ViewVC Help
View File | Revision Log | Show Annotations | Download File | Root Listing
root/radiance/ray/src/rt/rpict.c
Revision: 2.49
Committed: Tue Mar 3 19:14:28 1998 UTC (26 years, 2 months ago) by gwlarson
Content type: text/plain
Branch: MAIN
Changes since 2.48: +30 -6 lines
Log Message:
added -pm option for motion blurring

File Contents

# Content
1 /* Copyright (c) 1996 Regents of the University of California */
2
3 #ifndef lint
4 static char SCCSid[] = "$SunId$ LBL";
5 #endif
6
7 /*
8 * rpict.c - routines and variables for picture generation.
9 */
10
11 #include "ray.h"
12
13 #include <sys/types.h>
14
15 #ifndef NIX
16 #ifdef BSD
17 #include <sys/time.h>
18 #include <sys/resource.h>
19 #else
20 #include <sys/times.h>
21 #include <unistd.h>
22 #endif
23 #endif
24
25 extern time_t time();
26
27 #include <signal.h>
28
29 #include "view.h"
30
31 #include "resolu.h"
32
33 #include "random.h"
34
35 #include "paths.h"
36
37 #define RFTEMPLATE "rfXXXXXX"
38
39 #ifndef SIGCONT
40 #define SIGCONT SIGIO
41 #endif
42
43 int dimlist[MAXDIM]; /* sampling dimensions */
44 int ndims = 0; /* number of sampling dimensions */
45 int samplendx; /* sample index number */
46
47 VIEW ourview = STDVIEW; /* view parameters */
48 int hresolu = 512; /* horizontal resolution */
49 int vresolu = 512; /* vertical resolution */
50 double pixaspect = 1.0; /* pixel aspect ratio */
51
52 int psample = 4; /* pixel sample size */
53 double maxdiff = .05; /* max. difference for interpolation */
54 double dstrpix = 0.67; /* square pixel distribution */
55
56 double mblur = 0.; /* motion blur parameter */
57
58 double dstrsrc = 0.0; /* square source distribution */
59 double shadthresh = .05; /* shadow threshold */
60 double shadcert = .5; /* shadow certainty */
61 int directrelay = 1; /* number of source relays */
62 int vspretest = 512; /* virtual source pretest density */
63 int directvis = 1; /* sources visible? */
64 double srcsizerat = .25; /* maximum ratio source size/dist. */
65
66 COLOR cextinction = BLKCOLOR; /* global extinction coefficient */
67 COLOR salbedo = BLKCOLOR; /* global scattering albedo */
68 double seccg = 0.; /* global scattering eccentricity */
69 double ssampdist = 0.; /* scatter sampling distance */
70
71 double specthresh = .15; /* specular sampling threshold */
72 double specjitter = 1.; /* specular sampling jitter */
73
74 int backvis = 1; /* back face visibility */
75
76 int maxdepth = 6; /* maximum recursion depth */
77 double minweight = 5e-3; /* minimum ray weight */
78
79 COLOR ambval = BLKCOLOR; /* ambient value */
80 int ambvwt = 0; /* initial weight for ambient value */
81 double ambacc = 0.2; /* ambient accuracy */
82 int ambres = 32; /* ambient resolution */
83 int ambdiv = 128; /* ambient divisions */
84 int ambssamp = 0; /* ambient super-samples */
85 int ambounce = 0; /* ambient bounces */
86 char *amblist[128]; /* ambient include/exclude list */
87 int ambincl = -1; /* include == 1, exclude == 0 */
88
89 #ifdef MSDOS
90 int ralrm = 60; /* seconds between reports */
91 #else
92 int ralrm = 0; /* seconds between reports */
