src/util/glarendx.c

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

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

/*
 * Compute Glare Index given by program name or -t option:
 *
 *      dgi -           Daylight Glare Index
 *      brs_gi -        Building Research Station Glare Index (Petherbridge
 *                                                             & Hopkinson)
 *      ugr -           Unified Glare Rating System (Fischer)
 *      guth_dgr -      Guth discomfort glare rating
 *      guth_vcp -      Guth visual comfort probability
 *      cie_cgi -       CIE Glare Index (1983, due to Einhorn)
 *      vert_dir -      Direct vertical illuminance
 *      vert_ind -      Indirect vertical illuminance (from input)
 *      vert_ill -      Total vertical illuminance
 *
 *              12 April 1991   Greg Ward       EPFL
 *              19 April 1993   R. Compagnon    EPFL (added dgi, brs_gi, ugr)
 */
 
#include "standard.h"
#include "view.h"
 
extern double   erfc();
 
double  posindex();
 
double  direct(), guth_dgr(), guth_vcp(), cie_cgi(),
        indirect(), total(), dgi(), brs_gi(), ugr();
 
struct named_func {
        char    *name;
        double  (*func)();
        char    *descrip;
} all_funcs[] = {
        {"dgi", dgi, "Daylight Glare Index"},
        {"brs_gi", brs_gi, "BRS Glare Index"},
        {"ugr", ugr, "Unified Glare Rating"},
        {"guth_vcp", guth_vcp, "Guth Visual Comfort Probability"},
        {"cie_cgi", cie_cgi, "CIE Glare Index (Einhorn)"},
        {"guth_dgr", guth_dgr, "Guth Disability Glare Rating"},
        {"vert_dir", direct, "Direct Vertical Illuminance"},
        {"vert_ill", total, "Total Vertical Illuminance"},
        {"vert_ind", indirect, "Indirect Vertical Illuminance"},
        {NULL}
};
 
struct glare_src {
        FVECT   dir;            /* source direction */
        double  dom;            /* solid angle */
        double  lum;            /* average luminance */
        struct glare_src        *next;
} *all_srcs = NULL;
 
struct glare_dir {
        double  ang;            /* angle (in radians) */
        double  indirect;       /* indirect illuminance */
        struct glare_dir        *next;
} *all_dirs = NULL;
 
#define newp(type)      (type *)malloc(sizeof(type))
 
char    *progname;
int     print_header = 1;
 
VIEW    midview = STDVIEW;
 
int     wrongformat = 0;
 
 
main(argc, argv)
int     argc;
char    *argv[];
{
        extern char     *rindex();
        struct named_func       *funp;
        char    *progtail;
        int     i;
                                        /* get program name */
        progname = argv[0];
        progtail = rindex(progname, '/');       /* final component */
        if (progtail == NULL)
                progtail = progname;
        else
                progtail++;
                                        /* get options */
        for (i = 1; i < argc && argv[i][0] == '-'; i++)
                switch (argv[i][1]) {
                case 't':
                        progtail = argv[++i];
                        break;
                case 'h':
                        print_header = 0;
                        break;
                default:
                        goto userr;
                }
        if (i < argc-1)
                goto userr;
        if (i == argc-1)                /* open file */
                if (freopen(argv[i], "r", stdin) == NULL) {
                        perror(argv[i]);
                        exit(1);
                }
                                        /* find and run calculation */
        for (funp = all_funcs; funp->name != NULL; funp++)
                if (!strcmp(funp->name, progtail)) {
                        init();
                        read_input();
                        if (print_header) {
                                printargs(i, argv, stdout);
                                putchar('\n');
                        }
                        print_values(funp->func);
                        exit(0);                /* we're done */
                }
                                        /* invalid function */
userr:
        fprintf(stderr, "Usage: %s -t type [-h] [input]\n", progname);
        fprintf(stderr, "\twhere 'type' is one of the following:\n");
        for (funp = all_funcs; funp->name != NULL; funp++)
                fprintf(stderr, "\t%12s\t%s\n", funp->name, funp->descrip);
        exit(1);
}
 
 
headline(s)                     /* get line from header */
char    *s;
{
        char    fmt[32];
 
