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 FILE  *ambfp = NULL;     /* ambient file pointer */
static int  nunflshed = 0;      /* number of unflushed ambient values */

#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();


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 (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);
                }
                nunflshed++;    /* lie */
                ambsync();
        }
}


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");
}


static
avsave(av)                              /* insert and save an ambient value */
AMBVAL  *av;
{
        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;
        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  F_SETLKW

int
ambsync()                       /* synchronize ambient file */
{
        static FILE  *ambinp = NULL;
        static long  lastpos = -1;
        struct flock  fls;
        long  flen;
        AMBVAL  avs;
        register int  n;

        if (nunflshed == 0)
                return(0);
                                /* 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) {           /* use duplicate filedes */
                        ambinp = fdopen(dup(fileno(ambfp)), "r");
                        if (ambinp == NULL)
                                error(SYSTEM, "fdopen 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);
        nunflshed = 0;
        return(n);
}

#else

int
ambsync()                       /* flush ambient file */
{
        if (nunflshed == 0)
                return(0);
        nunflshed = 0;
        return(fflush(ambfp));
}

#endif
Revision:	2.18
Committed:	Fri Jan 29 12:02:23 1993 UTC (32 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.17:	+12 -12 lines
Log Message:	made parallel operations conditional on F_SETLKW
#	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			static FILE ambfp = NULL; / ambient file pointer */
39	greg	2.16	static int nunflshed = 0; /* number of unflushed ambient values */
40	greg	1.1
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	2.16	static int initambfile(), avsave(), avinsert();
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	2.17	if (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	greg	2.16	nunflshed++; /* lie */
94			ambsync();
95			}
96	greg	1.8	}
97
98
99			ambnotify(obj) /* record new modifier */
100	greg	2.12	OBJECT obj;
101	greg	1.8	{
102	greg	1.11	static int hitlimit = 0;
103	greg	2.12	register OBJREC *o = objptr(obj);
104	greg	1.8	register char **amblp;
105
106	greg	1.11	if (hitlimit \|\| !ismodifier(o->otype))
107	greg	1.8	return;
108			for (amblp = amblist; *amblp != NULL; amblp++)
109			if (!strcmp(o->oname, *amblp)) {
110	greg	1.11	if (ambset[0] >= MAXASET) {
111			error(WARNING, "too many modifiers in ambient list");
112			hitlimit++;
113			return; /* should this be fatal? */
114			}
115	greg	1.8	insertelem(ambset, obj);
116			return;
117	greg	1.1	}
118			}
119
120
121			ambient(acol, r) /* compute ambient component for ray */
122			COLOR acol;
123			register RAY *r;
124			{
125			static int rdepth = 0; /* ambient recursion */
126	greg	2.12	double d;
127	greg	1.1
128			if (ambdiv <= 0) /* no ambient calculation */
129			goto dumbamb;
130			/* check number of bounces */
131	greg	1.16	if (rdepth >= ambounce)
132	greg	1.1	goto dumbamb;
133			/* check ambient list */
134			if (ambincl != -1 && r->ro != NULL &&
135			ambincl != inset(ambset, r->ro->omod))
136			goto dumbamb;
137
138			if (ambacc <= FTINY) { /* no ambient storage */
139	greg	1.16	rdepth++;
140			d = doambient(acol, r, r->rweight, NULL, NULL);
141			rdepth--;
142			if (d == 0.0)
143	greg	1.1	goto dumbamb;
144	greg	1.16	return;
145	greg	1.1	}
146			/* get ambient value */
147			setcolor(acol, 0.0, 0.0, 0.0);
148	greg	1.16	d = sumambient(acol, r, rdepth,
149			&atrunk, thescene.cuorg, thescene.cusize);
150			if (d > FTINY)
151			scalecolor(acol, 1.0/d);
152			else {
153			d = makeambient(acol, r, rdepth++);
154			rdepth--;
155			}
156			if (d > FTINY)
157			return;