93 #endif
94
95 double pctdone = 0.0; /* percentage done */
96
97 time_t tlastrept = 0L; /* time at last report */
98
99 extern time_t tstart; /* starting time */
100
101 extern unsigned long nrays; /* number of rays traced */
102
103 #define MAXDIV 16 /* maximum sample size */
104
105 #define pixjitter() (.5+dstrpix*(.5-frandom()))
106
107 int hres, vres; /* resolution for this frame */
108
109 static VIEW lastview; /* the previous view input */
110
111 extern char *mktemp();
112
113 double pixvalue();
114
115 #ifdef NIX
116 #define file_exists(f) (access(f,F_OK)==0)
117 #else
118 #include <sys/types.h>
119 #include <sys/stat.h>
120 int
121 file_exists(fname) /* ordinary file exists? */
122 char *fname;
123 {
124 struct stat sbuf;
125 if (stat(fname, &sbuf) < 0) return(0);
126 return((sbuf.st_mode & S_IFREG) != 0);
127 }
128 #endif
129
130
131 quit(code) /* quit program */
132 int code;
133 {
134 if (code) /* report status */
135 report();
136 headclean(); /* delete header file */
137 pfclean(); /* clean up persist files */
138 exit(code);
139 }
140
141
142 #ifndef NIX
143 report() /* report progress */
144 {
145 extern char *myhostname();
146 double u, s;
147 #ifdef BSD
148 struct rusage rubuf;
149 #else
150 struct tms tbuf;
151 double period;
152 #endif
153
154 tlastrept = time((time_t *)NULL);
155 #ifdef BSD
156 getrusage(RUSAGE_SELF, &rubuf);
157 u = rubuf.ru_utime.tv_sec + rubuf.ru_utime.tv_usec/1e6;
158 s = rubuf.ru_stime.tv_sec + rubuf.ru_stime.tv_usec/1e6;
159 getrusage(RUSAGE_CHILDREN, &rubuf);
160 u += rubuf.ru_utime.tv_sec + rubuf.ru_utime.tv_usec/1e6;
161 s += rubuf.ru_stime.tv_sec + rubuf.ru_stime.tv_usec/1e6;
162 #else
163 times(&tbuf);
164 #ifdef _SC_CLK_TCK
165 period = 1.0 / sysconf(_SC_CLK_TCK);
166 #else
167 period = 1.0 / 60.0;
168 #endif
169 u = ( tbuf.tms_utime + tbuf.tms_cutime ) * period;
170 s = ( tbuf.tms_stime + tbuf.tms_cstime ) * period;
171 #endif
172
173 sprintf(errmsg,
174 "%lu rays, %4.2f%% after %.3fu %.3fs %.3fr hours on %s\n",
175 nrays, pctdone, u/3600., s/3600.,
176 (tlastrept-tstart)/3600., myhostname());
177 eputs(errmsg);
178 #ifndef BSD
179 signal(SIGCONT, report);
180 #endif
181 }
182 #else
183 report() /* report progress */
184 {
185 tlastrept = time((time_t *)NULL);
186 sprintf(errmsg, "%lu rays, %4.2f%% after %5.4f hours\n",
187 nrays, pctdone, (tlastrept-tstart)/3600.0);
188 eputs(errmsg);
189 }
190 #endif
191
192
193 rpict(seq, pout, zout, prvr) /* generate image(s) */
194 int seq;
195 char *pout, *zout, *prvr;
196 /*
197 * If seq is greater than zero, then we will render a sequence of
198 * images based on view parameter strings read from the standard input.
199 * If pout is NULL, then all images will be sent to the standard ouput.
200 * If seq is greater than zero and prvr is an integer, then it is the
201 * frame number at which rendering should begin. Preceeding view parameter
202 * strings will be skipped in the input.
203 * If pout and prvr are the same, prvr is renamed to avoid overwriting.
204 * Note that pout and zout should contain %d format specifications for
205 * sequenced file naming.