        if (print_header)               /* copy to output */
                fputs(s, stdout);
        if (isview(s))
                sscanview(&midview, s);
        else if (isformat(s)) {
                formatval(fmt, s);
                wrongformat = strcmp(fmt, "ascii");
        }
}
 
 
init()                          /* initialize calculation */
{
                                        /* read header */
        getheader(stdin, headline, NULL);
        if (wrongformat) {
                fprintf(stderr, "%s: bad input format\n", progname);
                exit(1);
        }
                                        /* set view */
        if (setview(&midview) != NULL) {
                fprintf(stderr, "%s: bad view information in input\n",
                                progname);
                exit(1);
        }
}
 
 
read_input()                    /* read glare sources from stdin */
{
#define S_SEARCH        0
#define S_SOURCE        1
#define S_DIREC         2
        int     state = S_SEARCH;
        char    buf[128];
        register struct glare_src       *gs;
        register struct glare_dir       *gd;
 
        while (fgets(buf, sizeof(buf), stdin) != NULL)
                switch (state) {
                case S_SEARCH:
                        if (!strcmp(buf, "BEGIN glare source\n"))
                                state = S_SOURCE;
                        else if (!strcmp(buf, "BEGIN indirect illuminance\n"))
                                state = S_DIREC;
                        break;
                case S_SOURCE:
                        if (!strncmp(buf, "END", 3)) {
                                state = S_SEARCH;
                                break;
                        }
                        if ((gs = newp(struct glare_src)) == NULL)
                                goto memerr;
                        if (sscanf(buf, "%lf %lf %lf %lf %lf",
                                        &gs->dir[0], &gs->dir[1], &gs->dir[2],
                                        &gs->dom, &gs->lum) != 5)
                                goto readerr;
                        normalize(gs->dir);
                        gs->next = all_srcs;
                        all_srcs = gs;
                        break;
                case S_DIREC:
                        if (!strncmp(buf, "END", 3)) {
                                state = S_SEARCH;
                                break;
                        }
                        if ((gd = newp(struct glare_dir)) == NULL)
                                goto memerr;
                        if (sscanf(buf, "%lf %lf",
                                        &gd->ang, &gd->indirect) != 2)
                                goto readerr;
                        gd->ang *= PI/180.0;    /* convert to radians */
                        gd->next = all_dirs;
                        all_dirs = gd;
                        break;
                }
        return;
memerr:
        perror(progname);
        exit(1);
readerr:
        fprintf(stderr, "%s: read error on input\n", progname);
        exit(1);
#undef S_SEARCH
#undef S_SOURCE
#undef S_DIREC
}
 
 
print_values(funp)              /* print out calculations */
double  (*funp)();
{
        register struct glare_dir       *gd;
 
        for (gd = all_dirs; gd != NULL; gd = gd->next)
                printf("%f\t%f\n", gd->ang*(180.0/PI), (*funp)(gd));
}
 
 
double
direct(gd)                      /* compute direct vertical illuminance */
struct glare_dir        *gd;
{
        FVECT   mydir;
        double  d, dval;
        register struct glare_src       *gs;
 
        spinvector(mydir, midview.vdir, midview.vup, gd->ang);
        dval = 0.0;
        for (gs = all_srcs; gs != NULL; gs = gs->next) {
                d = DOT(mydir,gs->dir);
                if (d > FTINY)
                        dval += d * gs->dom * gs->lum;
        }
        return(dval);
}
 
 
double
indirect(gd)                    /* return indirect vertical illuminance */
struct glare_dir        *gd;
{
        return(gd->indirect);
}
 
 
double
total(gd)                       /* return total vertical illuminance */
struct glare_dir        *gd;
{
        return(direct(gd)+gd->indirect);
}
 
