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();
#ifdef  F_SETLKW
static  aflock();
#endif


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);
        if (afile == NULL)
                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);
                                                /* 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  F_SETLKW
        aflock(creat ? F_WRLCK : F_RDLCK);
#endif
#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

static
aflock(typ)                     /* lock/unlock ambient file */
int  typ;
{
        static struct flock  fls;       /* static so initialized to zeroes */

        fls.l_type = typ;
        if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
                error(SYSTEM, "cannot (un)lock ambient file");
}


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

        if (nunflshed == 0)
                return(0);
        if (lastpos < 0)        /* initializing (locked in initambfile) */
                goto syncend;
                                /* gain exclusive access */
        aflock(F_WRLCK);
                                /* 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);
        aflock(F_UNLCK);                        /* release file */
        nunflshed = 0;
        return(n);
}

#else

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

#endif
Revision:	2.19
Committed:	Wed Aug 4 14:22:11 1993 UTC (30 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.18:	+39 -29 lines
Log Message:	fixed bug due to NFS sloppiness on writing files w/o lock manager
#	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	2.19	#ifdef F_SETLKW
50			static aflock();
51			#endif
52	greg	1.1
53	greg	2.7
54	greg	2.3	setambres(ar) /* set ambient resolution */
55			int ar;
56			{
57			/* set min & max radii */
58			if (ar <= 0) {
59			minarad = 0.0;
60			maxarad = thescene.cusize / 2.0;
61			} else {
62			minarad = thescene.cusize / ar;
63			maxarad = 16.0 * minarad; /* heuristic */
64			if (maxarad > thescene.cusize / 2.0)
65			maxarad = thescene.cusize / 2.0;
66			}
67	greg	2.4	if (maxarad <= FTINY)
68			maxarad = .001;
69	greg	2.3	}
70
71
72	greg	1.1	setambient(afile) /* initialize calculation */
73			char *afile;
74			{
75	greg	2.9	long headlen;
76	greg	2.12	AMBVAL amb;
77	greg	2.3	/* init ambient limits */
78			setambres(ambres);
79	greg	2.19	if (afile == NULL)
80			return;
81	greg	2.3	/* open ambient file */
82	greg	2.19	if ((ambfp = fopen(afile, "r+")) != NULL) {
83			initambfile(0);
84			headlen = ftell(ambfp);
85			while (readambval(&amb, ambfp))
86			avinsert(&amb, &atrunk, thescene.cuorg,
87			thescene.cusize);
88			/* align */
89			fseek(ambfp, -((ftell(ambfp)-headlen)%AMBVALSIZ), 1);
90			} else if ((ambfp = fopen(afile, "w+")) != NULL)
91			initambfile(1);
92			else {
93			sprintf(errmsg, "cannot open ambient file \"%s\"", afile);
94			error(SYSTEM, errmsg);
95	greg	2.16	}
96	greg	2.19	nunflshed++; /* lie */
97			ambsync();
98	greg	1.8	}
99
100
101			ambnotify(obj) /* record new modifier */
102	greg	2.12	OBJECT obj;
103	greg	1.8	{
104	greg	1.11	static int hitlimit = 0;
105	greg	2.12	register OBJREC *o = objptr(obj);
106	greg	1.8	register char **amblp;
107
108	greg	1.11	if (hitlimit \|\| !ismodifier(o->otype))
109	greg	1.8	return;
