c0;
357	greg	2.12	double s;
358	greg	1.1	{
359			FVECT ck0;
360			int branch;
361	greg	2.12	register AMBVAL *av;
362	greg	1.1	register int i;
363
364			if ((av = newambval()) == NULL)
365			goto memerr;
366	greg	1.9	copystruct(av, aval);
367	greg	1.1	VCOPY(ck0, c0);
368			while (s(OCTSCALE/2) > av->radambacc) {
369			if (at->kid == NULL)
370			if ((at->kid = newambtree()) == NULL)
371			goto memerr;
372			s *= 0.5;
373			branch = 0;
374			for (i = 0; i < 3; i++)
375			if (av->pos[i] > ck0[i] + s) {
376			ck0[i] += s;
377			branch \|= 1 << i;
378			}
379			at = at->kid + branch;
380			}
381			av->next = at->alist;
382			at->alist = av;
383			return;
384			memerr:
385			error(SYSTEM, "out of memory in avinsert");
386	greg	2.7	}
387
388
389	greg	2.12	#ifdef NIX
390	greg	2.10
391			static
392			ambsync() /* flush ambient file */
393			{
394			return(fflush(ambfp));
395			}
396
397			#else
398
399	greg	2.7	static
400			ambsync() /* synchronize ambient file */
401			{
402			static FILE *ambinp = NULL;
403	greg	2.15	static long lastpos = -1;
404	greg	2.7	struct flock fls;
405	greg	2.15	long flen;
406	greg	2.12	AMBVAL avs;
407	greg	2.7	register int n;
408			/* gain exclusive access */
409			fls.l_type = F_WRLCK;
410			fls.l_whence = 0;
411			fls.l_start = 0L;
412			fls.l_len = 0L;
413			if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
414			error(SYSTEM, "cannot lock ambient file");
415	greg	2.15	if (lastpos < 0) /* initializing */
416			goto syncend;
417	greg	2.7	/* see if file has grown */
418	greg	2.15	if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
419			error(SYSTEM, "cannot seek on ambient file");
420			if (n = flen - lastpos) { /* file has grown */
421			if (ambinp == NULL) {
422			ambinp = fopen(ambfname, "r");
423	greg	2.14	if (ambinp == NULL)
424	greg	2.15	error(SYSTEM, "fopen failed in ambsync");
425	greg	2.14	}
426	greg	2.15	if (fseek(ambinp, lastpos, 0) < 0)
427			error(SYSTEM, "fseek failed in ambsync");
428			while (n >= AMBVALSIZ) { /* load contributed values */
429	greg	2.7	readambval(&avs, ambinp);
430			avinsert(&avs,&atrunk,thescene.cuorg,thescene.cusize);
431	greg	2.15	n -= AMBVALSIZ;
432			}
433			if (n) /* alignment */
434	greg	2.10	lseek(fileno(ambfp), flen-n, 0);
435	greg	2.7	}
436	greg	2.15	syncend:
437	greg	2.7	n = fflush(ambfp); /* calls write() at last */
438	greg	2.15	lastpos = lseek(fileno(ambfp), 0L, 1);
439	greg	2.7	fls.l_type = F_UNLCK; /* release file */
440			fcntl(fileno(ambfp), F_SETLKW, &fls);
441			return(n);
442	greg	1.1	}
443	greg	2.10
444			#endif