 
/*
 * posindex -   compute glare position index from:
 *
 *      Source Direction
 *      View Direction
 *      View Up Direction
 *
 * All vectors are assumed to be normalized.
 * This function is an implementation of the method proposed by
 * Robert Levin in his 1975 JIES article.
 * This calculation presumes the view direction and up vectors perpendicular.
 * We return a value less than zero for improper positions.
 */
 
double
posindex(sd, vd, vu)                    /* compute position index */
FVECT   sd, vd, vu;
{
        double  sigma, tau;
        double  d;
 
        d = DOT(sd,vd);
        if (d <= 0.0)
                return(-1.0);
        if (d >= 1.0)
                return(1.0);
        sigma = acos(d) * (180./PI);
        d = fabs(DOT(sd,vu)/sqrt(1.0-d*d));
        if (d >= 1.0)
                tau = 0.0;
        else
                tau = acos(d) * (180./PI);
        return( exp( sigma*( (35.2 - tau*.31889 - 1.22*exp(-.22222*tau))*1e-3
                        + sigma*(21. + tau*(.26667 + tau*-.002963))*1e-5 )
                ) );
}
 
 
double
dgi(gd)         /* compute Daylight Glare Index */
struct glare_dir        *gd;
{
        register struct glare_src       *gs;
        FVECT   mydir,testdir[7],vhor;
        double  r,omega,p[7],sum;
        int     i,n;
 
        spinvector(mydir, midview.vdir, midview.vup, gd->ang);
        sum = 0.0; n = 0;
        for (gs = all_srcs; gs != NULL; gs = gs->next) {

                /* compute 1/p^2 weighted solid angle of the source */
                r = sqrt(1 - pow(1.-gs->dom/2./PI,2.));
                fcross(vhor,gs->dir,midview.vup);
                normalize(vhor);
                VCOPY(testdir[0],gs->dir);
                fvsum(testdir[1],gs->dir,vhor,r);
                fvsum(testdir[2],gs->dir,vhor,0.5*r);
                fvsum(testdir[5],testdir[2],midview.vup,-0.866*r);
                fvsum(testdir[2],testdir[2],midview.vup,0.866*r);
                fvsum(testdir[3],gs->dir,vhor,-r);
                fvsum(testdir[4],gs->dir,vhor,-0.5*r);
                fvsum(testdir[6],testdir[4],midview.vup,0.866*r);
                fvsum(testdir[4],testdir[4],midview.vup,-0.866*r);
                for (i = 0; i < 7; i++) {
                        normalize(testdir[i]);
                        p[i] = pow(posindex(testdir[i],mydir,midview.vup),-2.0);
                        if (p[i] <= FTINY) p[i] = 0.0;
                }
                r = 1-gs->dom/2./PI;
                omega = gs->dom*p[0];
                omega += (r*PI*(1+1/r/r)-2*PI)*(-p[0]+(p[1]+p[2])*0.5);
                omega += (2*PI-r*PI*(1+1/r/r))*(-p[0]-0.1667*(p[1]+p[3])
                          +0.3334*(p[2]+p[4]+p[5]+p[6]));

                sum += pow(gs->lum,1.6) * pow(omega,0.8) / 
                       (gd->indirect/PI + 0.07*sqrt(gs->dom)*gs->lum);
                n++;
        }
        if (n == 0)
                return(0.0);
        return( 10*log10(0.478*sum) );
}
 

double
brs_gi(gd)              /* compute BRS Glare Index */
struct glare_dir        *gd;
{
        register struct glare_src       *gs;
        FVECT   mydir;
        double  p;
        double  sum;
 
        spinvector(mydir, midview.vdir, midview.vup, gd->ang);
        sum = 0.0;
        for (gs = all_srcs; gs != NULL; gs = gs->next) {
                p = posindex(gs->dir, mydir, midview.vup);
                if (p <= FTINY)
                        continue;
                sum += pow(gs->lum/p,1.6) * pow(gs->dom,0.8);
        }
        if (sum <= FTINY)
                return(0.0);
        sum /= gd->indirect/PI;
        return(10*log10(0.478*sum));
}


double
guth_dgr(gd)            /* compute Guth discomfort glare rating */
struct glare_dir        *gd;
{
#define q(w)    (20.4*w+1.52*pow(w,.2)-.075)
        register struct glare_src       *gs;
        FVECT   mydir;
        double  p;
        double  sum;
        double  wtot, brsum;
        int     n;
 
        spinvector(mydir, midview.vdir, midview.vup, gd->ang);
        sum = wtot = brsum = 0.0; n = 0;
        for (gs = all_srcs; gs != NULL; gs = gs->next) {
                p = posindex(gs->dir, mydir, midview.vup);
                if (p <= FTINY)
                        continue;
                sum += gs->lum * q(gs->dom) / p;
                brsum += gs->lum * gs->dom;
                wtot += gs->dom;
                n++;
        }
        if (n == 0)
                return(0.0);
        return( pow(.5*sum/pow((brsum+(5.-wtot)*gd->indirect/PI)/5.,.44),
                        pow((double)n, -.0914) ) );
#undef q
}
 
 
extern double   erf(), erfc();
 