110			for (amblp = amblist; *amblp != NULL; amblp++)
111			if (!strcmp(o->oname, *amblp)) {
112	greg	1.11	if (ambset[0] >= MAXASET) {
113			error(WARNING, "too many modifiers in ambient list");
114			hitlimit++;
115			return; /* should this be fatal? */
116			}
117	greg	1.8	insertelem(ambset, obj);
118			return;
119	greg	1.1	}
120			}
121
122
123			ambient(acol, r) /* compute ambient component for ray */
124			COLOR acol;
125			register RAY *r;
126			{
127			static int rdepth = 0; /* ambient recursion */
128	greg	2.12	double d;
129	greg	1.1
130			if (ambdiv <= 0) /* no ambient calculation */
131			goto dumbamb;
132			/* check number of bounces */
133	greg	1.16	if (rdepth >= ambounce)
134	greg	1.1	goto dumbamb;
135			/* check ambient list */
136			if (ambincl != -1 && r->ro != NULL &&
137			ambincl != inset(ambset, r->ro->omod))
138			goto dumbamb;
139
140			if (ambacc <= FTINY) { /* no ambient storage */
141	greg	1.16	rdepth++;
142			d = doambient(acol, r, r->rweight, NULL, NULL);
143			rdepth--;
144			if (d == 0.0)
145	greg	1.1	goto dumbamb;
146	greg	1.16	return;
147	greg	1.1	}
148			/* get ambient value */
149			setcolor(acol, 0.0, 0.0, 0.0);
150	greg	1.16	d = sumambient(acol, r, rdepth,
151			&atrunk, thescene.cuorg, thescene.cusize);
152			if (d > FTINY)
153			scalecolor(acol, 1.0/d);
154			else {
155			d = makeambient(acol, r, rdepth++);
156			rdepth--;
157			}
158			if (d > FTINY)
159			return;
160	greg	1.1	dumbamb: /* return global value */
161			copycolor(acol, ambval);
162			}
163
164
165			double
166	greg	1.16	sumambient(acol, r, al, at, c0, s) /* get interpolated ambient value */
167	greg	1.1	COLOR acol;
168			register RAY *r;
169	greg	1.16	int al;
170	greg	2.12	AMBTREE *at;
171	greg	1.1	FVECT c0;
172	greg	2.12	double s;
173	greg	1.1	{
174	greg	2.12	double d, e1, e2, wt, wsum;
175	greg	1.1	COLOR ct;
176			FVECT ck0;
177			int i;
178			register int j;
179	greg	2.12	register AMBVAL *av;
180	greg	1.7	/* do this node */
181	greg	1.1	wsum = 0.0;
182			for (av = at->alist; av != NULL; av = av->next) {
183			/*
184	greg	1.16	* Ambient level test.
185	greg	1.1	*/
186	greg	1.16	if (av->lvl > al \|\| av->weight < r->rweight-FTINY)
187	greg	1.1	continue;
188			/*
189			* Ambient radius test.
190			*/
191			e1 = 0.0;
192			for (j = 0; j < 3; j++) {
193			d = av->pos[j] - r->rop[j];
194			e1 += d * d;
195			}
196			e1 /= av->rad * av->rad;
197			if (e1 > ambaccambacc1.21)
198			continue;
199			/*
200			* Normal direction test.
201			*/
202			e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
203			if (e2 < 0.0) e2 = 0.0;
204			if (e1 + e2 > ambaccambacc1.21)
205			continue;
206			/*
207			* Ray behind test.
208			*/
209			d = 0.0;
210			for (j = 0; j < 3; j++)
211			d += (r->rop[j] - av->pos[j]) *
212			(av->dir[j] + r->ron[j]);
213	greg	1.18	if (d0.5 < -minaradambacc-.001)
214	greg	1.1	continue;
215			/*
216			* Jittering final test reduces image artifacts.
217			*/
218			wt = sqrt(e1) + sqrt(e2);
219	greg	2.2	wt = .9 + .2urand(9015+samplendx);
220	greg	1.6	if (wt > ambacc)
221	greg	1.1	continue;
222			if (wt <= 1e-3)
223			wt = 1e3;
224			else
225			wt = 1.0 / wt;
226			wsum += wt;
227	greg	1.15	extambient(ct, av, r->rop, r->ron);
228	greg	1.1	scalecolor(ct, wt);
229			addcolor(acol, ct);
230	greg	1.7	}
