src/gen/genssky.c

#ifndef lint
static const char RCSid[] = "$Id: genssky.c,v 2.3 2024/08/02 18:47:25 greg Exp $";
#endif
/* Main function for generating spectral sky */
/* Cloudy sky computed as weight average of clear and cie overcast sky */

#include "atmos.h"
#include "copyright.h"
#include "resolu.h"
#include "rtio.h"
#include <ctype.h>
#ifdef _WIN32
#include <windows.h>
#else
#include <errno.h>
#include <sys/stat.h>
#include <sys/types.h>
#endif

char *progname;

const double ARCTIC_LAT = 67.;
const double TROPIC_LAT = 23.;
const int SUMMER_START = 4;
const int SUMMER_END = 9;
const double GNORM = 0.777778;

const double D65EFF = 203.; /* standard illuminant D65 */

/* Mean normalized relative daylight spectra where CCT = 6415K for overcast; */
const double D6415[NSSAMP] = {0.63231, 1.06171, 1.00779, 1.36423, 1.34133,
                              1.27258, 1.26276, 1.26352, 1.22201, 1.13246,
                              1.0434,  1.05547, 0.98212, 0.94445, 0.9722,
                              0.82387, 0.87853, 0.82559, 0.75111, 0.78925};

/* 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}};

static int make_directory(const char *path) {
#ifdef _WIN32
  if (CreateDirectory(path, NULL) || GetLastError() == ERROR_ALREADY_EXISTS) {
    return 1;
  }
  return 0;
#else
  if (mkdir(path, 0777) == 0 || errno == EEXIST) {
    return 1;
  }
  return 0;
#endif
}

inline static float deg2rad(float deg) { return deg * (PI / 180.); }

static int cvthour(char *hs, int *tsolar, double *hour) {
  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);
}

static void basename(const char *path, char *output, size_t outsize) {
  const char *last_slash = strrchr(path, '/');
  const char *last_backslash = strrchr(path, '\\');
  const char *filename = path;
  const char *last_dot;

  if (last_slash && last_backslash) {
    filename =
        (last_slash > last_backslash) ? last_slash + 1 : last_backslash + 1;
  } else if (last_slash) {
    filename = last_slash + 1;
  } else if (last_backslash) {
    filename = last_backslash + 1;
  }

  last_dot = strrchr(filename, '.');
  if (last_dot) {
    size_t length = last_dot - filename;
    if (length < outsize) {
      strncpy(output, filename, length);
      output[length] = '\0';
    } else {
      strncpy(output, filename, outsize - 1);
      output[outsize - 1] = '\0';
    }
  }
}

static char *join_paths(const char *path1, const char *path2) {
  size_t len1 = strlen(path1);
  size_t len2 = strlen(path2);
  int need_separator = (path1[len1 - 1] != DIRSEP);

  char *result = malloc(len1 + len2 + (need_separator ? 2 : 1));
  if (!result)
    return NULL;

  strcpy(result, path1);
  if (need_separator) {
    result[len1] = DIRSEP;
    len1++;
  }
  strcpy(result + len1, path2);

  return result;
}

static inline double wmean2(const double a, const double b, const double x) {
  return a * (1 - x) + b * x;
}

static inline double wmean(const double a, const double x, const double b,
                           const double y) {
  return (a * x + b * y) / (a + b);
}

static double get_zenith_brightness(const double sundir[3]) {
  double zenithbr;
  if (sundir[2] < 0) {
    zenithbr = 0;
  } else {
    zenithbr = (8.6 * sundir[2] + .123) * 1000.0 / D65EFF;
  }
  return zenithbr;
}