#ifndef M_SQRT2
#define M_SQRT2 1.41421356237309504880
#endif
 
#define norm_integral(z)        (1.-.5*erfc((z)/M_SQRT2))
 
 
double
guth_vcp(gd)            /* compute Guth visual comfort probability */
struct glare_dir        *gd;
{
        double  dgr;
 
        dgr = guth_dgr(gd);
        if (dgr <= FTINY)
                return(100.0);
        return(100.*norm_integral(6.374-1.3227*log(dgr)));
}
 
 
double
cie_cgi(gd)             /* compute CIE Glare Index */
struct glare_dir        *gd;
{
        register struct glare_src       *gs;
        FVECT   mydir;
        double  dillum;
        double  p;
        double  sum;
 
        spinvector(mydir, midview.vdir, midview.vup, gd->ang);
        sum = 0.0;
        for (gs = all_srcs; gs != NULL; gs = gs->next) {
                p = posindex(gs->dir, mydir, midview.vup);
                if (p <= FTINY)
                        continue;
                sum += gs->lum*gs->lum * gs->dom / (p*p);
        }
        if (sum <= FTINY)
                return(0.0);
        dillum = direct(gd);
        return(8.*log10(2.*sum*(1.+dillum/500.)/(dillum+gd->indirect)));
}


double
ugr(gd)         /* compute Unified Glare Rating */
struct glare_dir        *gd;
{
        register struct glare_src       *gs;
        FVECT   mydir;
        double  p;
        double  sum;
 