158	greg	1.1	dumbamb: /* return global value */
159			copycolor(acol, ambval);
160			}
161
162
163			double
164	greg	1.16	sumambient(acol, r, al, at, c0, s) /* get interpolated ambient value */
165	greg	1.1	COLOR acol;
166			register RAY *r;
167	greg	1.16	int al;
168	greg	2.12	AMBTREE *at;
169	greg	1.1	FVECT c0;
170	greg	2.12	double s;
171	greg	1.1	{
172	greg	2.12	double d, e1, e2, wt, wsum;
173	greg	1.1	COLOR ct;
174			FVECT ck0;
175			int i;
176			register int j;
177	greg	2.12	register AMBVAL *av;
178	greg	1.7	/* do this node */
179	greg	1.1	wsum = 0.0;
180			for (av = at->alist; av != NULL; av = av->next) {
181			/*
182	greg	1.16	* Ambient level test.
183	greg	1.1	*/
184	greg	1.16	if (av->lvl > al \|\| av->weight < r->rweight-FTINY)
185	greg	1.1	continue;
186			/*
187			* Ambient radius test.
188			*/
189			e1 = 0.0;
190			for (j = 0; j < 3; j++) {
191			d = av->pos[j] - r->rop[j];
192			e1 += d * d;
193			}
194			e1 /= av->rad * av->rad;
195			if (e1 > ambaccambacc1.21)
196			continue;
197			/*
198			* Normal direction test.
199			*/
200			e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
201			if (e2 < 0.0) e2 = 0.0;
202			if (e1 + e2 > ambaccambacc1.21)
203			continue;
204			/*
205			* Ray behind test.
206			*/
207			d = 0.0;
208			for (j = 0; j < 3; j++)
209			d += (r->rop[j] - av->pos[j]) *
210			(av->dir[j] + r->ron[j]);
211	greg	1.18	if (d0.5 < -minaradambacc-.001)
212	greg	1.1	continue;
213			/*
214			* Jittering final test reduces image artifacts.
215			*/
216			wt = sqrt(e1) + sqrt(e2);
217	greg	2.2	wt = .9 + .2urand(9015+samplendx);
218	greg	1.6	if (wt > ambacc)
219	greg	1.1	continue;
220			if (wt <= 1e-3)
221			wt = 1e3;
222			else
223			wt = 1.0 / wt;
224			wsum += wt;
225	greg	1.15	extambient(ct, av, r->rop, r->ron);
226	greg	1.1	scalecolor(ct, wt);
227			addcolor(acol, ct);
228	greg	1.7	}
229			if (at->kid == NULL)
230			return(wsum);
231			/* do children */
232			s *= 0.5;
233			for (i = 0; i < 8; i++) {
234			for (j = 0; j < 3; j++) {
235			ck0[j] = c0[j];
236			if (1<<j & i)
237			ck0[j] += s;
238			if (r->rop[j] < ck0[j] - OCTSCALE*s)
239			break;
240			if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
241			break;
242			}
243			if (j == 3)
244	greg	1.16	wsum += sumambient(acol, r, al, at->kid+i, ck0, s);
245	greg	1.1	}
246			return(wsum);
247			}
248
249
250			double
251	greg	1.16	makeambient(acol, r, al) /* make a new ambient value */
252	greg	1.1	COLOR acol;
253			register RAY *r;
254	greg	1.16	int al;
255	greg	1.1	{
256	greg	2.12	AMBVAL amb;
257	greg	1.14	FVECT gp, gd;
258	greg	1.16	/* compute weight */
259			amb.weight = pow(AVGREFL, (double)al);
260	greg	1.17	if (r->rweight < 0.2amb.weight) / heuristic */
261	greg	1.16	amb.weight = r->rweight;
262			/* compute ambient */
263			amb.rad = doambient(acol, r, amb.weight, gp, gd);
264	greg	1.1	if (amb.rad == 0.0)
265			return(0.0);
266			/* store it */
267			VCOPY(amb.pos, r->rop);
268			VCOPY(amb.dir, r->ron);
269	greg	1.16	amb.lvl = al;
270	greg	1.1	copycolor(amb.val, acol);
271	greg	1.14	VCOPY(amb.gpos, gp);
272			VCOPY(amb.gdir, gd);
273	greg	1.1	/* insert into tree */
274	greg	2.7	avsave(&amb); /* and save to file */
275	greg	1.1	return(amb.rad);
276	greg	1.15	}
277
278
279			extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
280			COLOR cr;
281	greg	2.12	register AMBVAL *ap;
282	greg	1.15	FVECT pv, nv;
283			{
284			FVECT v1, v2;
285			register int i;
286	greg	2.12	double d;
287	greg	1.15
288			d = 1.0; /* zeroeth order */
289			/* gradient due to translation */
290			for (i = 0; i < 3; i++)
291			d += ap->gpos[i]*(pv[i]-ap->pos[i]);
292			/* gradient due to rotation */
293			VCOPY(v1, ap->dir);
294			fcross(v2, v1, nv);
295			d += DOT(ap->gdir, v2);
296			if (d <= 0.0) {
297			setcolor(cr, 0.0, 0.0, 0.0);
298			return;
299			}
300			copycolor(cr, ap->val);
301			scalecolor(cr, d);
302	greg	1.1	}
303
304
305			static
306	greg	2.9	initambfile(creat) /* initialize ambient file */
307			int creat;
308			{
309			extern char progname, octname, VersionID[];
310
311	greg	2.12	#ifdef MSDOS