/* from gensky.c */
static double get_overcast_brightness(const double dz, const double zenithbr) {
  double groundbr = zenithbr * GNORM;
  return wmean(pow(dz + 1.01, 10), zenithbr * (1 + 2 * dz) / 3,
               pow(dz + 1.01, -10), groundbr);
}

static void write_header(const int argc, char **argv, const double cloud_cover,
                         const double grefl, const int res) {
  int i;
  printf("# ");
  for (i = 0; i < argc; i++) {
    printf("%s ", argv[i]);
  }
  printf("\n");
  printf(
      "#Cloud cover: %g\n#Ground reflectance: %g\n#Sky map resolution: %d\n\n",
      cloud_cover, grefl, res);
}

static void write_rad(const double *sun_radiance, const FVECT sundir,
                      const char *ddir, const char *skyfile) {
  if (sundir[2] > 0) {
    printf("void spectrum sunrad\n0\n0\n22 380 780 ");
    /* Normalize to one */
    double sum = 0.0;
    int i;
    for (i = 0; i < NSSAMP; ++i) {
      sum += sun_radiance[i];
    }
    double mean = sum / NSSAMP;
    for (i = 0; i < NSSAMP; ++i) {
      printf("%.3f ", sun_radiance[i] / mean);
    }
    double intensity = mean * WVLSPAN;
    printf("\n\nsunrad light solar\n0\n0\n3 %.1f %.1f %.1f\n\n", intensity,
           intensity, intensity);
    printf("solar source sun\n0\n0\n4 %f %f %f 0.533\n\n", sundir[0], sundir[1],
           sundir[2]);
  }
  printf("void specpict skyfunc\n5 noop %s . 'atan2(Dy,Dx)/PI+1' "
         "'acos(Dz)/PI'\n0\n0\n\n",
         skyfile);
}

static void write_hsr_header(FILE *fp, RESOLU *res) {
  float wvsplit[4] = {380, 480, 588, 780};
  newheader("RADIANCE", fp);
  fputncomp(NSSAMP, fp);
  fputwlsplit(wvsplit, fp);
  fputformat(SPECFMT, fp);
  fputc('\n', fp);
  fputsresolu(res, fp);
}

static inline float frac(float x) { return x - floor(x); }

int gen_spect_sky(DATARRAY *tau_clear, DATARRAY *scat_clear,
                  DATARRAY *scat1m_clear, DATARRAY *irrad_clear,
                  const double cloud_cover, const FVECT sundir,
                  const double grefl, const int res, const char *outname,
                  const char *ddir) {
  char skyfile[PATH_MAX];
  char grndfile[PATH_MAX];
  if (!snprintf(skyfile, sizeof(skyfile), "%s%c%s_sky.hsr", ddir, DIRSEP,
                outname)) {
    fprintf(stderr, "Error setting sky file name\n");
    return 0;
  };
  int xres = res;
  int yres = xres / 2;
  RESOLU rs = {PIXSTANDARD, xres, yres};
  FILE *skyfp = fopen(skyfile, "w");
  write_hsr_header(skyfp, &rs);

  CNDX[3] = NSSAMP;

  FVECT view_point = {0, 0, ER + 10};
  const double radius = VLEN(view_point);
  const double sun_ct = fdot(view_point, sundir) / radius;
  int i, j, k;
  for (j = 0; j < yres; ++j) {
    for (i = 0; i < xres; ++i) {
      SCOLOR radiance = {0};
      SCOLR sky_sclr = {0};

      float px = i / (xres - 1.0);
      float py = j / (yres - 1.0);
      float lambda = ((1 - py) * PI) - (PI / 2.0);
      float phi = (px * 2.0 * PI) - PI;

      FVECT rdir = {cos(lambda) * cos(phi), cos(lambda) * sin(phi),
                    sin(lambda)};

      const double mu = fdot(view_point, rdir) / radius;
      const double nu = fdot(rdir, sundir);