206 */
207 {
208 extern char *rindex(), *strncpy(), *strcat(), *strcpy();
209 char fbuf[128], fbuf2[128];
210 int npicts;
211 register char *cp;
212 RESOLU rs;
213 double pa;
214 /* check sampling */
215 if (psample < 1)
216 psample = 1;
217 else if (psample > MAXDIV) {
218 sprintf(errmsg, "pixel sampling reduced from %d to %d",
219 psample, MAXDIV);
220 error(WARNING, errmsg);
221 psample = MAXDIV;
222 }
223 /* get starting frame */
224 if (seq <= 0)
225 seq = 0;
226 else if (prvr != NULL && isint(prvr)) {
227 register int rn; /* skip to specified view */
228 if ((rn = atoi(prvr)) < seq)
229 error(USER, "recover frame less than start frame");
230 if (pout == NULL)
231 error(USER, "missing output file specification");
232 for ( ; seq < rn; seq++)
233 if (nextview(stdin) == EOF)
234 error(USER, "unexpected EOF on view input");
235 prvr = fbuf; /* mark for renaming */
236 }
237 if (pout != NULL & prvr != NULL) {
238 sprintf(fbuf, pout, seq);
239 if (!strcmp(prvr, fbuf)) { /* rename */
240 strcpy(fbuf2, fbuf);
241 for (cp = fbuf2; *cp; cp++)
242 ;
243 while (cp > fbuf2 && !ISDIRSEP(cp[-1]))
244 cp--;
245 strcpy(cp, RFTEMPLATE);
246 prvr = mktemp(fbuf2);
247 if (rename(fbuf, prvr) < 0)
248 if (errno == ENOENT) { /* ghost file */
249 sprintf(errmsg,
250 "new output file \"%s\"",
251 fbuf);
252 error(WARNING, errmsg);
253 prvr = NULL;
254 } else { /* serious error */
255 sprintf(errmsg,
256 "cannot rename \"%s\" to \"%s\"",
257 fbuf, prvr);
258 error(SYSTEM, errmsg);
259 }
260 }
261 }
262 npicts = 0; /* render sequence */
263 do {
264 if (seq && nextview(stdin) == EOF)
265 break;
266 pctdone = 0.0;
267 if (pout != NULL) {
268 sprintf(fbuf, pout, seq);
269 if (file_exists(fbuf)) {
270 if (prvr != NULL || !strcmp(fbuf, pout)) {
271 sprintf(errmsg,
272 "output file \"%s\" exists",
273 fbuf);
274 error(USER, errmsg);
275 }
276 continue; /* don't clobber */
277 }
278 if (freopen(fbuf, "w", stdout) == NULL) {
279 sprintf(errmsg,
280 "cannot open output file \"%s\"", fbuf);
281 error(SYSTEM, errmsg);
282 }
283 #ifdef MSDOS
284 setmode(fileno(stdout), O_BINARY);
285 #endif
286 dupheader();
287 }
288 hres = hresolu; vres = vresolu; pa = pixaspect;
289 if (prvr != NULL)
290 if (viewfile(prvr, &ourview, &rs) <= 0
291 || rs.or != PIXSTANDARD) {
292 sprintf(errmsg,
293 "cannot recover view parameters from \"%s\"", prvr);
294 error(WARNING, errmsg);
295 } else {
296 pa = 0.0;
297 hres = scanlen(&rs);
298 vres = numscans(&rs);
299 }
300 if ((cp = setview(&ourview)) != NULL)
301 error(USER, cp);
302 normaspect(viewaspect(&ourview), &pa, &hres, &vres);
303 if (seq) {
304 if (ralrm > 0) {
305 fprintf(stderr, "FRAME %d:", seq);
306 fprintview(&ourview, stderr);
307 putc('\n', stderr);
308 fflush(stderr);
309 }
310 printf("FRAME=%d\n", seq);
311 }
312 fputs(VIEWSTR, stdout);
313 fprintview(&ourview, stdout);
314 putchar('\n');
315 if (pa < .99 || pa > 1.01)
316 fputaspect(pa, stdout);
317 fputformat(COLRFMT, stdout);
318 putchar('\n');
319 if (zout != NULL)
320 sprintf(cp=fbuf, zout, seq);
321 else
322 cp = NULL;
323 render(cp, prvr);
324 prvr = NULL;
325 npicts++;
326 } while (seq++);
327 /* check that we did something */
328 if (npicts == 0)
329 error(WARNING, "no output produced");
330 }
331
332
333 nextview(fp) /* get next view from fp */
334 FILE *fp;
335 {
336 char linebuf[256];
337
338 copystruct(&lastview, &ourview);
