src/rt/ambient.c

/* Copyright (c) 1991 Regents of the University of California */

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

/*
 *  ambient.c - routines dealing with ambient (inter-reflected) component.
 *
 *  The macro AMBFLUSH (if defined) is the number of ambient values
 *      to wait before flushing to the ambient file.
 *
 *     5/9/86
 */

#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  ambheadlen;         /* length of ambient file header */

#define  AMBFLUSH       (BUFSIZ/AMBVALSIZ)

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

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


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


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

        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);
                fputformat(AMBFMT, ambfp);
                putc('\n', ambfp);
                putambmagic(ambfp);
                fflush(ambfp);
        } else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp))
                error(USER, "ambient file format error");
        ambheadlen = ftell(ambfp);
}


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;
{
        extern double  sqrt();
        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 */
        avinsert(&amb, &atrunk, thescene.cuorg, thescene.cusize);
        avsave(&amb);                           /* write 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
avsave(av)                              /* save an ambient value */
AMBVAL  *av;
{
        static int  nunflshed = 0;

        if (ambfp == NULL)
                return;
        if (writambval(av, ambfp) < 0)
                goto writerr;
        if (++nunflshed >= AMBFLUSH) {
                if (fflush(ambfp) == 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");
}
Revision:	2.6
Committed:	Thu Jul 16 12:09:08 1992 UTC (31 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.5:	+34 -7 lines
Log Message:	added header and magic number to ambient value file
#	User	Rev	Content
1	greg	1.14	/* Copyright (c) 1991 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			* The macro AMBFLUSH (if defined) is the number of ambient values
11			* to wait before flushing to the ambient file.
12			*
13			* 5/9/86
14			*/
15
16			#include "ray.h"
17
18			#include "octree.h"
19
20	greg	1.8	#include "otypes.h"
21
22	greg	1.14	#include "ambient.h"
23
24	greg	1.1	#include "random.h"
25
26			#define OCTSCALE 0.5 /* ceil((valid rad.)/(cube size)) */
27
28	greg	1.14	typedef struct ambtree {
29			AMBVAL alist; / ambient value list */
30			struct ambtree kid; / 8 child nodes */
31			} AMBTREE; /* ambient octree */
32
33	greg	1.1	extern CUBE thescene; /* contains space boundaries */
34
35	greg	1.11	#define MAXASET 511 /* maximum number of elements in ambient set */
36			OBJECT ambset[MAXASET+1]={0}; /* ambient include/exclude set */
37	greg	1.1
38			double maxarad; /* maximum ambient radius */
39			double minarad; /* minimum ambient radius */
40
41			static AMBTREE atrunk; /* our ambient trunk node */
42
43			static FILE ambfp = NULL; / ambient file pointer */
44	greg	2.6	static int ambheadlen; /* length of ambient file header */
45	greg	1.1
46	greg	2.6	#define AMBFLUSH (BUFSIZ/AMBVALSIZ)
47
48	greg	1.1	#define newambval() (AMBVAL *)bmalloc(sizeof(AMBVAL))
49
50			#define newambtree() (AMBTREE *)calloc(8, sizeof(AMBTREE))
51
52
53	greg	2.3	setambres(ar) /* set ambient resolution */
54			int ar;
55			{
56			/* set min & max radii */
57			if (ar <= 0) {
58			minarad = 0.0;
59			maxarad = thescene.cusize / 2.0;
60			} else {
61			minarad = thescene.cusize / ar;
62			maxarad = 16.0 * minarad; /* heuristic */
63			if (maxarad > thescene.cusize / 2.0)
64			maxarad = thescene.cusize / 2.0;
65			}
66	greg	2.4	if (maxarad <= FTINY)
67			maxarad = .001;
68	greg	2.3	}
69
70
71	greg	1.1	setambient(afile) /* initialize calculation */
