src/gen/gensky.c

/* Copyright (c) 1992 Regents of the University of California */

#ifndef lint
static char SCCSid[] = "$SunId$ LBL";
#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  <math.h>

#include  "color.h"

extern char  *strcpy(), *strcat(), *malloc();
extern double  stadj(), sdec(), sazi(), salt();

#define  PI             3.141592654

#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();
                                        /* sun calculation constants */
extern double  s_latitude;
extern double  s_longitude;
extern double  s_meridian;
                                        /* 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 = 2.75;
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];


main(argc, argv)
int  argc;
char  *argv[];
{
        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");
                hour = atof(argv[3]);
                if (hour < 0 || hour >= 24)
                        userror("bad hour");
                tsolar = argv[3][0] == '+';
        }
        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;
                                dosun = 0;
                                break;
                        case 'u':
                                skytype = S_UNIF;
                                dosun = 0;
                                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':
                                s_meridian = atof(argv[++i]) * (PI/180);
                                break;
                        default:
                                sprintf(errmsg, "unknown option: %s", argv[i]);
                                userror(errmsg);
                        }
                else
                        userror("bad option");

        if (fabs(s_meridian-s_longitude) > 30*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();
}


computesky()                    /* 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("# 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 (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;
}


printsky()                      /* 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]);
}


printdefaults()                 /* 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));
}


userror(msg)                    /* 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()                        /* 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},
        };
        register double  *nf;
        double  x, nsc;
        register 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);
}