        spinvector(mydir, midview.vdir, midview.vup, gd->ang);
        sum = 0.0;
        for (gs = all_srcs; gs != NULL; gs = gs->next) {
                p = posindex(gs->dir, mydir, midview.vup);
                if (p <= FTINY)
                        continue;
                sum += gs->lum*gs->lum * gs->dom / (p*p);
        }
        if (sum <= FTINY)
                return(0.0);
        return(8.*log10(0.25*sum*PI/gd->indirect));
}
Revision:	2.4
Committed:	Thu Mar 24 11:06:59 1994 UTC (30 years, 1 month ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.3:	+150 -51 lines
Log Message:	Raphael added dgi, brs_gi, and ugr index calculations
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1991 Regents of the University of California */
2
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8	greg	1.9	* Compute Glare Index given by program name or -t option:
9	greg	1.1	*
10	greg	2.4	* dgi - Daylight Glare Index
11			* brs_gi - Building Research Station Glare Index (Petherbridge
12			* & Hopkinson)
13			* ugr - Unified Glare Rating System (Fischer)
14	greg	1.2	* guth_dgr - Guth discomfort glare rating
15			* guth_vcp - Guth visual comfort probability
16	greg	1.9	* cie_cgi - CIE Glare Index (1983, due to Einhorn)
17			* vert_dir - Direct vertical illuminance
18			* vert_ind - Indirect vertical illuminance (from input)
19			* vert_ill - Total vertical illuminance
20	greg	1.1	*
21			* 12 April 1991 Greg Ward EPFL
22	greg	2.4	* 19 April 1993 R. Compagnon EPFL (added dgi, brs_gi, ugr)
23	greg	1.1	*/
24	greg	2.4
25	greg	1.1	#include "standard.h"
26			#include "view.h"
27	greg	2.4
28	greg	1.1	extern double erfc();
29	greg	2.4
30	greg	1.1	double posindex();
31	greg	2.4
32	greg	1.9	double direct(), guth_dgr(), guth_vcp(), cie_cgi(),
33	greg	2.4	indirect(), total(), dgi(), brs_gi(), ugr();
34
35	greg	1.1	struct named_func {
36			char *name;
37			double (*func)();
38	greg	1.9	char *descrip;
39	greg	1.1	} all_funcs[] = {
40	greg	2.4	{"dgi", dgi, "Daylight Glare Index"},
41			{"brs_gi", brs_gi, "BRS Glare Index"},
42			{"ugr", ugr, "Unified Glare Rating"},
43	greg	1.9	{"guth_vcp", guth_vcp, "Guth Visual Comfort Probability"},
44			{"cie_cgi", cie_cgi, "CIE Glare Index (Einhorn)"},
45			{"guth_dgr", guth_dgr, "Guth Disability Glare Rating"},
46			{"vert_dir", direct, "Direct Vertical Illuminance"},
47			{"vert_ill", total, "Total Vertical Illuminance"},
48			{"vert_ind", indirect, "Indirect Vertical Illuminance"},
49	greg	1.1	{NULL}
50			};
51	greg	2.4
52	greg	1.1	struct glare_src {
53			FVECT dir; /* source direction */
54			double dom; /* solid angle */
55			double lum; /* average luminance */
56			struct glare_src *next;
57			} *all_srcs = NULL;
58	greg	2.4
59	greg	1.1	struct glare_dir {
60			double ang; /* angle (in radians) */
61			double indirect; /* indirect illuminance */
62			struct glare_dir *next;
63			} *all_dirs = NULL;
64	greg	2.4
65	greg	1.1	#define newp(type) (type *)malloc(sizeof(type))
66	greg	2.4
67	greg	1.1	char *progname;
68			int print_header = 1;
69	greg	2.4
70	greg	1.1	VIEW midview = STDVIEW;
71	greg	2.4
72	greg	1.4	int wrongformat = 0;
73	greg	2.4
74
75	greg	1.1	main(argc, argv)
76			int argc;
77			char *argv[];
78			{
79			extern char *rindex();
80			struct named_func *funp;
81			char *progtail;
82			int i;
83			/* get program name */
84			progname = argv[0];
85			progtail = rindex(progname, '/'); /* final component */
86			if (progtail == NULL)
87			progtail = progname;
88			else
89			progtail++;
90			/* get options */
91			for (i = 1; i < argc && argv[i][0] == '-'; i++)