72			char *afile;
73			{
74	greg	2.6	extern long ftell();
75	greg	1.1	AMBVAL amb;
76	greg	2.3	/* init ambient limits */
77			setambres(ambres);
78			/* open ambient file */
79	greg	1.1	if (afile != NULL)
80			if ((ambfp = fopen(afile, "r+")) != NULL) {
81	greg	2.6	initambfile(0);
82	greg	2.5	while (readambval(&amb, ambfp))
83	greg	1.1	avinsert(&amb, &atrunk, thescene.cuorg,
84			thescene.cusize);
85			/* align */
86	greg	2.6	fseek(ambfp, -((ftell(ambfp)-ambheadlen)%AMBVALSIZ), 1);
87			} else if ((ambfp = fopen(afile, "w")) != NULL)
88			initambfile(1);
89			else {
90	greg	1.1	sprintf(errmsg, "cannot open ambient file \"%s\"",
91			afile);
92			error(SYSTEM, errmsg);
93	greg	1.8	}
94			}
95
96
97	greg	2.6	initambfile(creat) /* initialize ambient file */
98			int creat;
99			{
100			extern char progname, octname;
101
102			setbuf(ambfp, bmalloc(BUFSIZ));
103			if (creat) { /* new file */
104			fprintf(ambfp, "%s -av %g %g %g -ab %d -aa %g ",
105			progname, colval(ambval,RED),
106			colval(ambval,GRN), colval(ambval,BLU),
107			ambounce, ambacc);
108			fprintf(ambfp, "-ad %d -as %d -ar %d %s\n",
109			ambdiv, ambssamp, ambres,
110			octname==NULL ? "" : octname);
111			fputformat(AMBFMT, ambfp);
112			putc('\n', ambfp);
113			putambmagic(ambfp);
114			fflush(ambfp);
115			} else if (checkheader(ambfp, AMBFMT, NULL) < 0 \|\| !hasambmagic(ambfp))
116			error(USER, "ambient file format error");
117			ambheadlen = ftell(ambfp);
118			}
119
120
121	greg	1.8	ambnotify(obj) /* record new modifier */
122			OBJECT obj;
123			{
124	greg	1.11	static int hitlimit = 0;
125	greg	1.8	register OBJREC *o = objptr(obj);
126			register char **amblp;
127
128	greg	1.11	if (hitlimit \|\| !ismodifier(o->otype))
129	greg	1.8	return;
130			for (amblp = amblist; *amblp != NULL; amblp++)
131			if (!strcmp(o->oname, *amblp)) {
132	greg	1.11	if (ambset[0] >= MAXASET) {
133			error(WARNING, "too many modifiers in ambient list");
134			hitlimit++;
135			return; /* should this be fatal? */
136			}
137	greg	1.8	insertelem(ambset, obj);
138			return;
139	greg	1.1	}
140			}
141
142
143			ambient(acol, r) /* compute ambient component for ray */
144			COLOR acol;
145			register RAY *r;
146			{
147			static int rdepth = 0; /* ambient recursion */
148	greg	1.16	double d;
149	greg	1.1
150			if (ambdiv <= 0) /* no ambient calculation */
151			goto dumbamb;
152			/* check number of bounces */
153	greg	1.16	if (rdepth >= ambounce)
154	greg	1.1	goto dumbamb;
155			/* check ambient list */
156			if (ambincl != -1 && r->ro != NULL &&
157			ambincl != inset(ambset, r->ro->omod))
158			goto dumbamb;
159
160			if (ambacc <= FTINY) { /* no ambient storage */
161	greg	1.16	rdepth++;
162			d = doambient(acol, r, r->rweight, NULL, NULL);
163			rdepth--;
164			if (d == 0.0)
165	greg	1.1	goto dumbamb;
166	greg	1.16	return;
167	greg	1.1	}
168			/* get ambient value */
169			setcolor(acol, 0.0, 0.0, 0.0);
170	greg	1.16	d = sumambient(acol, r, rdepth,
171			&atrunk, thescene.cuorg, thescene.cusize);
172			if (d > FTINY)
173			scalecolor(acol, 1.0/d);
174			else {
175			d = makeambient(acol, r, rdepth++);
176			rdepth--;
177			}
178			if (d > FTINY)
179			return;
180	greg	1.1	dumbamb: /* return global value */
181			copycolor(acol, ambval);
182			}
183
184
185			double
186	greg	1.16	sumambient(acol, r, al, at, c0, s) /* get interpolated ambient value */
187	greg	1.1	COLOR acol;
188			register RAY *r;
189	greg	1.16	int al;
190	greg	1.1	AMBTREE *at;
191			FVECT c0;
192			double s;
193			{
194			extern double sqrt();
195			double d, e1, e2, wt, wsum;
196			COLOR ct;
197			FVECT ck0;
198			int i;
199			register int j;
200			register AMBVAL *av;
201	greg	1.7	/* do this node */
202	greg	1.1	wsum = 0.0;
203			for (av = at->alist; av != NULL; av = av->next) {
204			/*
205	greg	1.16	* Ambient level test.
206	greg	1.1	*/
207	greg	1.16	if (av->lvl > al \|\| av->weight < r->rweight-FTINY)
