src/gen/gensky.c

#ifndef lint
static const char       RCSid[] = "$Id: gensky.c,v 2.25 2010/12/08 21:22:33 greg Exp $";
#endif
/*
 *  gensky.c - program to generate sky functions.
 *              Our zenith is along the Z-axis, the X-axis
 *              points east, and the Y-axis points north.
 *              Radiance is in watts/steradian/sq. meter.
 *
 *     3/26/86
 */

#include  <stdio.h>
#include  <stdlib.h>
#include  <string.h>
#include  <math.h>
#include  <ctype.h>
#include  "sun.h"
#include  "color.h"

#ifndef  PI
#define  PI             3.14159265358979323846
#endif

#define  DOT(v1,v2)     (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2])

#define  S_CLEAR        1
#define  S_OVER         2
#define  S_UNIF         3
#define  S_INTER        4

#define  overcast       ((skytype==S_OVER)|(skytype==S_UNIF))

double  normsc();

#undef  toupper
#define  toupper(c)     ((c) & ~0x20)   /* ASCII trick to convert case */

                                        /* European and North American zones */
struct {
        char    zname[8];       /* time zone name (all caps) */
        float   zmer;           /* standard meridian */
} tzone[] = {
        {"YST", 135}, {"YDT", 120},
        {"PST", 120}, {"PDT", 105},
        {"MST", 105}, {"MDT", 90},
        {"CST", 90}, {"CDT", 75},
        {"EST", 75}, {"EDT", 60},
        {"AST", 60}, {"ADT", 45},
        {"NST", 52.5}, {"NDT", 37.5},
        {"GMT", 0}, {"BST", -15},
        {"CET", -15}, {"CEST", -30},
        {"EET", -30}, {"EEST", -45},
        {"AST", -45}, {"ADT", -60},
        {"GST", -60}, {"GDT", -75},
        {"IST", -82.5}, {"IDT", -97.5},
        {"JST", -135}, {"NDT", -150},
        {"NZST", -180}, {"NZDT", -195},
        {"", 0}
};
                                        /* required values */
int  month, day;                                /* date */
double  hour;                                   /* time */
int  tsolar;                                    /* 0=standard, 1=solar */
double  altitude, azimuth;                      /* or solar angles */
                                        /* default values */
int  skytype = S_CLEAR;                         /* sky type */
int  dosun = 1;
double  zenithbr = 0.0;
int     u_zenith = 0;                           /* -1=irradiance, 1=radiance */
double  turbidity = 2.45;
double  gprefl = 0.2;
                                        /* computed values */
double  sundir[3];
double  groundbr;
double  F2;
double  solarbr = 0.0;
int     u_solar = 0;                            /* -1=irradiance, 1=radiance */

char  *progname;
char  errmsg[128];

void computesky(void);
void printsky(void);
void printdefaults(void);
void userror(char  *msg);
double normsc(void);
int cvthour(char  *hs);
void printhead(int  ac, char  **av);


int
main(
        int  argc,
        char  *argv[]
)
{
        int  got_meridian = 0;
        int  i;

        progname = argv[0];
        if (argc == 2 && !strcmp(argv[1], "-defaults")) {
                printdefaults();
                exit(0);
        }
        if (argc < 4)
                userror("arg count");
        if (!strcmp(argv[1], "-ang")) {
                altitude = atof(argv[2]) * (PI/180);
                azimuth = atof(argv[3]) * (PI/180);
                month = 0;
        } else {
                month = atoi(argv[1]);
                if (month < 1 || month > 12)
                        userror("bad month");
                day = atoi(argv[2]);
                if (day < 1 || day > 31)
                        userror("bad day");
                got_meridian = cvthour(argv[3]);
        }
        for (i = 4; i < argc; i++)
                if (argv[i][0] == '-' || argv[i][0] == '+')
                        switch (argv[i][1]) {
                        case 's':
                                skytype = S_CLEAR;
                                dosun = argv[i][0] == '+';
                                break;
                        case 'r':
                        case 'R':
                                u_solar = argv[i][1]=='R' ? -1 : 1;
                                solarbr = atof(argv[++i]);
                                break;
                        case 'c':
                                skytype = S_OVER;
                                break;
                        case 'u':
                                skytype = S_UNIF;
                                break;
                        case 'i':
                                skytype = S_INTER;
                                dosun = argv[i][0] == '+';
                                break;
                        case 't':
                                turbidity = atof(argv[++i]);
                                break;
                        case 'b':
                        case 'B':
                                u_zenith = argv[i][1]=='B' ? -1 : 1;
                                zenithbr = atof(argv[++i]);
                                break;
                        case 'g':
                                gprefl = atof(argv[++i]);
                                break;
                        case 'a':
                                s_latitude = atof(argv[++i]) * (PI/180);
                                break;
                        case 'o':
                                s_longitude = atof(argv[++i]) * (PI/180);
                                break;
                        case 'm':
                                if (got_meridian) {
                                        ++i;
                                        break;          /* time overrides */
                                }
                                s_meridian = atof(argv[++i]) * (PI/180);
                                break;
                        default:
                                sprintf(errmsg, "unknown option: %s", argv[i]);
                                userror(errmsg);
                        }
                else
                        userror("bad option");