92			switch (argv[i][1]) {
93			case 't':
94			progtail = argv[++i];
95			break;
96			case 'h':
97			print_header = 0;
98			break;
99			default:
100			goto userr;
101			}
102			if (i < argc-1)
103			goto userr;
104			if (i == argc-1) /* open file */
105			if (freopen(argv[i], "r", stdin) == NULL) {
106			perror(argv[i]);
107			exit(1);
108			}
109	greg	1.9	/* find and run calculation */
110	greg	1.1	for (funp = all_funcs; funp->name != NULL; funp++)
111			if (!strcmp(funp->name, progtail)) {
112	greg	1.9	init();
113			read_input();
114			if (print_header) {
115			printargs(i, argv, stdout);
116			putchar('\n');
117			}
118	greg	1.1	print_values(funp->func);
119			exit(0); /* we're done */
120			}
121			/* invalid function */
122			userr:
123	greg	1.9	fprintf(stderr, "Usage: %s -t type [-h] [input]\n", progname);
124			fprintf(stderr, "\twhere 'type' is one of the following:\n");
125			for (funp = all_funcs; funp->name != NULL; funp++)
126			fprintf(stderr, "\t%12s\t%s\n", funp->name, funp->descrip);
127	greg	1.1	exit(1);
128			}
129	greg	2.4
130
131	greg	1.1	headline(s) /* get line from header */
132			char *s;
133			{
134	greg	1.4	char fmt[32];
135	greg	2.4
136	greg	1.1	if (print_header) /* copy to output */
137			fputs(s, stdout);
138	greg	2.2	if (isview(s))
139			sscanview(&midview, s);
140	greg	1.4	else if (isformat(s)) {
141			formatval(fmt, s);
142	greg	1.6	wrongformat = strcmp(fmt, "ascii");
143	greg	1.4	}
144	greg	1.1	}
145	greg	2.4
146
147	greg	1.9	init() /* initialize calculation */
148			{
149			/* read header */
150			getheader(stdin, headline, NULL);
151			if (wrongformat) {
152			fprintf(stderr, "%s: bad input format\n", progname);
153			exit(1);
154			}
155			/* set view */
156			if (setview(&midview) != NULL) {
157			fprintf(stderr, "%s: bad view information in input\n",
158			progname);
159			exit(1);
160			}
161			}
162	greg	2.4
163
164	greg	1.1	read_input() /* read glare sources from stdin */
165			{
166			#define S_SEARCH 0
167			#define S_SOURCE 1
168			#define S_DIREC 2
169			int state = S_SEARCH;
170			char buf[128];
171			register struct glare_src *gs;
172			register struct glare_dir *gd;
173	greg	2.4
174	greg	1.1	while (fgets(buf, sizeof(buf), stdin) != NULL)
175			switch (state) {
176			case S_SEARCH:
177			if (!strcmp(buf, "BEGIN glare source\n"))
178			state = S_SOURCE;
179			else if (!strcmp(buf, "BEGIN indirect illuminance\n"))
180			state = S_DIREC;
181			break;
182			case S_SOURCE:
183			if (!strncmp(buf, "END", 3)) {
184			state = S_SEARCH;
185			break;
186			}
187			if ((gs = newp(struct glare_src)) == NULL)
188			goto memerr;
189			if (sscanf(buf, "%lf %lf %lf %lf %lf",
190			&gs->dir[0], &gs->dir[1], &gs->dir[2],
191			&gs->dom, &gs->lum) != 5)
192			goto readerr;
193	greg	1.2	normalize(gs->dir);
194	greg	1.1	gs->next = all_srcs;
195			all_srcs = gs;
196			break;
197			case S_DIREC:
198			if (!strncmp(buf, "END", 3)) {
199			state = S_SEARCH;
200			break;
201			}
202			if ((gd = newp(struct glare_dir)) == NULL)
203			goto memerr;
204			if (sscanf(buf, "%lf %lf",
205			&gd->ang, &gd->indirect) != 2)
206			goto readerr;
207			gd->ang = PI/180.0; / convert to radians */
208			gd->next = all_dirs;
209			all_dirs = gd;
210			break;
211			}
212			return;
213			memerr:
214			perror(progname);
215			exit(1);
216			readerr:
217			fprintf(stderr, "%s: read error on input\n", progname);
218			exit(1);
219			#undef S_SEARCH
220			#undef S_SOURCE
221			#undef S_DIREC
222			}
223	greg	2.4
224
225	greg	1.1	print_values(funp) /* print out calculations */
226			double (*funp)();
227			{