      /* hit ground */
      if (rdir[2] < 0) {
        get_ground_radiance(tau_clear, scat_clear, scat1m_clear, irrad_clear,
                            view_point, rdir, radius, mu, sun_ct, nu, grefl,
                            sundir, radiance);
      } else {
        get_sky_radiance(scat_clear, scat1m_clear, radius, mu, sun_ct, nu,
                         radiance);
      }

      for (k = 0; k < NSSAMP; ++k) {
        radiance[k] *= WVLSPAN;
      }

      if (cloud_cover > 0) {
        double zenithbr = get_zenith_brightness(sundir);
        double grndbr = zenithbr * GNORM;
        double skybr = get_overcast_brightness(rdir[2], zenithbr);
        if (rdir[2] < 0) {
          for (k = 0; k < NSSAMP; ++k) {
            radiance[k] = wmean2(radiance[k], grndbr * D6415[k], cloud_cover);
          }
        } else {
          for (k = 0; k < NSSAMP; ++k) {
            radiance[k] = wmean2(radiance[k], skybr * D6415[k], cloud_cover);
          }
        }
      }

      scolor2scolr(sky_sclr, radiance, 20);
      putbinary(sky_sclr, LSCOLR, 1, skyfp);
    }
  }
  fclose(skyfp);

  /* Get solar radiance */
  double sun_radiance[NSSAMP] = {0};
  get_solar_radiance(tau_clear, scat_clear, scat1m_clear, sundir, radius,
                     sun_ct, sun_radiance);
  if (cloud_cover > 0) {
    double zenithbr = get_zenith_brightness(sundir);
    double skybr = get_overcast_brightness(sundir[2], zenithbr);
    int i;
    for (i = 0; i < NSSAMP; ++i) {
      sun_radiance[i] =
          wmean2(sun_radiance[i], D6415[i] * skybr / WVLSPAN, cloud_cover);
    }
  }

  write_rad(sun_radiance, sundir, ddir, skyfile);
  return 1;
}

static DpPaths get_dppaths(const char *dir, const double aod, const char *mname,
                           const char *tag) {
  DpPaths paths;

  snprintf(paths.tau, PATH_MAX, "%s%ctau_%s_%s_%.2f.dat", dir, DIRSEP, tag,
           mname, aod);
  snprintf(paths.scat, PATH_MAX, "%s%cscat_%s_%s_%.2f.dat", dir, DIRSEP, tag,
           mname, aod);
  snprintf(paths.scat1m, PATH_MAX, "%s%cscat1m_%s_%s_%.2f.dat", dir, DIRSEP,
           tag, mname, aod);
  snprintf(paths.irrad, PATH_MAX, "%s%cirrad_%s_%s_%.2f.dat", dir, DIRSEP, tag,
           mname, aod);

  return paths;
}

static void set_rayleigh_density_profile(Atmosphere *atmos, char *tag,
                                         const int is_summer,
                                         const double s_latitude) {
  if (fabs(s_latitude * 180.0 / PI) > ARCTIC_LAT) {
    tag[0] = 's';
    if (is_summer) {
      tag[1] = 's';
      atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_SS;
      atmos->beta_r0 = BR0_SS;
    } else {
      tag[1] = 'w';
      atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_SW;
      atmos->beta_r0 = BR0_SW;
    }
  } else if (fabs(s_latitude * 180.0 / PI) > TROPIC_LAT) {
    tag[0] = 'm';
    if (is_summer) {
      tag[1] = 's';
      atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_MS;
      atmos->beta_r0 = BR0_MS;
    } else {
      tag[1] = 'w';
      atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_MW;
      atmos->beta_r0 = BR0_MW;
    }
  } else {
    tag[0] = 't';
    tag[1] = 'r';
    atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_T;
    atmos->beta_r0 = BR0_T;
  }
  tag[2] = '\0';
}

static Atmosphere init_atmos(const double aod, const double grefl) {
  Atmosphere atmos = {.ozone_density = {.layers =
                                            {
                                                {.width = 25000.0,
                                                 .exp_term = 0.0,
                                                 .exp_scale = 0.0,
                                                 .linear_term = 1.0 / 15000.0,
                                                 .constant_term = -2.0 / 3.0},
                                                {.width = AH,
                                                 .exp_term = 0.0,
                                                 .exp_scale = 0.0,
                                                 .linear_term = -1.0 / 15000.0,
                                                 .constant_term = 8.0 / 3.0},
                                            }},
                      .rayleigh_density = {.layers =
                                               {
                                                   {.width = AH,
                                                    .exp_term = 1.0,
                                                    .exp_scale = -1.0 / HR_MS,
                                                    .linear_term = 0.0,
                                                    .constant_term = 0.0},
                                               }},
                      .beta_r0 = BR0_MS,
                      .beta_scale = aod / AOD0_CA,
                      .beta_m = NULL,
                      .grefl = grefl};
  return atmos;
}