        if (month && !tsolar && fabs(s_meridian-s_longitude) > 45*PI/180)
                fprintf(stderr,
        "%s: warning - %.1f hours btwn. standard meridian and longitude\n",
                        progname, (s_longitude-s_meridian)*12/PI);

        printhead(argc, argv);

        computesky();
        printsky();

        exit(0);
}


void
computesky(void)                        /* compute sky parameters */
{
        double  normfactor;
                                        /* compute solar direction */
        if (month) {                    /* from date and time */
                int  jd;
                double  sd, st;

                jd = jdate(month, day);         /* Julian date */
                sd = sdec(jd);                  /* solar declination */
                if (tsolar)                     /* solar time */
                        st = hour;
                else
                        st = hour + stadj(jd);
                altitude = salt(sd, st);
                azimuth = sazi(sd, st);
                printf("# Local solar time: %.2f\n", st);
                printf("# Solar altitude and azimuth: %.1f %.1f\n",
                                180./PI*altitude, 180./PI*azimuth);
        }
        if (!overcast && altitude > 87.*PI/180.) {
                fprintf(stderr,
"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n",
                                progname);
                printf(
"# warning - sun too close to zenith, reducing altitude to 87 degrees\n");
                altitude = 87.*PI/180.;
        }
        sundir[0] = -sin(azimuth)*cos(altitude);
        sundir[1] = -cos(azimuth)*cos(altitude);
        sundir[2] = sin(altitude);

                                        /* Compute normalization factor */
        switch (skytype) {
        case S_UNIF:
                normfactor = 1.0;
                break;
        case S_OVER:
                normfactor = 0.777778;
                break;
        case S_CLEAR:
                F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) +
                                0.45*sundir[2]*sundir[2]);
                normfactor = normsc()/F2/PI;
                break;
        case S_INTER:
                F2 = (2.739 + .9891*sin(.3119+2.6*altitude)) *
                        exp(-(PI/2.0-altitude)*(.4441+1.48*altitude));
                normfactor = normsc()/F2/PI;
                break;
        }
                                        /* Compute zenith brightness */
        if (u_zenith == -1)
                zenithbr /= normfactor*PI;
        else if (u_zenith == 0) {
                if (overcast)
                        zenithbr = 8.6*sundir[2] + .123;
                else
                        zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
                if (skytype == S_INTER)
                        zenithbr = (zenithbr + 8.6*sundir[2] + .123)/2.0;
                if (zenithbr < 0.0)
                        zenithbr = 0.0;
                else
                        zenithbr *= 1000.0/SKYEFFICACY;
        }
                                        /* Compute horizontal radiance */
        groundbr = zenithbr*normfactor;
        printf("# Ground ambient level: %.1f\n", groundbr);
        if (!overcast && sundir[2] > 0.0 && (!u_solar || solarbr > 0.0)) {
                if (u_solar == -1)
                        solarbr /= 6e-5*sundir[2];
                else if (u_solar == 0) {
                        solarbr = 1.5e9/SUNEFFICACY *
                        (1.147 - .147/(sundir[2]>.16?sundir[2]:.16));
                        if (skytype == S_INTER)
                                solarbr *= 0.15;        /* fudge factor! */
                }
                groundbr += 6e-5/PI*solarbr*sundir[2];
        } else
                dosun = 0;
        groundbr *= gprefl;
}