228			register struct glare_dir *gd;
229	greg	2.4
230	greg	1.1	for (gd = all_dirs; gd != NULL; gd = gd->next)
231			printf("%f\t%f\n", gd->ang(180.0/PI), (funp)(gd));
232			}
233	greg	2.4
234
235	greg	1.1	double
236	greg	1.9	direct(gd) /* compute direct vertical illuminance */
237	greg	1.1	struct glare_dir *gd;
238			{
239			FVECT mydir;
240			double d, dval;
241			register struct glare_src *gs;
242	greg	2.4
243	greg	1.1	spinvector(mydir, midview.vdir, midview.vup, gd->ang);
244			dval = 0.0;
245			for (gs = all_srcs; gs != NULL; gs = gs->next) {
246			d = DOT(mydir,gs->dir);
247			if (d > FTINY)
248			dval += d * gs->dom * gs->lum;
249			}
250			return(dval);
251	greg	1.9	}
252	greg	2.4
253
254	greg	1.9	double
255			indirect(gd) /* return indirect vertical illuminance */
256			struct glare_dir *gd;
257			{
258			return(gd->indirect);
259			}
260	greg	2.4
261
262	greg	1.9	double
263			total(gd) /* return total vertical illuminance */
264			struct glare_dir *gd;
265			{
266			return(direct(gd)+gd->indirect);
267	greg	1.1	}
268	greg	2.4
269
270	greg	1.1	/*
271			* posindex - compute glare position index from:
272			*
273			* Source Direction
274			* View Direction
275			* View Up Direction
276			*
277			* All vectors are assumed to be normalized.
278			* This function is an implementation of the method proposed by
279			* Robert Levin in his 1975 JIES article.
280	greg	1.5	* This calculation presumes the view direction and up vectors perpendicular.
281	greg	1.1	* We return a value less than zero for improper positions.
282			*/
283	greg	2.4
284	greg	1.1	double
285			posindex(sd, vd, vu) /* compute position index */
286			FVECT sd, vd, vu;
287			{
288			double sigma, tau;
289			double d;
290	greg	2.4
291	greg	1.1	d = DOT(sd,vd);
292			if (d <= 0.0)
293			return(-1.0);
294	greg	1.5	if (d >= 1.0)
295			return(1.0);
296	greg	1.1	sigma = acos(d) * (180./PI);
297	greg	2.4	d = fabs(DOT(sd,vu)/sqrt(1.0-d*d));
298	greg	1.5	if (d >= 1.0)
299			tau = 0.0;
300			else
301			tau = acos(d) * (180./PI);
302	greg	1.1	return( exp( sigma( (35.2 - tau.31889 - 1.22exp(-.22222tau))*1e-3
303			+ sigma(21. + tau(.26667 + tau-.002963))1e-5 )
304			) );
305			}
306	greg	2.4
307
308			double
309			dgi(gd) /* compute Daylight Glare Index */
310			struct glare_dir *gd;
311			{
312			register struct glare_src *gs;
313			FVECT mydir,testdir[7],vhor;
314			double r,omega,p[7],sum;
315			int i,n;
316
317			spinvector(mydir, midview.vdir, midview.vup, gd->ang);
318			sum = 0.0; n = 0;
319			for (gs = all_srcs; gs != NULL; gs = gs->next) {
320	greg	1.1
321	greg	2.4	/* compute 1/p^2 weighted solid angle of the source */
322			r = sqrt(1 - pow(1.-gs->dom/2./PI,2.));
323			fcross(vhor,gs->dir,midview.vup);
324			normalize(vhor);
325			VCOPY(testdir[0],gs->dir);
326			fvsum(testdir[1],gs->dir,vhor,r);
327			fvsum(testdir[2],gs->dir,vhor,0.5*r);
328			fvsum(testdir[5],testdir[2],midview.vup,-0.866*r);
329			fvsum(testdir[2],testdir[2],midview.vup,0.866*r);
330			fvsum(testdir[3],gs->dir,vhor,-r);
331			fvsum(testdir[4],gs->dir,vhor,-0.5*r);
332			fvsum(testdir[6],testdir[4],midview.vup,0.866*r);
333			fvsum(testdir[4],testdir[4],midview.vup,-0.866*r);
334			for (i = 0; i < 7; i++) {
335			normalize(testdir[i]);
336			p[i] = pow(posindex(testdir[i],mydir,midview.vup),-2.0);
337			if (p[i] <= FTINY) p[i] = 0.0;
338			}
339			r = 1-gs->dom/2./PI;
340			omega = gs->dom*p[0];
341			omega += (rPI(1+1/r/r)-2PI)(-p[0]+(p[1]+p[2])*0.5);
342			omega += (2PI-rPI(1+1/r/r))(-p[0]-0.1667*(p[1]+p[3])
343			+0.3334*(p[2]+p[4]+p[5]+p[6]));
344	greg	1.1