int main(int argc, char *argv[]) {
  progname = argv[0];
  int month, day;
  double hour;
  FVECT sundir;
  int num_threads = 1;
  int sorder = 4;
  int year = 0;
  int tsolar = 0;
  int got_meridian = 0;
  double grefl = 0.2;
  double ccover = 0.0;
  int res = 64;
  double aod = AOD0_CA;
  char *outname = "out";
  char *mie_path = getpath("mie_ca.dat", getrlibpath(), R_OK);
  char mie_name[20] = "mie_ca";
  char lstag[3];
  char *ddir = ".";
  int i;

  if (argc == 2 && !strcmp(argv[1], "-defaults")) {
    printf("-i %d\t\t\t\t#scattering order\n", sorder);
    printf("-g %f\t\t\t#ground reflectance\n", grefl);
    printf("-c %f\t\t\t#cloud cover\n", ccover);
    printf("-r %d\t\t\t\t#image resolution\n", res);
    printf("-d %f\t\t\t#broadband aerosol optical depth\n", AOD0_CA);
    printf("-f %s\t\t\t\t#output name (-f)\n", outname);
    printf("-p %s\t\t\t\t#atmos data directory\n", ddir);
    exit(0);
  }

  if (argc < 4) {
    fprintf(stderr,
            "Usage: %s month day hour -y year -a lat -o lon -m tz -d aod -r "
            "res -n nproc -c ccover -l mie -g grefl -f outpath\n",
            argv[0]);
    return 0;
  }

  month = atoi(argv[1]);
  if (month < 1 || month > 12) {
    fprintf(stderr, "bad month");
    exit(1);
  }
  day = atoi(argv[2]);
  if (day < 1 || day > 31) {
    fprintf(stderr, "bad month");
    exit(1);
  }
  got_meridian = cvthour(argv[3], &tsolar, &hour);

  if (!compute_sundir(year, month, day, hour, tsolar, sundir)) {
    fprintf(stderr, "Cannot compute solar angle\n");
    exit(1);
  }

  for (i = 4; i < argc; i++) {
    if (argv[i][0] == '-') {
      switch (argv[i][1]) {
      case 'a':
        s_latitude = atof(argv[++i]) * (PI / 180.0);
        break;
      case 'c':
        ccover = atof(argv[++i]);
        break;
      case 'd':
        aod = atof(argv[++i]);
        break;
      case 'f':
        outname = argv[++i];
        break;
      case 'g':
        grefl = atof(argv[++i]);
        break;
      case 'i':
        sorder = atoi(argv[++i]);
        break;
      case 'l':
        mie_path = argv[++i];
        basename(mie_path, mie_name, sizeof(mie_name));
        break;
      case 'm':
        if (got_meridian) {
          ++i;
          break;
        }
        s_meridian = atof(argv[++i]) * (PI / 180.0);
        break;
      case 'n':
        num_threads = atoi(argv[++i]);
        break;
      case 'o':
        s_longitude = atof(argv[++i]) * (PI / 180.0);
        break;
      case 'p':
        ddir = argv[++i];
        break;
      case 'r':
        res = atoi(argv[++i]);
        break;
      case 'y':
        year = atoi(argv[++i]);
        break;
      default:
        fprintf(stderr, "Unknown option %s\n", argv[i]);
        exit(1);
      }
    }
  }
  if (year && (year < 1950) | (year > 2050))
    fprintf(stderr, "%s: warning - year should be in range 1950-2050\n",
            progname);
  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);