339 while (fgets(linebuf, sizeof(linebuf), fp) != NULL)
340 if (isview(linebuf) && sscanview(&ourview, linebuf) > 0)
341 return(0);
342 return(EOF);
343 }
344
345
346 render(zfile, oldfile) /* render the scene */
347 char *zfile, *oldfile;
348 {
349 extern long lseek();
350 COLOR *scanbar[MAXDIV+1]; /* scanline arrays of pixel values */
351 float *zbar[MAXDIV+1]; /* z values */
352 char *sampdens; /* previous sample density */
353 int ypos; /* current scanline */
354 int ystep; /* current y step size */
355 int hstep; /* h step size */
356 int zfd;
357 COLOR *colptr;
358 float *zptr;
359 register int i;
360 /* allocate scanlines */
361 for (i = 0; i <= psample; i++) {
362 scanbar[i] = (COLOR *)malloc(hres*sizeof(COLOR));
363 if (scanbar[i] == NULL)
364 goto memerr;
365 }
366 hstep = (psample*140+49)/99; /* quincunx sampling */
367 ystep = (psample*99+70)/140;
368 if (hstep > 2) {
369 i = hres/hstep + 2;
370 if ((sampdens = malloc(i)) == NULL)
371 goto memerr;
372 while (i--)
373 sampdens[i] = hstep;
374 } else
375 sampdens = NULL;
376 /* open z-file */
377 if (zfile != NULL) {
378 if ((zfd = open(zfile, O_WRONLY|O_CREAT, 0666)) == -1) {
379 sprintf(errmsg, "cannot open z-file \"%s\"", zfile);
380 error(SYSTEM, errmsg);
381 }
382 #ifdef MSDOS
383 setmode(zfd, O_BINARY);
384 #endif
385 for (i = 0; i <= psample; i++) {
386 zbar[i] = (float *)malloc(hres*sizeof(float));
387 if (zbar[i] == NULL)
388 goto memerr;
389 }
390 } else {
391 zfd = -1;
392 for (i = 0; i <= psample; i++)
393 zbar[i] = NULL;
394 }
395 /* write out boundaries */
396 fprtresolu(hres, vres, stdout);
397 /* recover file and compute first */
398 i = salvage(oldfile);
399 if (i >= vres)
400 goto alldone;
401 if (zfd != -1 && i > 0 &&
402 lseek(zfd, (long)i*hres*sizeof(float), 0) == -1)
403 error(SYSTEM, "z-file seek error in render");
404 pctdone = 100.0*i/vres;
405 if (ralrm > 0) /* report init stats */
406 report();
407 #ifndef BSD
408 else
409 #endif
410 signal(SIGCONT, report);
411 ypos = vres-1 - i; /* initialize sampling */
412 if (directvis)
413 init_drawsources(psample);
414 fillscanline(scanbar[0], zbar[0], sampdens, hres, ypos, hstep);
415 /* compute scanlines */
416 for (ypos -= ystep; ypos > -ystep; ypos -= ystep) {
417 /* bottom adjust? */
418 if (ypos < 0) {
419 ystep += ypos;
420 ypos = 0;
421 }
422 colptr = scanbar[ystep]; /* move base to top */
423 scanbar[ystep] = scanbar[0];
424 scanbar[0] = colptr;
425 zptr = zbar[ystep];
426 zbar[ystep] = zbar[0];
427 zbar[0] = zptr;
428 /* fill base line */
429 fillscanline(scanbar[0], zbar[0], sampdens,
430 hres, ypos, hstep);
431 /* fill bar */
432 fillscanbar(scanbar, zbar, hres, ypos, ystep);
433 if (directvis) /* add bitty sources */
434 drawsources(scanbar, zbar, 0, hres, ypos, ystep);
435 /* write it out */
436 #ifndef BSD
437 signal(SIGCONT, SIG_IGN); /* don't interrupt writes */
438 #endif
439 for (i = ystep; i > 0; i--) {
440 if (zfd != -1 && write(zfd, (char *)zbar[i],
441 hres*sizeof(float))
442 < hres*sizeof(float))
443 goto writerr;
444 if (fwritescan(scanbar[i], hres, stdout) < 0)
445 goto writerr;
446 }
447 if (fflush(stdout) == EOF)
448 goto writerr;
449 /* record progress */
450 pctdone = 100.0*(vres-1-ypos)/vres;
451 if (ralrm > 0 && time((time_t *)NULL) >= tlastrept+ralrm)
452 report();
453 #ifndef BSD
454 else
455 signal(SIGCONT, report);
456 #endif
457 }