231			if (at->kid == NULL)
232			return(wsum);
233			/* do children */
234			s *= 0.5;
235			for (i = 0; i < 8; i++) {
236			for (j = 0; j < 3; j++) {
237			ck0[j] = c0[j];
238			if (1<<j & i)
239			ck0[j] += s;
240			if (r->rop[j] < ck0[j] - OCTSCALE*s)
241			break;
242			if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
243			break;
244			}
245			if (j == 3)
246	greg	1.16	wsum += sumambient(acol, r, al, at->kid+i, ck0, s);
247	greg	1.1	}
248			return(wsum);
249			}
250
251
252			double
253	greg	1.16	makeambient(acol, r, al) /* make a new ambient value */
254	greg	1.1	COLOR acol;
255			register RAY *r;
256	greg	1.16	int al;
257	greg	1.1	{
258	greg	2.12	AMBVAL amb;
259	greg	1.14	FVECT gp, gd;
260	greg	1.16	/* compute weight */
261			amb.weight = pow(AVGREFL, (double)al);
262	greg	1.17	if (r->rweight < 0.2amb.weight) / heuristic */
263	greg	1.16	amb.weight = r->rweight;
264			/* compute ambient */
265			amb.rad = doambient(acol, r, amb.weight, gp, gd);
266	greg	1.1	if (amb.rad == 0.0)
267			return(0.0);
268			/* store it */
269			VCOPY(amb.pos, r->rop);
270			VCOPY(amb.dir, r->ron);
271	greg	1.16	amb.lvl = al;
272	greg	1.1	copycolor(amb.val, acol);
273	greg	1.14	VCOPY(amb.gpos, gp);
274			VCOPY(amb.gdir, gd);
275	greg	1.1	/* insert into tree */
276	greg	2.7	avsave(&amb); /* and save to file */
277	greg	1.1	return(amb.rad);
278	greg	1.15	}
279
280
281			extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
282			COLOR cr;
283	greg	2.12	register AMBVAL *ap;
284	greg	1.15	FVECT pv, nv;
285			{
286			FVECT v1, v2;
287			register int i;
288	greg	2.12	double d;
289	greg	1.15
290			d = 1.0; /* zeroeth order */
291			/* gradient due to translation */
292			for (i = 0; i < 3; i++)
293			d += ap->gpos[i]*(pv[i]-ap->pos[i]);
294			/* gradient due to rotation */
295			VCOPY(v1, ap->dir);
296			fcross(v2, v1, nv);
297			d += DOT(ap->gdir, v2);
298			if (d <= 0.0) {
299			setcolor(cr, 0.0, 0.0, 0.0);
300			return;
301			}
302			copycolor(cr, ap->val);
303			scalecolor(cr, d);
304	greg	1.1	}
305
306
307			static
308	greg	2.9	initambfile(creat) /* initialize ambient file */
309			int creat;
310			{
311			extern char progname, octname, VersionID[];
312
313	greg	2.19	#ifdef F_SETLKW
314			aflock(creat ? F_WRLCK : F_RDLCK);
315			#endif
316	greg	2.12	#ifdef MSDOS
317			setmode(fileno(ambfp), O_BINARY);
318			#endif
319	greg	2.9	setbuf(ambfp, bmalloc(BUFSIZ));
320			if (creat) { /* new file */
321			fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
322			progname, colval(ambval,RED),
323			colval(ambval,GRN), colval(ambval,BLU),
324			ambounce, ambacc);
325			fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
326			ambdiv, ambssamp, ambres,
327			octname==NULL ? "" : octname);
328			fprintf(ambfp, "SOFTWARE= %s\n", VersionID);
329			fputformat(AMBFMT, ambfp);
330			putc('\n', ambfp);
331			putambmagic(ambfp);
332	greg	2.17	} else if (checkheader(ambfp, AMBFMT, NULL) < 0 \|\| !hasambmagic(ambfp))
333			error(USER, "bad ambient file");
334	greg	2.9	}
335
336
337			static
338	greg	2.7	avsave(av) /* insert and save an ambient value */
339	greg	2.12	AMBVAL *av;
340	greg	1.1	{
341	greg	2.7	avinsert(av, &atrunk, thescene.cuorg, thescene.cusize);
342	greg	1.1	if (ambfp == NULL)
343			return;
344	greg	2.5	if (writambval(av, ambfp) < 0)