208	greg	1.1	continue;
209			/*
210			* Ambient radius test.
211			*/
212			e1 = 0.0;
213			for (j = 0; j < 3; j++) {
214			d = av->pos[j] - r->rop[j];
215			e1 += d * d;
216			}
217			e1 /= av->rad * av->rad;
218			if (e1 > ambaccambacc1.21)
219			continue;
220			/*
221			* Normal direction test.
222			*/
223			e2 = (1.0 - DOT(av->dir, r->ron)) * r->rweight;
224			if (e2 < 0.0) e2 = 0.0;
225			if (e1 + e2 > ambaccambacc1.21)
226			continue;
227			/*
228			* Ray behind test.
229			*/
230			d = 0.0;
231			for (j = 0; j < 3; j++)
232			d += (r->rop[j] - av->pos[j]) *
233			(av->dir[j] + r->ron[j]);
234	greg	1.18	if (d0.5 < -minaradambacc-.001)
235	greg	1.1	continue;
236			/*
237			* Jittering final test reduces image artifacts.
238			*/
239			wt = sqrt(e1) + sqrt(e2);
240	greg	2.2	wt = .9 + .2urand(9015+samplendx);
241	greg	1.6	if (wt > ambacc)
242	greg	1.1	continue;
243			if (wt <= 1e-3)
244			wt = 1e3;
245			else
246			wt = 1.0 / wt;
247			wsum += wt;
248	greg	1.15	extambient(ct, av, r->rop, r->ron);
249	greg	1.1	scalecolor(ct, wt);
250			addcolor(acol, ct);
251	greg	1.7	}
252			if (at->kid == NULL)
253			return(wsum);
254			/* do children */
255			s *= 0.5;
256			for (i = 0; i < 8; i++) {
257			for (j = 0; j < 3; j++) {
258			ck0[j] = c0[j];
259			if (1<<j & i)
260			ck0[j] += s;
261			if (r->rop[j] < ck0[j] - OCTSCALE*s)
262			break;
263			if (r->rop[j] > ck0[j] + (1.0+OCTSCALE)*s)
264			break;
265			}
266			if (j == 3)
267	greg	1.16	wsum += sumambient(acol, r, al, at->kid+i, ck0, s);
268	greg	1.1	}
269			return(wsum);
270			}
271
272
273			double
274	greg	1.16	makeambient(acol, r, al) /* make a new ambient value */
275	greg	1.1	COLOR acol;
276			register RAY *r;
277	greg	1.16	int al;
278	greg	1.1	{
279			AMBVAL amb;
280	greg	1.14	FVECT gp, gd;
281	greg	1.16	/* compute weight */
282			amb.weight = pow(AVGREFL, (double)al);
283	greg	1.17	if (r->rweight < 0.2amb.weight) / heuristic */
284	greg	1.16	amb.weight = r->rweight;
285			/* compute ambient */
286			amb.rad = doambient(acol, r, amb.weight, gp, gd);
287	greg	1.1	if (amb.rad == 0.0)
288			return(0.0);
289			/* store it */
290			VCOPY(amb.pos, r->rop);
291			VCOPY(amb.dir, r->ron);
292	greg	1.16	amb.lvl = al;
293	greg	1.1	copycolor(amb.val, acol);
294	greg	1.14	VCOPY(amb.gpos, gp);
295			VCOPY(amb.gdir, gd);
296	greg	1.1	/* insert into tree */
297			avinsert(&amb, &atrunk, thescene.cuorg, thescene.cusize);
298			avsave(&amb); /* write to file */
299			return(amb.rad);
300	greg	1.15	}
301
302
303			extambient(cr, ap, pv, nv) /* extrapolate value at pv, nv */
304			COLOR cr;
305			register AMBVAL *ap;
306			FVECT pv, nv;
307			{
308			FVECT v1, v2;
309			register int i;
310			double d;
311
312			d = 1.0; /* zeroeth order */
313			/* gradient due to translation */
314			for (i = 0; i < 3; i++)
315			d += ap->gpos[i]*(pv[i]-ap->pos[i]);
316			/* gradient due to rotation */
317			VCOPY(v1, ap->dir);
318			fcross(v2, v1, nv);
319			d += DOT(ap->gdir, v2);
320			if (d <= 0.0) {
321			setcolor(cr, 0.0, 0.0, 0.0);
322			return;
323			}
324			copycolor(cr, ap->val);
325			scalecolor(cr, d);
326	greg	1.1	}
327
328
329			static
330			avsave(av) /* save an ambient value */
331			AMBVAL *av;
332			{
333			static int nunflshed = 0;
334	greg	2.6
335	greg	1.1	if (ambfp == NULL)
336			return;
337	greg	2.5	if (writambval(av, ambfp) < 0)
338	greg	1.1	goto writerr;
339			if (++nunflshed >= AMBFLUSH) {
340			if (fflush(ambfp) == EOF)
341			goto writerr;
342			nunflshed = 0;
343			}
344			return;
345			writerr:
346			error(SYSTEM, "error writing ambient file");
347			}
348
349
350			static
351			avinsert(aval, at, c0, s) /* insert ambient value in a tree */
352			AMBVAL *aval;
353			register AMBTREE *at;
354			FVECT c0;
355			double s;
356			{
357			FVECT ck0;
358			int branch;
359			register AMBVAL *av;
360			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			}