src/gen/gensky.c

/* Copyright (c) 1986 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"

#ifndef atof
extern double  atof();
#endif
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])

double  normsc();
                                        /* sun calculation constants */
extern double  s_latitude;
extern double  s_longitude;
extern double  s_meridian;
                                        /* required values */
int  month, day;
double  hour;
                                        /* default values */
int  cloudy = 0;
int  dosun = 1;
double  zenithbr = -1.0;
double  turbidity = 2.75;
double  gprefl = 0.2;
                                        /* computed values */
double  sundir[3];
double  groundbr;
double  F2;
double  solarbr;

char  *progname;
char  errmsg[128];


main(argc, argv)
int  argc;
char  *argv[];
{
        extern double  fabs();
        int  i;

        progname = argv[0];
        if (argc == 2 && !strcmp(argv[1], "-defaults")) {
                printdefaults();
                exit(0);
        }
        if (argc < 4)
                userror("arg count");
        month = atoi(argv[1]);
        day = atoi(argv[2]);
        hour = atof(argv[3]);
        for (i = 4; i < argc; i++)
                if (argv[i][0] == '-' || argv[i][0] == '+')
                        switch (argv[i][1]) {
                        case 's':
                                cloudy = 0;
                                dosun = argv[i][0] == '+';
                                break;
                        case 'c':
                                cloudy = 1;
                                dosun = 0;
                                break;
                        case 't':
                                turbidity = atof(argv[++i]);
                                break;
                        case 'b':
                                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 */
{
        int  jd;
        double  sd, st;
        double  altitude, azimuth;
                                        /* compute solar direction */
        jd = jdate(month, day);                 /* Julian date */
        sd = sdec(jd);                          /* solar declination */
        st = hour + stadj(jd);                  /* solar time */
        altitude = salt(sd, st);
        azimuth = sazi(sd, st);
        sundir[0] = -sin(azimuth)*cos(altitude);
        sundir[1] = -cos(azimuth)*cos(altitude);
        sundir[2] = sin(altitude);

                                        /* Compute zenith brightness */
        if (zenithbr <= 0.0)
                if (cloudy) {
                        zenithbr = 8.6*sundir[2] + .123;
                        zenithbr *= 1000.0/SKYEFFICACY;
                } else {
                        zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
                        zenithbr *= 1000.0/SKYEFFICACY;
                }
        if (zenithbr < 0.0)
                zenithbr = 0.0;
                                        /* Compute horizontal radiance */
        if (cloudy) {
                groundbr = zenithbr*0.777778;
                printf("# Ground ambient level: %f\n", groundbr);
        } else {
                F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) +
                                0.45*sundir[2]*sundir[2]);
                groundbr = zenithbr*normsc(PI/2.0-altitude)/F2/PI;
                printf("# Ground ambient level: %f\n", groundbr);
                if (sundir[2] > 0.0) {
                        if (sundir[2] > .16)
                                solarbr = (1.5e9/SUNEFFICACY) *
                                        (1.147 - .147/sundir[2]);
                        else
                                solarbr = 1.5e9/SUNEFFICACY*(1.147-.147/.16);
                        groundbr += solarbr*6e-5*sundir[2]/PI;
                } 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 skybright skybright.cal\n");
        printf("0\n");
        if (cloudy)
                printf("3 1 %.2e %.2e\n", zenithbr, groundbr);
        else
                printf("7 -1 %.2e %.2e %.2e %f %f %f\n", zenithbr, groundbr,
                                F2, sundir[0], sundir[1], sundir[2]);
}


printdefaults()                 /* print default values */
{
        if (cloudy)
                printf("-c\t\t\t\t# Cloudy sky\n");
        else 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");
        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 -defaults\n", progname);
        exit(1);
}


