1 |
greg |
2.9 |
/* Copyright (c) 1992 Regents of the University of California */ |
2 |
greg |
1.1 |
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#ifndef lint |
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static char SCCSid[] = "$SunId$ LBL"; |
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#endif |
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/* |
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* gensky.c - program to generate sky functions. |
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* Our zenith is along the Z-axis, the X-axis |
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* points east, and the Y-axis points north. |
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* Radiance is in watts/steradian/sq. meter. |
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* |
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* 3/26/86 |
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*/ |
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#include <stdio.h> |
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#include <math.h> |
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greg |
1.6 |
#include "color.h" |
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greg |
1.1 |
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extern char *strcpy(), *strcat(), *malloc(); |
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extern double stadj(), sdec(), sazi(), salt(); |
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#define PI 3.141592654 |
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#define DOT(v1,v2) (v1[0]*v2[0]+v1[1]*v2[1]+v1[2]*v2[2]) |
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greg |
2.13 |
#define S_CLEAR 1 |
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#define S_OVER 2 |
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#define S_UNIF 3 |
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#define S_INTER 4 |
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#define overcast (skytype==S_OVER|skytype==S_UNIF) |
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greg |
1.1 |
double normsc(); |
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/* sun calculation constants */ |
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extern double s_latitude; |
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extern double s_longitude; |
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extern double s_meridian; |
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/* required values */ |
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greg |
2.3 |
int month, day; /* date */ |
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greg |
2.5 |
double hour; /* time */ |
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int tsolar; /* 0=standard, 1=solar */ |
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greg |
2.3 |
double altitude, azimuth; /* or solar angles */ |
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greg |
1.1 |
/* default values */ |
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greg |
2.13 |
int skytype = S_CLEAR; /* sky type */ |
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greg |
1.1 |
int dosun = 1; |
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greg |
2.12 |
double zenithbr = 0.0; |
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int u_zenith = 0; /* -1=irradiance, 1=radiance */ |
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greg |
1.1 |
double turbidity = 2.75; |
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double gprefl = 0.2; |
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/* computed values */ |
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double sundir[3]; |
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double groundbr; |
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double F2; |
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greg |
2.12 |
double solarbr = 0.0; |
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int u_solar = 0; /* -1=irradiance, 1=radiance */ |
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greg |
1.1 |
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char *progname; |
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char errmsg[128]; |
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main(argc, argv) |
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int argc; |
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char *argv[]; |
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{ |
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int i; |
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progname = argv[0]; |
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if (argc == 2 && !strcmp(argv[1], "-defaults")) { |
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printdefaults(); |
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exit(0); |
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} |
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if (argc < 4) |
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userror("arg count"); |
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greg |
2.3 |
if (!strcmp(argv[1], "-ang")) { |
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altitude = atof(argv[2]) * (PI/180); |
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azimuth = atof(argv[3]) * (PI/180); |
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month = 0; |
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} else { |
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month = atoi(argv[1]); |
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greg |
2.6 |
if (month < 1 || month > 12) |
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userror("bad month"); |
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greg |
2.3 |
day = atoi(argv[2]); |
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greg |
2.6 |
if (day < 1 || day > 31) |
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userror("bad day"); |
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greg |
2.3 |
hour = atof(argv[3]); |
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greg |
2.6 |
if (hour < 0 || hour >= 24) |
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userror("bad hour"); |
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greg |
2.5 |
tsolar = argv[3][0] == '+'; |
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greg |
2.3 |
} |
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greg |
1.1 |
for (i = 4; i < argc; i++) |
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if (argv[i][0] == '-' || argv[i][0] == '+') |
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switch (argv[i][1]) { |
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case 's': |
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greg |
2.13 |
skytype = S_CLEAR; |
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greg |
1.1 |
dosun = argv[i][0] == '+'; |
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break; |
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greg |
2.8 |
case 'r': |
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greg |
2.12 |
case 'R': |
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u_solar = argv[i][1]=='R' ? -1 : 1; |
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greg |
2.8 |
solarbr = atof(argv[++i]); |
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break; |
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greg |
1.1 |
case 'c': |
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greg |
2.13 |
skytype = S_OVER; |
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greg |
1.1 |
dosun = 0; |
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break; |
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greg |
2.13 |
case 'u': |
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skytype = S_UNIF; |
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dosun = 0; |