345	greg	2.4	sum += pow(gs->lum,1.6) * pow(omega,0.8) /
346			(gd->indirect/PI + 0.07sqrt(gs->dom)gs->lum);
347			n++;
348			}
349			if (n == 0)
350			return(0.0);
351			return( 10log10(0.478sum) );
352			}
353
354
355	greg	1.1	double
356	greg	2.4	brs_gi(gd) /* compute BRS Glare Index */
357			struct glare_dir *gd;
358			{
359			register struct glare_src *gs;
360			FVECT mydir;
361			double p;
362			double sum;
363
364			spinvector(mydir, midview.vdir, midview.vup, gd->ang);
365			sum = 0.0;
366			for (gs = all_srcs; gs != NULL; gs = gs->next) {
367			p = posindex(gs->dir, mydir, midview.vup);
368			if (p <= FTINY)
369			continue;
370			sum += pow(gs->lum/p,1.6) * pow(gs->dom,0.8);
371			}
372			if (sum <= FTINY)
373			return(0.0);
374			sum /= gd->indirect/PI;
375			return(10log10(0.478sum));
376			}
377
378
379			double
380	greg	1.2	guth_dgr(gd) /* compute Guth discomfort glare rating */
381	greg	1.1	struct glare_dir *gd;
382			{
383			#define q(w) (20.4w+1.52pow(w,.2)-.075)
384			register struct glare_src *gs;
385	greg	1.7	FVECT mydir;
386	greg	1.1	double p;
387			double sum;
388	greg	1.3	double wtot, brsum;
389	greg	1.1	int n;
390	greg	2.4
391	greg	1.7	spinvector(mydir, midview.vdir, midview.vup, gd->ang);
392	greg	1.3	sum = wtot = brsum = 0.0; n = 0;
393	greg	1.1	for (gs = all_srcs; gs != NULL; gs = gs->next) {
394	greg	1.7	p = posindex(gs->dir, mydir, midview.vup);
395	greg	1.1	if (p <= FTINY)
396			continue;
397			sum += gs->lum * q(gs->dom) / p;
398	greg	1.3	brsum += gs->lum * gs->dom;
399			wtot += gs->dom;
400	greg	1.1	n++;
401			}
402			if (n == 0)
403			return(0.0);
404	greg	1.8	return( pow(.5sum/pow((brsum+(5.-wtot)gd->indirect/PI)/5.,.44),
405	greg	1.1	pow((double)n, -.0914) ) );
406			#undef q
407			}
408	greg	2.4
409
410	greg	1.1	extern double erf(), erfc();
411	greg	2.4
412	greg	1.1	#ifndef M_SQRT2
413			#define M_SQRT2 1.41421356237309504880
414			#endif
415	greg	2.4
416	greg	1.1	#define norm_integral(z) (1.-.5*erfc((z)/M_SQRT2))
417	greg	2.4
418
419	greg	1.1	double
420	greg	1.2	guth_vcp(gd) /* compute Guth visual comfort probability */
421	greg	1.1	struct glare_dir *gd;
422			{
423	greg	1.7	double dgr;
424	greg	2.4
425	greg	1.7	dgr = guth_dgr(gd);
426			if (dgr <= FTINY)
427			return(100.0);
428			return(100.norm_integral(6.374-1.3227log(dgr)));
429	greg	1.8	}
430	greg	2.4
431
432	greg	1.8	double
433			cie_cgi(gd) /* compute CIE Glare Index */
434			struct glare_dir *gd;
435			{
436			register struct glare_src *gs;
437			FVECT mydir;
438			double dillum;
439			double p;
440			double sum;
441	greg	2.4
442	greg	1.8	spinvector(mydir, midview.vdir, midview.vup, gd->ang);
443			sum = 0.0;
444			for (gs = all_srcs; gs != NULL; gs = gs->next) {
445			p = posindex(gs->dir, mydir, midview.vup);
446			if (p <= FTINY)
447			continue;
448			sum += gs->lumgs->lum gs->dom / (p*p);
449			}
450			if (sum <= FTINY)
451			return(0.0);
452			dillum = direct(gd);
453			return(8.log10(2.sum*(1.+dillum/500.)/(dillum+gd->indirect)));
454	greg	2.4	}
455
456
457			double
458			ugr(gd) /* compute Unified Glare Rating */
459			struct glare_dir *gd;
460			{
461			register struct glare_src *gs;
462			FVECT mydir;
463			double p;
464			double sum;
465
466			spinvector(mydir, midview.vdir, midview.vup, gd->ang);
467			sum = 0.0;
468			for (gs = all_srcs; gs != NULL; gs = gs->next) {
469			p = posindex(gs->dir, mydir, midview.vup);
470			if (p <= FTINY)
471			continue;
472			sum += gs->lumgs->lum gs->dom / (p*p);
473			}
474			if (sum <= FTINY)
475			return(0.0);
476			return(8.log10(0.25sum*PI/gd->indirect));
477	greg	1.1	}