void
printsky(void)                  /* print out sky */
{
        if (dosun) {
                printf("\nvoid light solar\n");
                printf("0\n0\n");
                printf("3 %.2e %.2e %.2e\n", solarbr, solarbr, solarbr);
                printf("\nsolar source sun\n");
                printf("0\n0\n");
                printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]);
        }
        
        printf("\nvoid brightfunc skyfunc\n");
        printf("2 skybr skybright.cal\n");
        printf("0\n");
        if (overcast)
                printf("3 %d %.2e %.2e\n", skytype, zenithbr, groundbr);
        else
                printf("7 %d %.2e %.2e %.2e %f %f %f\n",
                                skytype, zenithbr, groundbr, F2,
                                sundir[0], sundir[1], sundir[2]);
}


void
printdefaults(void)                     /* print default values */
{
        switch (skytype) {
        case S_OVER:
                printf("-c\t\t\t\t# Cloudy sky\n");
                break;
        case S_UNIF:
                printf("-u\t\t\t\t# Uniform cloudy sky\n");
                break;
        case S_INTER:
                if (dosun)
                        printf("+i\t\t\t\t# Intermediate sky with sun\n");
                else
                        printf("-i\t\t\t\t# Intermediate sky without sun\n");
                break;
        case S_CLEAR:
                if (dosun)
                        printf("+s\t\t\t\t# Sunny sky with sun\n");
                else
                        printf("-s\t\t\t\t# Sunny sky without sun\n");
                break;
        }
        printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl);
        if (zenithbr > 0.0)
                printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr);
        else
                printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity);
        printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI));
        printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI));
        printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI));
}


void
userror(                        /* print usage error and quit */
        char  *msg
)
{
        if (msg != NULL)
                fprintf(stderr, "%s: Use error - %s\n", progname, msg);
        fprintf(stderr, "Usage: %s month day hour [options]\n", progname);
        fprintf(stderr, "   Or: %s -ang altitude azimuth [options]\n", progname);
        fprintf(stderr, "   Or: %s -defaults\n", progname);
        exit(1);
}


double
normsc(void)                    /* compute normalization factor (E0*F2/L0) */
{
        static double  nfc[2][5] = {
                                /* clear sky approx. */
                {2.766521, 0.547665, -0.369832, 0.009237, 0.059229},
                                /* intermediate sky approx. */
                {3.5556, -2.7152, -1.3081, 1.0660, 0.60227},
        };
        double  *nf;
        double  x, nsc;
        int  i;
                                        /* polynomial approximation */
        nf = nfc[skytype==S_INTER];
        x = (altitude - PI/4.0)/(PI/4.0);
        nsc = nf[i=4];
        while (i--)
                nsc = nsc*x + nf[i];

        return(nsc);
}


int
cvthour(                        /* convert hour string */
        char  *hs
)
{
        char  *cp = hs;
        int     i, j;

        if ( (tsolar = *cp == '+') ) cp++;              /* solar time? */
        while (isdigit(*cp)) cp++;
        if (*cp == ':')
                hour = atoi(hs) + atoi(++cp)/60.0;
        else {
                hour = atof(hs);
                if (*cp == '.') cp++;
        }
        while (isdigit(*cp)) cp++;
        if (!*cp)
                return(0);
        if (tsolar || !isalpha(*cp)) {
                fprintf(stderr, "%s: bad time format: %s\n", progname, hs);
                exit(1);
        }
        i = 0;
        do {
                for (j = 0; cp[j]; j++)
                        if (toupper(cp[j]) != tzone[i].zname[j])
                                break;
                if (!cp[j] && !tzone[i].zname[j]) {
                        s_meridian = tzone[i].zmer * (PI/180);
                        return(1);
                }
        } while (tzone[i++].zname[0]);

        fprintf(stderr, "%s: unknown time zone: %s\n", progname, cp);
        fprintf(stderr, "Known time zones:\n\t%s", tzone[0].zname);
        for (i = 1; tzone[i].zname[0]; i++)
                fprintf(stderr, " %s", tzone[i].zname);
        putc('\n', stderr);
        exit(1);
}


