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/* Copyright (c) 1991 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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#endif
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/*
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* Compute Glare Index given by program name:
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*
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* guth_dgr - Guth discomfort glare rating
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* guth_vcp - Guth visual comfort probability
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*
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* 12 April 1991 Greg Ward EPFL
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*/
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#include "standard.h"
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#include "view.h"
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extern double erfc();
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double posindex();
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int headline();
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double direct(), guth_dgr(), guth_vcp();
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struct named_func {
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char *name;
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double (*func)();
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} all_funcs[] = {
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{"direct", direct},
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{"guth_dgr", guth_dgr},
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{"guth_vcp", guth_vcp},
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{NULL}
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};
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struct glare_src {
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FVECT dir; /* source direction */
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double dom; /* solid angle */
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double lum; /* average luminance */
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struct glare_src *next;
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} *all_srcs = NULL;
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struct glare_dir {
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double ang; /* angle (in radians) */
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double indirect; /* indirect illuminance */
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struct glare_dir *next;
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} *all_dirs = NULL;
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#define newp(type) (type *)malloc(sizeof(type))
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char *progname;
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int print_header = 1;
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VIEW midview = STDVIEW;
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main(argc, argv)
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int argc;
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char *argv[];
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{
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extern char *rindex();
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struct named_func *funp;
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char *progtail;
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int i;
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/* get program name */
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progname = argv[0];
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progtail = rindex(progname, '/'); /* final component */
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if (progtail == NULL)
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progtail = progname;
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else
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progtail++;
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/* get options */
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for (i = 1; i < argc && argv[i][0] == '-'; i++)
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switch (argv[i][1]) {
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case 't':
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progtail = argv[++i];
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break;
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case 'h':
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print_header = 0;
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break;
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default:
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goto userr;
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}
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if (i < argc-1)
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goto userr;
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if (i == argc-1) /* open file */
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if (freopen(argv[i], "r", stdin) == NULL) {
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perror(argv[i]);
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exit(1);
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}
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/* read header */
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getheader(stdin, headline);
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if (print_header) { /* add to header */
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printargs(i, argv, stdout);
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putchar('\n');
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}
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/* set view */
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if (setview(&midview) != NULL) {
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fprintf(stderr, "%s: bad view information in input\n");
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exit(1);
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}
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/* get findglare data */
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read_input();
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/* find calculation */
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for (funp = all_funcs; funp->name != NULL; funp++)
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if (!strcmp(funp->name, progtail)) {
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print_values(funp->func);
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exit(0); /* we're done */
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}
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/* invalid function */
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fprintf(stderr, "%s: unknown function!\n", progtail);
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exit(1);
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userr:
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fprintf(stderr, "Usage: %s [-t type][-h] [input]\n", progname);
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exit(1);
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}
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headline(s) /* get line from header */
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char *s;
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{
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if (print_header) /* copy to output */
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fputs(s, stdout);
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if (!strncmp(s, VIEWSTR, VIEWSTRL))
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sscanview(&midview, s+VIEWSTRL);
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}
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read_input() /* read glare sources from stdin */
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{
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#define S_SEARCH 0
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#define S_SOURCE 1
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#define S_DIREC 2
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int state = S_SEARCH;
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char buf[128];
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register struct glare_src *gs;
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register struct glare_dir *gd;
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while (fgets(buf, sizeof(buf), stdin) != NULL)
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switch (state) {
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case S_SEARCH:
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if (!strcmp(buf, "BEGIN glare source\n"))
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state = S_SOURCE;
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else if (!strcmp(buf, "BEGIN indirect illuminance\n"))
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state = S_DIREC;
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break;
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case S_SOURCE:
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if (!strncmp(buf, "END", 3)) {
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state = S_SEARCH;
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break;
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}
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if ((gs = newp(struct glare_src)) == NULL)
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goto memerr;
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if (sscanf(buf, "%lf %lf %lf %lf %lf",
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&gs->dir[0], &gs->dir[1], &gs->dir[2],
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&gs->dom, &gs->lum) != 5)
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goto readerr;
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normalize(gs->dir);
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gs->next = all_srcs;
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all_srcs = gs;
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break;
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case S_DIREC:
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if (!strncmp(buf, "END", 3)) {
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state = S_SEARCH;
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break;
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}
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if ((gd = newp(struct glare_dir)) == NULL)
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goto memerr;
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if (sscanf(buf, "%lf %lf",
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&gd->ang, &gd->indirect) != 2)
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goto readerr;
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gd->ang *= PI/180.0; /* convert to radians */
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gd->next = all_dirs;
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all_dirs = gd;
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break;
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}
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return;
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memerr:
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perror(progname);
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exit(1);
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readerr:
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fprintf(stderr, "%s: read error on input\n", progname);
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exit(1);
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#undef S_SEARCH
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#undef S_SOURCE
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#undef S_DIREC
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}
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print_values(funp) /* print out calculations */
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double (*funp)();
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{
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register struct glare_dir *gd;
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for (gd = all_dirs; gd != NULL; gd = gd->next)
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printf("%f\t%f\n", gd->ang*(180.0/PI), (*funp)(gd));
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}
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double
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direct(gd) /* compute direct illuminance */
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struct glare_dir *gd;
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{
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FVECT mydir;
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double d, dval;
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register struct glare_src *gs;
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spinvector(mydir, midview.vdir, midview.vup, gd->ang);
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dval = 0.0;
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for (gs = all_srcs; gs != NULL; gs = gs->next) {
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d = DOT(mydir,gs->dir);
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if (d > FTINY)
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dval += d * gs->dom * gs->lum;
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}
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return(dval);
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}
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/*
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* posindex - compute glare position index from:
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*
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* Source Direction
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* View Direction
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* View Up Direction
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*
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* All vectors are assumed to be normalized.
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* This function is an implementation of the method proposed by
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* Robert Levin in his 1975 JIES article.
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* We return a value less than zero for improper positions.
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*/
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double
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posindex(sd, vd, vu) /* compute position index */
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FVECT sd, vd, vu;
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{
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double sigma, tau;
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double d;
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d = DOT(sd,vd);
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if (d <= 0.0)
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return(-1.0);
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sigma = acos(d) * (180./PI);
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tau = acos(DOT(sd,vu)/sqrt(1.0-d*d)) * (180./PI);
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return( exp( sigma*( (35.2 - tau*.31889 - 1.22*exp(-.22222*tau))*1e-3
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+ sigma*(21. + tau*(.26667 + tau*-.002963))*1e-5 )
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) );
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}
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double
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guth_dgr(gd) /* compute Guth discomfort glare rating */
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struct glare_dir *gd;
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{
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#define q(w) (20.4*w+1.52*pow(w,.2)-.075)
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register struct glare_src *gs;
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double p;
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double sum;
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int n;
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sum = 0.0; n = 0;
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for (gs = all_srcs; gs != NULL; gs = gs->next) {
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p = posindex(gs->dir, midview.vdir, midview.vup);
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if (p <= FTINY)
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continue;
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sum += gs->lum * q(gs->dom) / p;
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n++;
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}
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if (n == 0)
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return(0.0);
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else
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return( pow(
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.5*sum/pow(direct(gd)+gd->indirect,.44),
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pow((double)n, -.0914) ) );
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#undef q
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}
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extern double erf(), erfc();
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#ifndef M_SQRT2
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#define M_SQRT2 1.41421356237309504880
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#endif
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#define norm_integral(z) (1.-.5*erfc((z)/M_SQRT2))
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double
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guth_vcp(gd) /* compute Guth visual comfort probability */
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struct glare_dir *gd;
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{
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return(100.*norm_integral(-6.374+1.3227*log(guth_dgr(gd))));
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}
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