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break; |
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case 'i': |
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skytype = S_INTER; |
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dosun = argv[i][0] == '+'; |
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break; |
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greg |
1.1 |
case 't': |
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turbidity = atof(argv[++i]); |
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break; |
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case 'b': |
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greg |
2.12 |
case 'B': |
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u_zenith = argv[i][1]=='B' ? -1 : 1; |
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greg |
1.1 |
zenithbr = atof(argv[++i]); |
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break; |
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case 'g': |
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gprefl = atof(argv[++i]); |
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break; |
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case 'a': |
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s_latitude = atof(argv[++i]) * (PI/180); |
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break; |
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case 'o': |
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s_longitude = atof(argv[++i]) * (PI/180); |
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break; |
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case 'm': |
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s_meridian = atof(argv[++i]) * (PI/180); |
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break; |
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default: |
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sprintf(errmsg, "unknown option: %s", argv[i]); |
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userror(errmsg); |
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} |
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else |
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userror("bad option"); |
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greg |
1.5 |
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if (fabs(s_meridian-s_longitude) > 30*PI/180) |
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fprintf(stderr, |
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"%s: warning: %.1f hours btwn. standard meridian and longitude\n", |
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progname, (s_longitude-s_meridian)*12/PI); |
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greg |
1.1 |
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printhead(argc, argv); |
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computesky(); |
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printsky(); |
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} |
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156 |
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computesky() /* compute sky parameters */ |
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{ |
158 |
greg |
2.12 |
double normfactor; |
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greg |
1.1 |
/* compute solar direction */ |
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greg |
2.3 |
if (month) { /* from date and time */ |
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int jd; |
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double sd, st; |
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jd = jdate(month, day); /* Julian date */ |
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sd = sdec(jd); /* solar declination */ |
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greg |
2.5 |
if (tsolar) /* solar time */ |
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st = hour; |
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else |
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st = hour + stadj(jd); |
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greg |
2.3 |
altitude = salt(sd, st); |
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azimuth = sazi(sd, st); |
172 |
greg |
2.13 |
printf("# Solar altitude and azimuth: %.1f %.1f\n", |
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greg |
2.11 |
180./PI*altitude, 180./PI*azimuth); |
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greg |
2.9 |
} |
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greg |
2.13 |
if (!overcast && altitude > 87.*PI/180.) { |
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greg |
2.9 |
fprintf(stderr, |
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"%s: warning - sun too close to zenith, reducing altitude to 87 degrees\n", |
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progname); |
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printf( |
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"# warning - sun too close to zenith, reducing altitude to 87 degrees\n"); |
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altitude = 87.*PI/180.; |
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greg |
2.3 |
} |
183 |
greg |
1.1 |
sundir[0] = -sin(azimuth)*cos(altitude); |
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sundir[1] = -cos(azimuth)*cos(altitude); |
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sundir[2] = sin(altitude); |
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greg |
2.12 |
/* Compute normalization factor */ |
188 |
greg |
2.13 |
switch (skytype) { |
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case S_UNIF: |
190 |
greg |
2.12 |
normfactor = 1.0; |
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greg |
2.13 |
break; |
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case S_OVER: |
193 |
greg |
2.12 |
normfactor = 0.777778; |
194 |
greg |
2.13 |
break; |
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case S_CLEAR: |
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greg |
2.12 |
F2 = 0.274*(0.91 + 10.0*exp(-3.0*(PI/2.0-altitude)) + |
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0.45*sundir[2]*sundir[2]); |
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greg |
2.13 |
normfactor = normsc()/F2/PI; |
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break; |
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case S_INTER: |
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F2 = (2.739 + .9891*sin(.3119+2.6*altitude)) * |
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exp(-(PI/2.0-altitude)*(.4441+1.48*altitude)); |
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normfactor = normsc()/F2/PI; |
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break; |
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greg |
2.12 |
} |
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greg |
1.1 |
/* Compute zenith brightness */ |
207 |
greg |
2.12 |
if (u_zenith == -1) |
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zenithbr /= normfactor*PI; |
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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 = (1.376*turbidity-1.81)*tan(altitude)+0.38; |
214 |
greg |
2.13 |
if (skytype == S_INTER) |
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zenithbr = (zenithbr + 8.6*sundir[2] + .123)/2.0; |
216 |
greg |
2.12 |
if (zenithbr < 0.0) |
217 |
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zenithbr = 0.0; |
218 |
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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)) { |
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if (u_solar == -1) |
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solarbr /= 6e-5*sundir[2]; |
227 |
greg |
2.13 |
else if (u_solar == 0) { |
228 |
greg |
2.12 |
solarbr = 1.5e9/SUNEFFICACY * |