312			setmode(fileno(ambfp), O_BINARY);
313			#endif
314	greg	2.9	setbuf(ambfp, bmalloc(BUFSIZ));
315			if (creat) { /* new file */
316			fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
317			progname, colval(ambval,RED),
318			colval(ambval,GRN), colval(ambval,BLU),
319			ambounce, ambacc);
320			fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
321			ambdiv, ambssamp, ambres,
322			octname==NULL ? "" : octname);
323			fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
324			fputformat(AMBFMT, ambfp);
325			putc('\n', ambfp);
326			putambmagic(ambfp);
327	greg	2.17	} else if (checkheader(ambfp, AMBFMT, NULL) < 0 \|\| !hasambmagic(ambfp))
328			error(USER, "bad ambient file");
329	greg	2.9	}
330
331
332			static
333	greg	2.7	avsave(av) /* insert and save an ambient value */
334	greg	2.12	AMBVAL *av;
335	greg	1.1	{
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	greg	2.16	if (++nunflshed >= AMBFLUSH)
342	greg	2.7	if (ambsync() == EOF)
343	greg	1.1	goto writerr;
344			return;
345			writerr:
346	greg	2.17	error(SYSTEM, "error writing ambient file");
347	greg	1.1	}
348
349
350			static
351			avinsert(aval, at, c0, s) /* insert ambient value in a tree */
352	greg	2.12	AMBVAL *aval;
353	greg	1.1	register AMBTREE *at;
354			FVECT c0;
355	greg	2.12	double s;
356	greg	1.1	{
357			FVECT ck0;
358			int branch;
359	greg	2.12	register AMBVAL *av;
360	greg	1.1	register int i;
361
362			if ((av = newambval()) == NULL)
363			goto memerr;
364	greg	1.9	copystruct(av, aval);
365	greg	1.1	VCOPY(ck0, c0);
366			while (s(OCTSCALE/2) > av->radambacc) {
367			if (at->kid == NULL)
368			if ((at->kid = newambtree()) == NULL)
369			goto memerr;
370			s *= 0.5;
371			branch = 0;
372			for (i = 0; i < 3; i++)
373			if (av->pos[i] > ck0[i] + s) {
374			ck0[i] += s;
375			branch \|= 1 << i;
376			}
377			at = at->kid + branch;
378			}
379			av->next = at->alist;
380			at->alist = av;
381			return;
382			memerr:
383			error(SYSTEM, "out of memory in avinsert");
384	greg	2.7	}
385
386
387	greg	2.18	#ifdef F_SETLKW
388	greg	2.10
389	greg	2.16	int
390	greg	2.7	ambsync() /* synchronize ambient file */
391			{
392			static FILE *ambinp = NULL;
393	greg	2.15	static long lastpos = -1;
394	greg	2.7	struct flock fls;
395	greg	2.15	long flen;
396	greg	2.12	AMBVAL avs;
397	greg	2.7	register int n;
398	greg	2.16
399			if (nunflshed == 0)
400			return(0);
401	greg	2.7	/* gain exclusive access */
402			fls.l_type = F_WRLCK;
403			fls.l_whence = 0;
404			fls.l_start = 0L;
405			fls.l_len = 0L;
406			if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
407			error(SYSTEM, "cannot lock ambient file");
408	greg	2.15	if (lastpos < 0) /* initializing */
409			goto syncend;
410	greg	2.7	/* see if file has grown */
411	greg	2.15	if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
412			error(SYSTEM, "cannot seek on ambient file");
413			if (n = flen - lastpos) { /* file has grown */
414	greg	2.17	if (ambinp == NULL) { /* use duplicate filedes */
415			ambinp = fdopen(dup(fileno(ambfp)), "r");
416	greg	2.14	if (ambinp == NULL)
417	greg	2.17	error(SYSTEM, "fdopen failed in ambsync");
418	greg	2.14	}
419	greg	2.15	if (fseek(ambinp, lastpos, 0) < 0)
420			error(SYSTEM, "fseek failed in ambsync");
421			while (n >= AMBVALSIZ) { /* load contributed values */
422	greg	2.7	readambval(&avs, ambinp);
423			avinsert(&avs,&atrunk,thescene.cuorg,thescene.cusize);
424	greg	2.15	n -= AMBVALSIZ;
425			}
426			if (n) /* alignment */
427	greg	2.10	lseek(fileno(ambfp), flen-n, 0);
428	greg	2.7	}
429	greg	2.15	syncend:
430	greg	2.7	n = fflush(ambfp); /* calls write() at last */
431	greg	2.15	lastpos = lseek(fileno(ambfp), 0L, 1);
432	greg	2.7	fls.l_type = F_UNLCK; /* release file */
433			fcntl(fileno(ambfp), F_SETLKW, &fls);
434	greg	2.16	nunflshed = 0;
435	greg	2.7	return(n);
436	greg	2.18	}
437
438			#else
439
440			int
441			ambsync() /* flush ambient file */
442			{
443			if (nunflshed == 0)
444			return(0);
445			nunflshed = 0;
446			return(fflush(ambfp));
447	greg	1.1	}
448	greg	2.10
449			#endif