void
printhead(              /* print command header */
        int  ac,
        char  **av
)
{
        putchar('#');
        while (ac--) {
                putchar(' ');
                fputs(*av++, stdout);
        }
        putchar('\n');
}
Revision:	2.26
Committed:	Wed Jul 30 17:30:27 2014 UTC (9 years, 9 months ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad5R2, rad4R2P2, rad5R0, rad5R1, rad4R2, rad4R2P1
Changes since 2.25:	+13 -22 lines
Log Message:	Improved use of sun.h
#	User	Rev	Content
1	greg	1.1	#ifndef lint
2	greg	2.26	static const char RCSid[] = "$Id: gensky.c,v 2.25 2010/12/08 21:22:33 greg Exp $";
3	greg	1.1	#endif
4			/*
5			* gensky.c - program to generate sky functions.
6			* Our zenith is along the Z-axis, the X-axis
7			* points east, and the Y-axis points north.
8			* Radiance is in watts/steradian/sq. meter.
9			*
10			* 3/26/86
11			*/
12
13			#include <stdio.h>
14	greg	2.20	#include <stdlib.h>
15			#include <string.h>
16	greg	1.1	#include <math.h>
17	greg	2.17	#include <ctype.h>
18	greg	2.26	#include "sun.h"
19	greg	1.6	#include "color.h"
20	greg	1.1
21	greg	2.17	#ifndef PI
22			#define PI 3.14159265358979323846
23			#endif
24	greg	1.1
25			#define DOT(v1,v2) (v1[0]v2[0]+v1[1]v2[1]+v1[2]*v2[2])
26
27	greg	2.13	#define S_CLEAR 1
28			#define S_OVER 2
29			#define S_UNIF 3
30			#define S_INTER 4
31
32	schorsch	2.21	#define overcast ((skytype==S_OVER)\|(skytype==S_UNIF))
33	greg	2.13
34	greg	1.1	double normsc();
35	greg	2.17
36			#undef toupper
37			#define toupper(c) ((c) & ~0x20) /* ASCII trick to convert case */
38
39			/* European and North American zones */
40			struct {
41			char zname[8]; /* time zone name (all caps) */
42			float zmer; /* standard meridian */
43			} tzone[] = {
44	schorsch	2.22	{"YST", 135}, {"YDT", 120},
45			{"PST", 120}, {"PDT", 105},
46			{"MST", 105}, {"MDT", 90},
47			{"CST", 90}, {"CDT", 75},
48			{"EST", 75}, {"EDT", 60},
49			{"AST", 60}, {"ADT", 45},
50			{"NST", 52.5}, {"NDT", 37.5},
51			{"GMT", 0}, {"BST", -15},
52			{"CET", -15}, {"CEST", -30},
53			{"EET", -30}, {"EEST", -45},
54			{"AST", -45}, {"ADT", -60},
55			{"GST", -60}, {"GDT", -75},
56			{"IST", -82.5}, {"IDT", -97.5},
57			{"JST", -135}, {"NDT", -150},
58			{"NZST", -180}, {"NZDT", -195},
59			{"", 0}
60	greg	2.17	};
61	greg	1.1	/* required values */
62	greg	2.3	int month, day; /* date */
63	greg	2.5	double hour; /* time */
64			int tsolar; /* 0=standard, 1=solar */
65	greg	2.3	double altitude, azimuth; /* or solar angles */
66	greg	1.1	/* default values */
67	greg	2.13	int skytype = S_CLEAR; /* sky type */
68	greg	1.1	int dosun = 1;
69	greg	2.12	double zenithbr = 0.0;
70			int u_zenith = 0; /* -1=irradiance, 1=radiance */
71	greg	2.24	double turbidity = 2.45;
72	greg	1.1	double gprefl = 0.2;
73			/* computed values */
74			double sundir[3];
75			double groundbr;
76			double F2;
77	greg	2.12	double solarbr = 0.0;
78			int u_solar = 0; /* -1=irradiance, 1=radiance */
79	greg	1.1
80			char *progname;
81			char errmsg[128];
82
83	schorsch	2.22	void computesky(void);
84			void printsky(void);
85			void printdefaults(void);
86			void userror(char *msg);
87			double normsc(void);
88	greg	2.23	int cvthour(char *hs);
89	greg	2.26	void printhead(int ac, char **av);
90	schorsch	2.22
91	greg	1.1