458 /* clean up */
459 signal(SIGCONT, SIG_IGN);
460 if (zfd != -1 && write(zfd, (char *)zbar[0], hres*sizeof(float))
461 < hres*sizeof(float))
462 goto writerr;
463 fwritescan(scanbar[0], hres, stdout);
464 if (fflush(stdout) == EOF)
465 goto writerr;
466 alldone:
467 if (zfd != -1) {
468 if (close(zfd) == -1)
469 goto writerr;
470 for (i = 0; i <= psample; i++)
471 free((char *)zbar[i]);
472 }
473 for (i = 0; i <= psample; i++)
474 free((char *)scanbar[i]);
475 if (sampdens != NULL)
476 free(sampdens);
477 pctdone = 100.0;
478 if (ralrm > 0)
479 report();
480 signal(SIGCONT, SIG_DFL);
481 return;
482 writerr:
483 error(SYSTEM, "write error in render");
484 memerr:
485 error(SYSTEM, "out of memory in render");
486 }
487
488
489 fillscanline(scanline, zline, sd, xres, y, xstep) /* fill scan at y */
490 register COLOR *scanline;
491 register float *zline;
492 register char *sd;
493 int xres, y, xstep;
494 {
495 static int nc = 0; /* number of calls */
496 int bl = xstep, b = xstep;
497 double z;
498 register int i;
499
500 z = pixvalue(scanline[0], 0, y);
501 if (zline) zline[0] = z;
502 /* zig-zag start for quincunx pattern */
503 for (i = ++nc & 1 ? xstep : xstep/2; i < xres-1+xstep; i += xstep) {
504 if (i >= xres) {
505 xstep += xres-1-i;
506 i = xres-1;
507 }
508 z = pixvalue(scanline[i], i, y);
509 if (zline) zline[i] = z;
510 if (sd) b = sd[0] > sd[1] ? sd[0] : sd[1];
511 if (i <= xstep)
512 b = fillsample(scanline, zline, 0, y, i, 0, b/2);
513 else
514 b = fillsample(scanline+i-xstep,
515 zline ? zline+i-xstep : (float *)NULL,
516 i-xstep, y, xstep, 0, b/2);
517 if (sd) *sd++ = nc & 1 ? bl : b;
518 bl = b;
519 }
520 if (sd && nc & 1) *sd = bl;
521 }
522
523
524 fillscanbar(scanbar, zbar, xres, y, ysize) /* fill interior */
525 register COLOR *scanbar[];
526 register float *zbar[];
527 int xres, y, ysize;
528 {
529 COLOR vline[MAXDIV+1];
530 float zline[MAXDIV+1];
531 int b = ysize;
532 register int i, j;
533
534 for (i = 0; i < xres; i++) {
535 copycolor(vline[0], scanbar[0][i]);
536 copycolor(vline[ysize], scanbar[ysize][i]);
537 if (zbar[0]) {
538 zline[0] = zbar[0][i];
539 zline[ysize] = zbar[ysize][i];
540 }
541 b = fillsample(vline, zbar[0] ? zline : (float *)NULL,
542 i, y, 0, ysize, b/2);
543
544 for (j = 1; j < ysize; j++)
545 copycolor(scanbar[j][i], vline[j]);
546 if (zbar[0])
547 for (j = 1; j < ysize; j++)
548 zbar[j][i] = zline[j];
549 }
550 }
551
552
553 int
554 fillsample(colline, zline, x, y, xlen, ylen, b) /* fill interior points */
555 register COLOR *colline;
556 register float *zline;
557 int x, y;
558 int xlen, ylen;
559 int b;
560 {
561 double ratio;
562 double z;
563 COLOR ctmp;
564 int ncut;
565 register int len;
566
567 if (xlen > 0) /* x or y length is zero */
568 len = xlen;
569 else
570 len = ylen;
571
572 if (len <= 1) /* limit recursion */
573 return(0);
574
575 if (b > 0 ||
576 (zline && 2.*fabs(zline[0]-zline[len]) > maxdiff*(zline[0]+zline[len]))
577 || bigdiff(colline[0], colline[len], maxdiff)) {
578
579 z = pixvalue(colline[len>>1], x + (xlen>>1), y + (ylen>>1));
580 if (zline) zline[len>>1] = z;
581 ncut = 1;
582 } else { /* interpolate */
583 copycolor(colline[len>>1], colline[len]);
584 ratio = (double)(len>>1) / len;
585 scalecolor(colline[len>>1], ratio);
586 if (zline) zline[len>>1] = zline[len] * ratio;
587 ratio = 1.0 - ratio;
588 copycolor(ctmp, colline[0]);
