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/* Copyright (c) 1992 Regents of the University of California */ |
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/* Copyright (c) 1993 Regents of the University of California */ |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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/* |
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* ambient.c - routines dealing with ambient (inter-reflected) component. |
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* |
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* 5/9/86 |
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*/ |
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#include "ray.h" |
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static AMBTREE atrunk; /* our ambient trunk node */ |
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static char *ambfname = NULL; /* ambient file name */ |
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static FILE *ambfp = NULL; /* ambient file pointer */ |
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#define AMBFLUSH (BUFSIZ/AMBVALSIZ) |
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/* init ambient limits */ |
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setambres(ambres); |
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/* open ambient file */ |
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if (afile != NULL) |
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if ((ambfname = afile) != NULL) |
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if ((ambfp = fopen(afile, "r+")) != NULL) { |
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initambfile(0); |
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headlen = ftell(ambfp); |
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fputformat(AMBFMT, ambfp); |
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putc('\n', ambfp); |
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putambmagic(ambfp); |
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fflush(ambfp); |
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#ifndef NIX |
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sync(); /* protect against NFS buffering */ |
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#endif |
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} else if (checkheader(ambfp, AMBFMT, NULL) < 0 || !hasambmagic(ambfp)) |
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error(USER, "bad ambient file"); |
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ambsync(); |
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} |
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#else |
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#include <sys/types.h> |
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#include <sys/stat.h> |
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static |
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ambsync() /* synchronize ambient file */ |
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{ |
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static FILE *ambinp = NULL; |
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static long lastpos = -1; |
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struct flock fls; |
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struct stat sts; |
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#define flen sts.st_size |
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long flen; |
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AMBVAL avs; |
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long lastpos; |
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register int n; |
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/* gain exclusive access */ |
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fls.l_type = F_WRLCK; |
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fls.l_len = 0L; |
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if (fcntl(fileno(ambfp), F_SETLKW, &fls) < 0) |
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error(SYSTEM, "cannot lock ambient file"); |
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if (lastpos < 0) /* initializing */ |
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goto syncend; |
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/* see if file has grown */ |
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lastpos = lseek(fileno(ambfp), 0L, 1); /* get previous position */ |
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if (fstat(fileno(ambfp), &sts) < 0) /* get current length */ |
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error(SYSTEM, "cannot stat ambient file"); |
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if (n = (flen - lastpos)/AMBVALSIZ) { /* file has grown */ |
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if (ambinp == NULL) { /* use duplicate file */ |
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ambinp = fdopen(dup(fileno(ambfp)), "r"); |
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if ((flen = lseek(fileno(ambfp), 0L, 2)) < 0) |
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error(SYSTEM, "cannot seek on ambient file"); |
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if (n = flen - lastpos) { /* file has grown */ |
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if (ambinp == NULL) { |
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ambinp = fopen(ambfname, "r"); |
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if (ambinp == NULL) |
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error(SYSTEM, "fdopen failed in ambsync"); |
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error(SYSTEM, "fopen failed in ambsync"); |
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} |
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while (n--) { /* load contributed values */ |
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if (fseek(ambinp, lastpos, 0) < 0) |
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error(SYSTEM, "fseek failed in ambsync"); |
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while (n >= AMBVALSIZ) { /* load contributed values */ |
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readambval(&avs, ambinp); |
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avinsert(&avs,&atrunk,thescene.cuorg,thescene.cusize); |
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} /* moves shared file pointer */ |
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if (n = (flen - lastpos)%AMBVALSIZ) /* alignment */ |
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n -= AMBVALSIZ; |
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} |
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if (n) /* alignment */ |
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lseek(fileno(ambfp), flen-n, 0); |
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} |
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syncend: |
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n = fflush(ambfp); /* calls write() at last */ |
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lastpos = lseek(fileno(ambfp), 0L, 1); |
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fls.l_type = F_UNLCK; /* release file */ |
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fcntl(fileno(ambfp), F_SETLKW, &fls); |
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return(n); |