92	schorsch	2.22	int
93	greg	2.26	main(
94			int argc,
95			char *argv[]
96			)
97	greg	1.1	{
98	greg	2.23	int got_meridian = 0;
99	greg	1.1	int i;
100
101			progname = argv[0];
102			if (argc == 2 && !strcmp(argv[1], "-defaults")) {
103			printdefaults();
104			exit(0);
105			}
106			if (argc < 4)
107			userror("arg count");
108	greg	2.3	if (!strcmp(argv[1], "-ang")) {
109			altitude = atof(argv[2]) * (PI/180);
110			azimuth = atof(argv[3]) * (PI/180);
111			month = 0;
112			} else {
113			month = atoi(argv[1]);
114	greg	2.6	if (month < 1 \|\| month > 12)
115			userror("bad month");
116	greg	2.3	day = atoi(argv[2]);
117	greg	2.6	if (day < 1 \|\| day > 31)
118			userror("bad day");
119	greg	2.23	got_meridian = cvthour(argv[3]);
120	greg	2.3	}
121	greg	1.1	for (i = 4; i < argc; i++)
122			if (argv[i][0] == '-' \|\| argv[i][0] == '+')
123			switch (argv[i][1]) {
124			case 's':
125	greg	2.13	skytype = S_CLEAR;
126	greg	1.1	dosun = argv[i][0] == '+';
127			break;
128	greg	2.8	case 'r':
129	greg	2.12	case 'R':
130			u_solar = argv[i][1]=='R' ? -1 : 1;
131	greg	2.8	solarbr = atof(argv[++i]);
132			break;
133	greg	1.1	case 'c':
134	greg	2.13	skytype = S_OVER;
135	greg	1.1	break;
136	greg	2.13	case 'u':
137			skytype = S_UNIF;
138			break;
139			case 'i':
140			skytype = S_INTER;
141			dosun = argv[i][0] == '+';
142			break;
143	greg	1.1	case 't':
144			turbidity = atof(argv[++i]);
145			break;
146			case 'b':
147	greg	2.12	case 'B':
148			u_zenith = argv[i][1]=='B' ? -1 : 1;
149	greg	1.1	zenithbr = atof(argv[++i]);
150			break;
151			case 'g':
152			gprefl = atof(argv[++i]);
153			break;
154			case 'a':
155			s_latitude = atof(argv[++i]) * (PI/180);
156			break;
157			case 'o':
158			s_longitude = atof(argv[++i]) * (PI/180);
159			break;
160			case 'm':
161	greg	2.23	if (got_meridian) {
162			++i;
163			break; /* time overrides */
164			}
165	greg	1.1	s_meridian = atof(argv[++i]) * (PI/180);
166			break;
167			default:
168			sprintf(errmsg, "unknown option: %s", argv[i]);
169			userror(errmsg);
170			}
171			else
172			userror("bad option");
173	greg	1.5
174	greg	2.25	if (month && !tsolar && fabs(s_meridian-s_longitude) > 45*PI/180)
175	greg	1.5	fprintf(stderr,
176	greg	2.25	"%s: warning - %.1f hours btwn. standard meridian and longitude\n",
177	greg	1.5	progname, (s_longitude-s_meridian)*12/PI);
178	greg	1.1
179			printhead(argc, argv);
180
181			computesky();
182			printsky();
183	greg	2.15
184			exit(0);
185	greg	1.1	}
186
187
188	schorsch	2.22	void
189			computesky(void) /* compute sky parameters */
190	greg	1.1	{
191	greg	2.12	double normfactor;
192	greg	1.1	/* compute solar direction */
193	greg	2.3	if (month) { /* from date and time */
194			int jd;
195			double sd, st;
196
197			jd = jdate(month, day); /* Julian date */
198			sd = sdec(jd); /* solar declination */
199	greg	2.5	if (tsolar) /* solar time */
200			st = hour;
201			else
202			st = hour + stadj(jd);
203	greg	2.3	altitude = salt(sd, st);
204			azimuth = sazi(sd, st);
205	greg	2.17	printf("# Local solar time: %.2f\n", st);
206	greg	2.13	printf("# Solar altitude and azimuth: %.1f %.1f\n",
207	greg	2.11	180./PIaltitude, 180./PIazimuth);
208	greg	2.9	}
209	greg	2.13	if (!overcast && altitude > 87.*PI/180.) {
210	greg	2.9	fprintf(stderr,