printhead(ac, av)               /* print command header */
register int  ac;
register char  **av;
{
        putchar('#');
        while (ac--) {
                putchar(' ');
                fputs(*av++, stdout);
        }
        putchar('\n');
}
Revision:	2.13
Committed:	Fri Nov 5 17:25:34 1993 UTC (30 years, 5 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.12:	+78 -31 lines
Log Message:	added intermediate sky and changed +c option to -u
#	User	Rev	Content
1	greg	2.9	/* Copyright (c) 1992 Regents of the University of California */
2	greg	1.1
3			#ifndef lint
4			static char SCCSid[] = "$SunId$ LBL";
5			#endif
6
7			/*
8			* gensky.c - program to generate sky functions.
9			* Our zenith is along the Z-axis, the X-axis
10			* points east, and the Y-axis points north.
11			* Radiance is in watts/steradian/sq. meter.
12			*
13			* 3/26/86
14			*/
15
16			#include <stdio.h>
17
18			#include <math.h>
19
20	greg	1.6	#include "color.h"
21	greg	1.1
22			extern char strcpy(), strcat(), *malloc();
23			extern double stadj(), sdec(), sazi(), salt();
24
25			#define PI 3.141592654
26
27			#define DOT(v1,v2) (v1[0]v2[0]+v1[1]v2[1]+v1[2]*v2[2])
28
29	greg	2.13	#define S_CLEAR 1
30			#define S_OVER 2
31			#define S_UNIF 3
32			#define S_INTER 4
33
34			#define overcast (skytype==S_OVER\|skytype==S_UNIF)
35
36	greg	1.1	double normsc();
37			/* sun calculation constants */
38			extern double s_latitude;
39			extern double s_longitude;
40			extern double s_meridian;
41			/* required values */
42	greg	2.3	int month, day; /* date */
43	greg	2.5	double hour; /* time */
44			int tsolar; /* 0=standard, 1=solar */
45	greg	2.3	double altitude, azimuth; /* or solar angles */
46	greg	1.1	/* default values */
47	greg	2.13	int skytype = S_CLEAR; /* sky type */
48	greg	1.1	int dosun = 1;
49	greg	2.12	double zenithbr = 0.0;
50			int u_zenith = 0; /* -1=irradiance, 1=radiance */
51	greg	1.1	double turbidity = 2.75;
52			double gprefl = 0.2;
53			/* computed values */
54			double sundir[3];
55			double groundbr;
56			double F2;
57	greg	2.12	double solarbr = 0.0;
58			int u_solar = 0; /* -1=irradiance, 1=radiance */
59	greg	1.1
60			char *progname;
61			char errmsg[128];
62
63
64			main(argc, argv)
65			int argc;
66			char *argv[];
67			{
68			int i;
69
70			progname = argv[0];
71			if (argc == 2 && !strcmp(argv[1], "-defaults")) {
72			printdefaults();
73			exit(0);
74			}
75			if (argc < 4)
76			userror("arg count");
77	greg	2.3	if (!strcmp(argv[1], "-ang")) {
78			altitude = atof(argv[2]) * (PI/180);
79			azimuth = atof(argv[3]) * (PI/180);
80			month = 0;
81			} else {
82			month = atoi(argv[1]);
83	greg	2.6	if (month < 1 \|\| month > 12)
84			userror("bad month");
85	greg	2.3	day = atoi(argv[2]);
86	greg	2.6	if (day < 1 \|\| day > 31)
87			userror("bad day");
88	greg	2.3	hour = atof(argv[3]);
89	greg	2.6	if (hour < 0 \|\| hour >= 24)
90			userror("bad hour");
91	greg	2.5	tsolar = argv[3][0] == '+';
92	greg	2.3	}
93	greg	1.1	for (i = 4; i < argc; i++)
94			if (argv[i][0] == '-' \|\| argv[i][0] == '+')
95			switch (argv[i][1]) {
96			case 's':
97	greg	2.13	skytype = S_CLEAR;
98	greg	1.1	dosun = argv[i][0] == '+';
99			break;
100	greg	2.8	case 'r':
101	greg	2.12	case 'R':
102			u_solar = argv[i][1]=='R' ? -1 : 1;
103	greg	2.8	solarbr = atof(argv[++i]);
104			break;
105	greg	1.1	case 'c':
106	greg	2.13	skytype = S_OVER;
107	greg	1.1	dosun = 0;
108			break;
109	greg	2.13	case 'u':
110			skytype = S_UNIF;
111			dosun = 0;
112			break;
113			case 'i':
114			skytype = S_INTER;
115			dosun = argv[i][0] == '+';
116			break;
117	greg	1.1	case 't':
118			turbidity = atof(argv[++i]);
119			break;
120			case 'b':
121	greg	2.12	case 'B':
122			u_zenith = argv[i][1]=='B' ? -1 : 1;
123	greg	1.1	zenithbr = atof(argv[++i]);
124			break;
125			case 'g':
126			gprefl = atof(argv[++i]);
127			break;
128			case 'a':
129			s_latitude = atof(argv[++i]) * (PI/180);
130			break;
131			case 'o':
132			s_longitude = atof(argv[++i]) * (PI/180);
133			break;
134			case 'm':
135			s_meridian = atof(argv[++i]) * (PI/180);
136			break;
137			default:
138			sprintf(errmsg, "unknown option: %s", argv[i]);
139			userror(errmsg);
140			}
141			else
142			userror("bad option");
143	greg	1.5
144			if (fabs(s_meridian-s_longitude) > 30*PI/180)
145			fprintf(stderr,
146			"%s: warning: %.1f hours btwn. standard meridian and longitude\n",
147			progname, (s_longitude-s_meridian)*12/PI);
148	greg	1.1
149			printhead(argc, argv);
150
151			computesky();
152			printsky();
153			}
154
155
156			computesky() /* compute sky parameters */
157			{
158	greg	2.12	double normfactor;
159	greg	1.1	/* compute solar direction */
160	greg	2.3	if (month) { /* from date and time */
161			int jd;
162			double sd, st;
163
164			jd = jdate(month, day); /* Julian date */
165			sd = sdec(jd); /* solar declination */
166	greg	2.5	if (tsolar) /* solar time */
167			st = hour;
168			else
169			st = hour + stadj(jd);
170	greg	2.3	altitude = salt(sd, st);
171			azimuth = sazi(sd, st);
172	greg	2.13	printf("# Solar altitude and azimuth: %.1f %.1f\n",
173	greg	2.11	180./PIaltitude, 180./PIazimuth);
174	greg	2.9	}
175	greg	2.13	if (!overcast && altitude > 87.*PI/180.) {
176	greg	2.9	fprintf(stderr,