345	greg	1.1	goto writerr;
346	greg	2.16	if (++nunflshed >= AMBFLUSH)
347	greg	2.7	if (ambsync() == EOF)
348	greg	1.1	goto writerr;
349			return;
350			writerr:
351	greg	2.17	error(SYSTEM, "error writing ambient file");
352	greg	1.1	}
353
354
355			static
356			avinsert(aval, at, c0, s) /* insert ambient value in a tree */
357	greg	2.12	AMBVAL *aval;
358	greg	1.1	register AMBTREE *at;
359			FVECT c0;
360	greg	2.12	double s;
361	greg	1.1	{
362			FVECT ck0;
363			int branch;
364	greg	2.12	register AMBVAL *av;
365	greg	1.1	register int i;
366
367			if ((av = newambval()) == NULL)
368			goto memerr;
369	greg	1.9	copystruct(av, aval);
370	greg	1.1	VCOPY(ck0, c0);
371			while (s(OCTSCALE/2) > av->radambacc) {
372			if (at->kid == NULL)
373			if ((at->kid = newambtree()) == NULL)
374			goto memerr;
375			s *= 0.5;
376			branch = 0;
377			for (i = 0; i < 3; i++)
378			if (av->pos[i] > ck0[i] + s) {
379			ck0[i] += s;
380			branch \|= 1 << i;
381			}
382			at = at->kid + branch;
383			}
384			av->next = at->alist;
385			at->alist = av;
386			return;
387			memerr:
388			error(SYSTEM, "out of memory in avinsert");
389	greg	2.7	}
390
391
392	greg	2.18	#ifdef F_SETLKW
393	greg	2.10
394	greg	2.19	static
395			aflock(typ) /* lock/unlock ambient file */
396			int typ;
397			{
398			static struct flock fls; /* static so initialized to zeroes */
399
400			fls.l_type = typ;
401			if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0)
402			error(SYSTEM, "cannot (un)lock ambient file");
403			}
404
405
406	greg	2.16	int
407	greg	2.7	ambsync() /* synchronize ambient file */
408			{
409			static FILE *ambinp = NULL;
410	greg	2.15	static long lastpos = -1;
411			long flen;
412	greg	2.12	AMBVAL avs;
413	greg	2.7	register int n;
414	greg	2.16
415			if (nunflshed == 0)
416			return(0);
417	greg	2.19	if (lastpos < 0) /* initializing (locked in initambfile) */
418			goto syncend;
419	greg	2.7	/* gain exclusive access */
420	greg	2.19	aflock(F_WRLCK);
421	greg	2.7	/* see if file has grown */
422	greg	2.15	if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0)
423			error(SYSTEM, "cannot seek on ambient file");
424			if (n = flen - lastpos) { /* file has grown */
425	greg	2.17	if (ambinp == NULL) { /* use duplicate filedes */
426			ambinp = fdopen(dup(fileno(ambfp)), "r");
427	greg	2.14	if (ambinp == NULL)
428	greg	2.17	error(SYSTEM, "fdopen failed in ambsync");
429	greg	2.14	}
430	greg	2.15	if (fseek(ambinp, lastpos, 0) < 0)
431			error(SYSTEM, "fseek failed in ambsync");
432			while (n >= AMBVALSIZ) { /* load contributed values */
433	greg	2.7	readambval(&avs, ambinp);
434			avinsert(&avs,&atrunk,thescene.cuorg,thescene.cusize);
435	greg	2.15	n -= AMBVALSIZ;
436			}
437			if (n) /* alignment */
438	greg	2.10	lseek(fileno(ambfp), flen-n, 0);
439	greg	2.7	}
440	greg	2.15	syncend:
441	greg	2.7	n = fflush(ambfp); /* calls write() at last */
442	greg	2.15	lastpos = lseek(fileno(ambfp), 0L, 1);
443	greg	2.19	aflock(F_UNLCK); /* release file */
444	greg	2.16	nunflshed = 0;
445	greg	2.7	return(n);
446	greg	2.18	}
447
448			#else
449
450			int
451			ambsync() /* flush ambient file */
452			{
453			if (nunflshed == 0)
454			return(0);
455			nunflshed = 0;
456			return(fflush(ambfp));
457	greg	1.1	}
458	greg	2.10
459			#endif