double
normsc(theta)                   /* compute normalization factor (E0*F2/L0) */
double  theta;
{
        static double  nf[5] = {2.766521, 0.547665,
                                -0.369832, 0.009237, 0.059229};
        double  x, nsc;
        register int  i;
                                        /* polynomial approximation */
        x = (theta - PI/4.0)/(PI/4.0);
        nsc = nf[4];
        for (i = 3; i >= 0; 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:	2.2
Committed:	Thu Dec 19 15:09:28 1991 UTC (32 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.1:	+4 -1 lines
Log Message:	removed atof declaration for NeXT
#	User	Rev	Content
1	greg	1.1	/* Copyright (c) 1986 Regents of the University of California */
2
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	greg	2.2	#ifndef atof
23			extern double atof();
24			#endif
25	greg	1.1	extern char strcpy(), strcat(), *malloc();
26			extern double stadj(), sdec(), sazi(), salt();
27
28			#define PI 3.141592654
29
30			#define DOT(v1,v2) (v1[0]v2[0]+v1[1]v2[1]+v1[2]*v2[2])
31
32			double normsc();
33			/* sun calculation constants */
34			extern double s_latitude;
35			extern double s_longitude;
36			extern double s_meridian;
37			/* required values */
38			int month, day;
39			double hour;
40			/* default values */
41			int cloudy = 0;
42			int dosun = 1;
43			double zenithbr = -1.0;
44			double turbidity = 2.75;
45			double gprefl = 0.2;
46			/* computed values */
47			double sundir[3];
48			double groundbr;
49			double F2;
50			double solarbr;
51
52			char *progname;
53			char errmsg[128];
54
55
56			main(argc, argv)
57			int argc;
58			char *argv[];
59			{
60	greg	2.2	extern double fabs();
61	greg	1.1	int i;
62
63			progname = argv[0];
64			if (argc == 2 && !strcmp(argv[1], "-defaults")) {
65			printdefaults();
66			exit(0);
67			}
68			if (argc < 4)
69			userror("arg count");
70			month = atoi(argv[1]);
71			day = atoi(argv[2]);
72			hour = atof(argv[3]);
73			for (i = 4; i < argc; i++)
74			if (argv[i][0] == '-' \|\| argv[i][0] == '+')
75			switch (argv[i][1]) {
76			case 's':
77			cloudy = 0;
78			dosun = argv[i][0] == '+';
79			break;
80			case 'c':
81			cloudy = 1;
82			dosun = 0;
83			break;
84			case 't':
85			turbidity = atof(argv[++i]);
86			break;
87			case 'b':
88			zenithbr = atof(argv[++i]);
89			break;
90			case 'g':
91			gprefl = atof(argv[++i]);
92			break;
93			case 'a':
94			s_latitude = atof(argv[++i]) * (PI/180);
95			break;
96			case 'o':
97			s_longitude = atof(argv[++i]) * (PI/180);
98			break;
99			case 'm':
100			s_meridian = atof(argv[++i]) * (PI/180);
101			break;
102			default:
103			sprintf(errmsg, "unknown option: %s", argv[i]);
104			userror(errmsg);
105			}
106			else
107			userror("bad option");
108	greg	1.5
109			if (fabs(s_meridian-s_longitude) > 30*PI/180)
110			fprintf(stderr,
111			"%s: warning: %.1f hours btwn. standard meridian and longitude\n",
112			progname, (s_longitude-s_meridian)*12/PI);
113	greg	1.1
114			printhead(argc, argv);
115
116			computesky();
117			printsky();
118			}
119
120
121			computesky() /* compute sky parameters */
122			{
123			int jd;
124			double sd, st;
125			double altitude, azimuth;
126			/* compute solar direction */
127			jd = jdate(month, day); /* Julian date */
128			sd = sdec(jd); /* solar declination */
129			st = hour + stadj(jd); /* solar time */
130			altitude = salt(sd, st);
131			azimuth = sazi(sd, st);
132			sundir[0] = -sin(azimuth)*cos(altitude);
133			sundir[1] = -cos(azimuth)*cos(altitude);