211			"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n",
212			progname);
213			printf(
214			"# warning - sun too close to zenith, reducing altitude to 87 degrees\n");
215			altitude = 87.*PI/180.;
216	greg	2.3	}
217	greg	1.1	sundir[0] = -sin(azimuth)*cos(altitude);
218			sundir[1] = -cos(azimuth)*cos(altitude);
219			sundir[2] = sin(altitude);
220
221	greg	2.12	/* Compute normalization factor */
222	greg	2.13	switch (skytype) {
223			case S_UNIF:
224	greg	2.12	normfactor = 1.0;
225	greg	2.13	break;
226			case S_OVER:
227	greg	2.12	normfactor = 0.777778;
228	greg	2.13	break;
229			case S_CLEAR:
230	greg	2.12	F2 = 0.274(0.91 + 10.0exp(-3.0*(PI/2.0-altitude)) +
231			0.45sundir[2]sundir[2]);
232	greg	2.13	normfactor = normsc()/F2/PI;
233			break;
234			case S_INTER:
235			F2 = (2.739 + .9891sin(.3119+2.6altitude)) *
236			exp(-(PI/2.0-altitude)(.4441+1.48altitude));
237			normfactor = normsc()/F2/PI;
238			break;
239	greg	2.12	}
240	greg	1.1	/* Compute zenith brightness */
241	greg	2.12	if (u_zenith == -1)
242			zenithbr /= normfactor*PI;
243			else if (u_zenith == 0) {
244	greg	2.13	if (overcast)
245	greg	1.1	zenithbr = 8.6*sundir[2] + .123;
246	greg	2.12	else
247	greg	1.1	zenithbr = (1.376turbidity-1.81)tan(altitude)+0.38;
248	greg	2.13	if (skytype == S_INTER)
249			zenithbr = (zenithbr + 8.6*sundir[2] + .123)/2.0;
250	greg	2.12	if (zenithbr < 0.0)
251			zenithbr = 0.0;
252			else
253	greg	1.6	zenithbr *= 1000.0/SKYEFFICACY;
254	greg	2.12	}
255	greg	1.1	/* Compute horizontal radiance */
256	greg	2.12	groundbr = zenithbr*normfactor;
257	greg	2.13	printf("# Ground ambient level: %.1f\n", groundbr);
258	greg	2.14	if (!overcast && sundir[2] > 0.0 && (!u_solar \|\| solarbr > 0.0)) {
259	greg	2.12	if (u_solar == -1)
260			solarbr /= 6e-5*sundir[2];
261	greg	2.13	else if (u_solar == 0) {
262	greg	2.12	solarbr = 1.5e9/SUNEFFICACY *
263			(1.147 - .147/(sundir[2]>.16?sundir[2]:.16));
264	greg	2.13	if (skytype == S_INTER)
265			solarbr = 0.15; / fudge factor! */
266			}
267	greg	2.12	groundbr += 6e-5/PIsolarbrsundir[2];
268			} else
269			dosun = 0;
270	greg	1.1	groundbr *= gprefl;
271			}
272
273
274	schorsch	2.22	void
275			printsky(void) /* print out sky */
276	greg	1.1	{
277			if (dosun) {
278			printf("\nvoid light solar\n");
279			printf("0\n0\n");
280	greg	1.6	printf("3 %.2e %.2e %.2e\n", solarbr, solarbr, solarbr);
281	greg	1.1	printf("\nsolar source sun\n");
282			printf("0\n0\n");
283			printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]);
284			}
285
286			printf("\nvoid brightfunc skyfunc\n");
287	greg	2.13	printf("2 skybr skybright.cal\n");
288	greg	1.1	printf("0\n");
289	greg	2.13	if (overcast)
290			printf("3 %d %.2e %.2e\n", skytype, zenithbr, groundbr);
291	greg	1.1	else
292	greg	2.13	printf("7 %d %.2e %.2e %.2e %f %f %f\n",
293			skytype, zenithbr, groundbr, F2,
294			sundir[0], sundir[1], sundir[2]);
295	greg	1.1	}
296
297
298	schorsch	2.22	void
299			printdefaults(void) /* print default values */
300	greg	1.1	{
301	greg	2.13	switch (skytype) {
302			case S_OVER:
303	greg	1.1	printf("-c\t\t\t\t# Cloudy sky\n");
304	greg	2.13	break;
305			case S_UNIF:
306			printf("-u\t\t\t\t# Uniform cloudy sky\n");
307			break;
308			case S_INTER:
309			if (dosun)
310			printf("+i\t\t\t\t# Intermediate sky with sun\n");
311			else