177			"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n",
178			progname);
179			printf(
180			"# warning - sun too close to zenith, reducing altitude to 87 degrees\n");
181			altitude = 87.*PI/180.;
182	greg	2.3	}
183	greg	1.1	sundir[0] = -sin(azimuth)*cos(altitude);
184			sundir[1] = -cos(azimuth)*cos(altitude);
185			sundir[2] = sin(altitude);
186
187	greg	2.12	/* Compute normalization factor */
188	greg	2.13	switch (skytype) {
189			case S_UNIF:
190	greg	2.12	normfactor = 1.0;
191	greg	2.13	break;
192			case S_OVER:
193	greg	2.12	normfactor = 0.777778;
194	greg	2.13	break;
195			case S_CLEAR:
196	greg	2.12	F2 = 0.274(0.91 + 10.0exp(-3.0*(PI/2.0-altitude)) +
197			0.45sundir[2]sundir[2]);
198	greg	2.13	normfactor = normsc()/F2/PI;
199			break;
200			case S_INTER:
201			F2 = (2.739 + .9891sin(.3119+2.6altitude)) *
202			exp(-(PI/2.0-altitude)(.4441+1.48altitude));
203			normfactor = normsc()/F2/PI;
204			break;
205	greg	2.12	}
206	greg	1.1	/* Compute zenith brightness */
207	greg	2.12	if (u_zenith == -1)
208			zenithbr /= normfactor*PI;
209			else if (u_zenith == 0) {
210	greg	2.13	if (overcast)
211	greg	1.1	zenithbr = 8.6*sundir[2] + .123;
212	greg	2.12	else
213	greg	1.1	zenithbr = (1.376turbidity-1.81)tan(altitude)+0.38;
214	greg	2.13	if (skytype == S_INTER)
215			zenithbr = (zenithbr + 8.6*sundir[2] + .123)/2.0;
216	greg	2.12	if (zenithbr < 0.0)
217			zenithbr = 0.0;
218			else
219	greg	1.6	zenithbr *= 1000.0/SKYEFFICACY;
220	greg	2.12	}
221	greg	1.1	/* Compute horizontal radiance */
222	greg	2.12	groundbr = zenithbr*normfactor;
223	greg	2.13	printf("# Ground ambient level: %.1f\n", groundbr);
224	greg	2.12	if (sundir[2] > 0.0 && (!u_solar \|\| solarbr > 0.0)) {
225			if (u_solar == -1)
226			solarbr /= 6e-5*sundir[2];
227	greg	2.13	else if (u_solar == 0) {
228	greg	2.12	solarbr = 1.5e9/SUNEFFICACY *
229			(1.147 - .147/(sundir[2]>.16?sundir[2]:.16));
230	greg	2.13	if (skytype == S_INTER)
231			solarbr = 0.15; / fudge factor! */
232			}
233	greg	2.12	groundbr += 6e-5/PIsolarbrsundir[2];
234			} else
235			dosun = 0;
236	greg	1.1	groundbr *= gprefl;
237			}
238
239
240			printsky() /* print out sky */
241			{
242			if (dosun) {
243			printf("\nvoid light solar\n");
244			printf("0\n0\n");
245	greg	1.6	printf("3 %.2e %.2e %.2e\n", solarbr, solarbr, solarbr);
246	greg	1.1	printf("\nsolar source sun\n");
247			printf("0\n0\n");
248			printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]);
249			}
250
251			printf("\nvoid brightfunc skyfunc\n");
252	greg	2.13	printf("2 skybr skybright.cal\n");
253	greg	1.1	printf("0\n");
254	greg	2.13	if (overcast)
255			printf("3 %d %.2e %.2e\n", skytype, zenithbr, groundbr);
256	greg	1.1	else
257	greg	2.13	printf("7 %d %.2e %.2e %.2e %f %f %f\n",
258			skytype, zenithbr, groundbr, F2,
259			sundir[0], sundir[1], sundir[2]);
260	greg	1.1	}
261
262
263			printdefaults() /* print default values */
264			{
265	greg	2.13	switch (skytype) {
266			case S_OVER:
267	greg	1.1	printf("-c\t\t\t\t# Cloudy sky\n");
268	greg	2.13	break;
269			case S_UNIF:
270			printf("-u\t\t\t\t# Uniform cloudy sky\n");
271			break;
272			case S_INTER:
273			if (dosun)
274			printf("+i\t\t\t\t# Intermediate sky with sun\n");
275			else
276			printf("-i\t\t\t\t# Intermediate sky without sun\n");
277			break;
278			case S_CLEAR:
279			if (dosun)
280			printf("+s\t\t\t\t# Sunny sky with sun\n");
281			else
282			printf("-s\t\t\t\t# Sunny sky without sun\n");
283			break;
284			}
285	greg	1.1	printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl);
286			if (zenithbr > 0.0)
287			printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr);
288			else
289			printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity);
290			printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI));
291			printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI));
292			printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI));
293			}
294
295
296			userror(msg) /* print usage error and quit */
297			char *msg;
298			{
299			if (msg != NULL)
300			fprintf(stderr, "%s: Use error - %s\n", progname, msg);
301			fprintf(stderr, "Usage: %s month day hour [options]\n", progname);
302	greg	2.3	fprintf(stderr, " Or: %s -ang altitude azimuth [options]\n", progname);
303	greg	1.1	fprintf(stderr, " Or: %s -defaults\n", progname);
304			exit(1);
305			}
306
307
308			double
309	greg	2.13	normsc() /* compute normalization factor (E0F2/L0) /
310	greg	1.1	{
311	greg	2.13	static double nfc[2][5] = {
312			/* clear sky approx. */
313			{2.766521, 0.547665, -0.369832, 0.009237, 0.059229},
314			/* intermediate sky approx. */
315			{3.5556, -2.7152, -1.3081, 1.0660, 0.60227},
316			};
317			register double *nf;
318	greg	1.1	double x, nsc;
319			register int i;
320			/* polynomial approximation */
321	greg	2.13	nf = nfc[skytype==S_INTER];
322			x = (altitude - PI/4.0)/(PI/4.0);
323			nsc = nf[i=4];
324			while (i--)
325	greg	1.1	nsc = nsc*x + nf[i];
326
327			return(nsc);
328			}
329
330
331			printhead(ac, av) /* print command header */
332			register int ac;
333			register char **av;
334			{
335			putchar('#');
336			while (ac--) {
337			putchar(' ');
338			fputs(*av++, stdout);
339			}
340			putchar('\n');
341			}