134			sundir[2] = sin(altitude);
135
136			/* Compute zenith brightness */
137			if (zenithbr <= 0.0)
138			if (cloudy) {
139			zenithbr = 8.6*sundir[2] + .123;
140	greg	1.6	zenithbr *= 1000.0/SKYEFFICACY;
141	greg	1.1	} else {
142			zenithbr = (1.376turbidity-1.81)tan(altitude)+0.38;
143	greg	1.6	zenithbr *= 1000.0/SKYEFFICACY;
144	greg	1.1	}
145	greg	1.2	if (zenithbr < 0.0)
146			zenithbr = 0.0;
147	greg	1.1	/* Compute horizontal radiance */
148			if (cloudy) {
149			groundbr = zenithbr*0.777778;
150			printf("# Ground ambient level: %f\n", groundbr);
151			} else {
152			F2 = 0.274(0.91 + 10.0exp(-3.0*(PI/2.0-altitude)) +
153			0.45sundir[2]sundir[2]);
154			groundbr = zenithbr*normsc(PI/2.0-altitude)/F2/PI;
155			printf("# Ground ambient level: %f\n", groundbr);
156			if (sundir[2] > 0.0) {
157			if (sundir[2] > .16)
158	greg	1.6	solarbr = (1.5e9/SUNEFFICACY) *
159			(1.147 - .147/sundir[2]);
160	greg	1.1	else
161	greg	1.6	solarbr = 1.5e9/SUNEFFICACY*(1.147-.147/.16);
162	greg	1.1	groundbr += solarbr6e-5sundir[2]/PI;
163			} else
164			dosun = 0;
165			}
166			groundbr *= gprefl;
167			}
168
169
170			printsky() /* print out sky */
171			{
172			if (dosun) {
173			printf("\nvoid light solar\n");
174			printf("0\n0\n");
175	greg	1.6	printf("3 %.2e %.2e %.2e\n", solarbr, solarbr, solarbr);
176	greg	1.1	printf("\nsolar source sun\n");
177			printf("0\n0\n");
178			printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]);
179			}
180
181			printf("\nvoid brightfunc skyfunc\n");
182			printf("2 skybright skybright.cal\n");
183			printf("0\n");
184			if (cloudy)
185	greg	1.6	printf("3 1 %.2e %.2e\n", zenithbr, groundbr);
186	greg	1.1	else
187	greg	1.6	printf("7 -1 %.2e %.2e %.2e %f %f %f\n", zenithbr, groundbr,
188			F2, sundir[0], sundir[1], sundir[2]);
189	greg	1.1	}
190
191
192			printdefaults() /* print default values */
193			{
194			if (cloudy)
195			printf("-c\t\t\t\t# Cloudy sky\n");
196			else if (dosun)
197			printf("+s\t\t\t\t# Sunny sky with sun\n");
198			else
199			printf("-s\t\t\t\t# Sunny sky without sun\n");
200			printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl);
201			if (zenithbr > 0.0)
202			printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr);
203			else
204			printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity);
205			printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI));
206			printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI));
207			printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI));
208			}
209
210
211			userror(msg) /* print usage error and quit */
212			char *msg;
213			{
214			if (msg != NULL)
215			fprintf(stderr, "%s: Use error - %s\n", progname, msg);
216			fprintf(stderr, "Usage: %s month day hour [options]\n", progname);
217			fprintf(stderr, " Or: %s -defaults\n", progname);
218			exit(1);
219			}
220
221
222			double
223			normsc(theta) /* compute normalization factor (E0F2/L0) /
224			double theta;
225			{
226			static double nf[5] = {2.766521, 0.547665,
227			-0.369832, 0.009237, 0.059229};
228			double x, nsc;
229			register int i;
230			/* polynomial approximation */
231			x = (theta - PI/4.0)/(PI/4.0);
232			nsc = nf[4];
233			for (i = 3; i >= 0; i--)
234			nsc = nsc*x + nf[i];
235
236			return(nsc);
237			}
238
239
240			printhead(ac, av) /* print command header */
241			register int ac;
242			register char **av;
243			{
244			putchar('#');
245			while (ac--) {
246			putchar(' ');
247			fputs(*av++, stdout);
248			}
249			putchar('\n');
250			}