312			printf("-i\t\t\t\t# Intermediate sky without sun\n");
313			break;
314			case S_CLEAR:
315			if (dosun)
316			printf("+s\t\t\t\t# Sunny sky with sun\n");
317			else
318			printf("-s\t\t\t\t# Sunny sky without sun\n");
319			break;
320			}
321	greg	1.1	printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl);
322			if (zenithbr > 0.0)
323			printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr);
324			else
325			printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity);
326			printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI));
327			printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI));
328			printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI));
329			}
330
331
332	schorsch	2.22	void
333			userror( /* print usage error and quit */
334			char *msg
335			)
336	greg	1.1	{
337			if (msg != NULL)
338			fprintf(stderr, "%s: Use error - %s\n", progname, msg);
339			fprintf(stderr, "Usage: %s month day hour [options]\n", progname);
340	greg	2.3	fprintf(stderr, " Or: %s -ang altitude azimuth [options]\n", progname);
341	greg	1.1	fprintf(stderr, " Or: %s -defaults\n", progname);
342			exit(1);
343			}
344
345
346			double
347	schorsch	2.22	normsc(void) /* compute normalization factor (E0F2/L0) /
348	greg	1.1	{
349	greg	2.13	static double nfc[2][5] = {
350			/* clear sky approx. */
351			{2.766521, 0.547665, -0.369832, 0.009237, 0.059229},
352			/* intermediate sky approx. */
353			{3.5556, -2.7152, -1.3081, 1.0660, 0.60227},
354			};
355	greg	2.26	double *nf;
356	greg	1.1	double x, nsc;
357	greg	2.26	int i;
358	greg	1.1	/* polynomial approximation */
359	greg	2.13	nf = nfc[skytype==S_INTER];
360			x = (altitude - PI/4.0)/(PI/4.0);
361			nsc = nf[i=4];
362			while (i--)
363	greg	1.1	nsc = nsc*x + nf[i];
364
365			return(nsc);
366	greg	2.16	}
367
368
369	greg	2.23	int
370	schorsch	2.22	cvthour( /* convert hour string */
371			char *hs
372			)
373	greg	2.16	{
374	greg	2.26	char *cp = hs;
375			int i, j;
376	greg	2.16
377	schorsch	2.21	if ( (tsolar = cp == '+') ) cp++; / solar time? */
378	greg	2.17	while (isdigit(*cp)) cp++;
379			if (*cp == ':')
380			hour = atoi(hs) + atoi(++cp)/60.0;
381			else {
382	greg	2.16	hour = atof(hs);
383	greg	2.17	if (*cp == '.') cp++;
384			}
385			while (isdigit(*cp)) cp++;
386			if (!*cp)
387	greg	2.23	return(0);
388	greg	2.17	if (tsolar \|\| !isalpha(*cp)) {
389			fprintf(stderr, "%s: bad time format: %s\n", progname, hs);
390			exit(1);
391			}
392			i = 0;
393			do {
394			for (j = 0; cp[j]; j++)
395			if (toupper(cp[j]) != tzone[i].zname[j])
396			break;
397			if (!cp[j] && !tzone[i].zname[j]) {
398			s_meridian = tzone[i].zmer * (PI/180);
399	greg	2.23	return(1);
400	greg	2.17	}
401			} while (tzone[i++].zname[0]);
402
403			fprintf(stderr, "%s: unknown time zone: %s\n", progname, cp);
404			fprintf(stderr, "Known time zones:\n\t%s", tzone[0].zname);
405			for (i = 1; tzone[i].zname[0]; i++)
406			fprintf(stderr, " %s", tzone[i].zname);
407			putc('\n', stderr);
408			exit(1);
409	greg	1.1	}
410
411
412	schorsch	2.22	void
413			printhead( /* print command header */
414	greg	2.26	int ac,
415			char **av
416	schorsch	2.22	)
417	greg	1.1	{
418			putchar('#');
419			while (ac--) {
420			putchar(' ');
421			fputs(*av++, stdout);
422			}
423			putchar('\n');
424			}