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(1.147 - .147/(sundir[2]>.16?sundir[2]:.16)); |
230 |
greg |
2.13 |
if (skytype == S_INTER) |
231 |
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solarbr *= 0.15; /* fudge factor! */ |
232 |
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} |
233 |
greg |
2.12 |
groundbr += 6e-5/PI*solarbr*sundir[2]; |
234 |
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} else |
235 |
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dosun = 0; |
236 |
greg |
1.1 |
groundbr *= gprefl; |
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} |
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239 |
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240 |
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printsky() /* print out sky */ |
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{ |
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if (dosun) { |
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printf("\nvoid light solar\n"); |
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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"); |
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printf("0\n0\n"); |
248 |
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printf("4 %f %f %f 0.5\n", sundir[0], sundir[1], sundir[2]); |
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} |
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251 |
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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 |
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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", |
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skytype, zenithbr, groundbr, F2, |
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sundir[0], sundir[1], sundir[2]); |
260 |
greg |
1.1 |
} |
261 |
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262 |
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263 |
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printdefaults() /* print default values */ |
264 |
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{ |
265 |
greg |
2.13 |
switch (skytype) { |
266 |
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case S_OVER: |
267 |
greg |
1.1 |
printf("-c\t\t\t\t# Cloudy sky\n"); |
268 |
greg |
2.13 |
break; |
269 |
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case S_UNIF: |
270 |
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printf("-u\t\t\t\t# Uniform cloudy sky\n"); |
271 |
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break; |
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case S_INTER: |
273 |
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if (dosun) |
274 |
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printf("+i\t\t\t\t# Intermediate sky with sun\n"); |
275 |
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else |
276 |
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printf("-i\t\t\t\t# Intermediate sky without sun\n"); |
277 |
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break; |
278 |
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case S_CLEAR: |
279 |
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if (dosun) |
280 |
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printf("+s\t\t\t\t# Sunny sky with sun\n"); |
281 |
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else |
282 |
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printf("-s\t\t\t\t# Sunny sky without sun\n"); |
283 |
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break; |
284 |
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} |
285 |
greg |
1.1 |
printf("-g %f\t\t\t# Ground plane reflectance\n", gprefl); |
286 |
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if (zenithbr > 0.0) |
287 |
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printf("-b %f\t\t\t# Zenith radiance (watts/ster/m2\n", zenithbr); |
288 |
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else |
289 |
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printf("-t %f\t\t\t# Atmospheric turbidity\n", turbidity); |
290 |
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printf("-a %f\t\t\t# Site latitude (degrees)\n", s_latitude*(180/PI)); |
291 |
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printf("-o %f\t\t\t# Site longitude (degrees)\n", s_longitude*(180/PI)); |
292 |
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printf("-m %f\t\t\t# Standard meridian (degrees)\n", s_meridian*(180/PI)); |
293 |
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} |
294 |
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295 |
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296 |
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userror(msg) /* print usage error and quit */ |
297 |
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char *msg; |
298 |
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{ |
299 |
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if (msg != NULL) |
300 |
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fprintf(stderr, "%s: Use error - %s\n", progname, msg); |
301 |
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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 |
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exit(1); |
305 |
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} |
306 |
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307 |
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308 |
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double |
309 |
greg |
2.13 |
normsc() /* compute normalization factor (E0*F2/L0) */ |
310 |
greg |
1.1 |
{ |
311 |
greg |
2.13 |
static double nfc[2][5] = { |
312 |
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/* clear sky approx. */ |
313 |
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{2.766521, 0.547665, -0.369832, 0.009237, 0.059229}, |
314 |
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/* intermediate sky approx. */ |
315 |
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{3.5556, -2.7152, -1.3081, 1.0660, 0.60227}, |
316 |
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}; |
317 |
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register double *nf; |
318 |
greg |
1.1 |
double x, nsc; |
319 |
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register int i; |
320 |
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/* polynomial approximation */ |
321 |
greg |
2.13 |
nf = nfc[skytype==S_INTER]; |
322 |
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x = (altitude - PI/4.0)/(PI/4.0); |
323 |
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nsc = nf[i=4]; |
324 |
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while (i--) |
325 |
greg |
1.1 |
nsc = nsc*x + nf[i]; |
326 |
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327 |
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return(nsc); |
328 |
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} |
329 |
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330 |
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331 |
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printhead(ac, av) /* print command header */ |
332 |
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register int ac; |
333 |
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register char **av; |
334 |
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{ |
335 |
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putchar('#'); |
336 |
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while (ac--) { |
337 |
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putchar(' '); |
338 |
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fputs(*av++, stdout); |
339 |
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} |
340 |
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putchar('\n'); |
341 |
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} |