589 scalecolor(ctmp, ratio);
590 addcolor(colline[len>>1], ctmp);
591 if (zline) zline[len>>1] += zline[0] * ratio;
592 ncut = 0;
593 }
594 /* recurse */
595 ncut += fillsample(colline, zline, x, y, xlen>>1, ylen>>1, (b-1)/2);
596
597 ncut += fillsample(colline+(len>>1),
598 zline ? zline+(len>>1) : (float *)NULL,
599 x+(xlen>>1), y+(ylen>>1),
600 xlen-(xlen>>1), ylen-(ylen>>1), b/2);
601
602 return(ncut);
603 }
604
605
606 double
607 pixvalue(col, x, y) /* compute pixel value */
608 COLOR col; /* returned color */
609 int x, y; /* pixel position */
610 {
611 RAY thisray;
612 FVECT lorg, ldir;
613 double hpos, vpos, lmax, d;
614 /* compute view ray */
615 hpos = (x+pixjitter())/hres;
616 vpos = (y+pixjitter())/vres;
617 if ((thisray.rmax = viewray(thisray.rorg, thisray.rdir,
618 &ourview, hpos, vpos)) < -FTINY) {
619 setcolor(col, 0.0, 0.0, 0.0);
620 return(0.0);
621 }
622
623 samplendx = pixnumber(x,y,hres,vres); /* set pixel index */
624
625 /* optional motion blur */
626 if (lastview.type && mblur > FTINY && (lmax = viewray(lorg, ldir,
627 &lastview, hpos, vpos)) >= -FTINY) {
628 register int i;
629 register double d = mblur*(.5-urand(281+samplendx));
630
631 thisray.rmax = (1.-d)*thisray.rmax + d*lmax;
632 for (i = 3; i--; ) {
633 thisray.rorg[i] = (1.-d)*thisray.rorg[i] + d*lorg[i];
634 thisray.rdir[i] = (1.-d)*thisray.rdir[i] + d*ldir[i];
635 }
636 if (normalize(thisray.rdir) == 0.0)
637 return(0.0);
638 }
639
640 rayorigin(&thisray, NULL, PRIMARY, 1.0);
641
642 rayvalue(&thisray); /* trace ray */
643
644 copycolor(col, thisray.rcol); /* return color */
645
646 return(thisray.rt); /* return distance */
647 }
648
649
650 int
651 salvage(oldfile) /* salvage scanlines from killed program */
652 char *oldfile;
653 {
654 COLR *scanline;
655 FILE *fp;
656 int x, y;
657
658 if (oldfile == NULL)
659 goto gotzip;
660
661 if ((fp = fopen(oldfile, "r")) == NULL) {
662 sprintf(errmsg, "cannot open recover file \"%s\"", oldfile);
663 error(WARNING, errmsg);
664 goto gotzip;
665 }
666 #ifdef MSDOS
667 setmode(fileno(fp), O_BINARY);
668 #endif
669 /* discard header */
670 getheader(fp, NULL, NULL);
671 /* get picture size */
672 if (!fscnresolu(&x, &y, fp)) {
673 sprintf(errmsg, "bad recover file \"%s\" - not removed",
674 oldfile);
675 error(WARNING, errmsg);
676 fclose(fp);
677 goto gotzip;
678 }
679
680 if (x != hres || y != vres) {
681 sprintf(errmsg, "resolution mismatch in recover file \"%s\"",
682 oldfile);
683 error(USER, errmsg);
684 }
685
686 scanline = (COLR *)malloc(hres*sizeof(COLR));
687 if (scanline == NULL)
688 error(SYSTEM, "out of memory in salvage");
689 for (y = 0; y < vres; y++) {
690 if (freadcolrs(scanline, hres, fp) < 0)
691 break;
692 if (fwritecolrs(scanline, hres, stdout) < 0)
693 goto writerr;
694 }
695 if (fflush(stdout) == EOF)
696 goto writerr;
697 free((char *)scanline);
698 fclose(fp);
699 unlink(oldfile);
700 return(y);
701 gotzip:
702 if (fflush(stdout) == EOF)
703 error(SYSTEM, "error writing picture header");
704 return(0);
705 writerr:
706 sprintf(errmsg, "write error during recovery of \"%s\"", oldfile);
707 error(SYSTEM, errmsg);
708 }
709
710
711 int
712 pixnumber(x, y, xres, yres) /* compute pixel index (brushed) */
713 register int x, y;
714 int xres, yres;
715 {
716 x -= y;
717 while (x < 0)
718 x += xres;
719 return((((x>>2)*yres + y) << 2) + (x & 3));
720 }