  Atmosphere clear_atmos = init_atmos(aod, grefl);

  int is_summer = (month >= SUMMER_START && month <= SUMMER_END);
  if (s_latitude < 0) {
    is_summer = !is_summer;
  }
  set_rayleigh_density_profile(&clear_atmos, lstag, is_summer, s_latitude);

  /* Load mie density data */
  DATARRAY *mie_dp = getdata(mie_path);
  if (mie_dp == NULL) {
    fprintf(stderr, "Error reading mie data\n");
    return 0;
  }
  clear_atmos.beta_m = mie_dp;

  char gsdir[PATH_MAX];
  size_t siz = strlen(ddir);
  if (ISDIRSEP(ddir[siz - 1]))
    ddir[siz - 1] = '\0';
  snprintf(gsdir, PATH_MAX, "%s%catmos_data", ddir, DIRSEP);
  if (!make_directory(gsdir)) {
    fprintf(stderr, "Failed creating atmos_data directory");
    exit(1);
  }
  DpPaths clear_paths = get_dppaths(gsdir, aod, mie_name, lstag);

  if (getpath(clear_paths.tau, ".", R_OK) == NULL ||
      getpath(clear_paths.scat, ".", R_OK) == NULL ||
      getpath(clear_paths.scat1m, ".", R_OK) == NULL ||
      getpath(clear_paths.irrad, ".", R_OK) == NULL) {
    printf("# Pre-computing...\n");
    if (!precompute(sorder, clear_paths, &clear_atmos, num_threads)) {
      fprintf(stderr, "Pre-compute failed\n");
      return 0;
    }
  }

  DATARRAY *tau_clear_dp = getdata(clear_paths.tau);
  DATARRAY *irrad_clear_dp = getdata(clear_paths.irrad);
  DATARRAY *scat_clear_dp = getdata(clear_paths.scat);
  DATARRAY *scat1m_clear_dp = getdata(clear_paths.scat1m);

  write_header(argc, argv, ccover, grefl, res);

  if (!gen_spect_sky(tau_clear_dp, scat_clear_dp, scat1m_clear_dp,
                     irrad_clear_dp, ccover, sundir, grefl, res, outname,
                     ddir)) {
    fprintf(stderr, "gen_spect_sky failed\n");
    exit(1);
  }

  freedata(mie_dp);
  freedata(tau_clear_dp);
  freedata(scat_clear_dp);
  freedata(irrad_clear_dp);
  freedata(scat1m_clear_dp);

  return 1;
}
Revision:	2.4
Committed:	Thu Aug 8 02:00:48 2024 UTC (8 months, 4 weeks ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.3:	+16 -11 lines
Log Message:	chore(genssky): Removed unsupported for() construct
#	User	Rev	Content
1	greg	2.2	#ifndef lint
2	greg	2.4	static const char RCSid[] = "$Id: genssky.c,v 2.3 2024/08/02 18:47:25 greg Exp $";
3	greg	2.2	#endif
4			/* Main function for generating spectral sky */
5			/* Cloudy sky computed as weight average of clear and cie overcast sky */
6	greg	2.1
7	greg	2.2	#include "atmos.h"
8	greg	2.1	#include "copyright.h"
9			#include "resolu.h"
10	greg	2.2	#include "rtio.h"
11			#include <ctype.h>
12			#ifdef _WIN32
13			#include <windows.h>
14			#else
15			#include <errno.h>
16			#include <sys/stat.h>
17			#include <sys/types.h>
18			#endif
19	greg	2.1
20			char *progname;
21
22			const double ARCTIC_LAT = 67.;
23			const double TROPIC_LAT = 23.;
24			const int SUMMER_START = 4;
25			const int SUMMER_END = 9;
26			const double GNORM = 0.777778;
27
28			const double D65EFF = 203.; /* standard illuminant D65 */
29
30	greg	2.2	/* Mean normalized relative daylight spectra where CCT = 6415K for overcast; */
31	greg	2.1	const double D6415[NSSAMP] = {0.63231, 1.06171, 1.00779, 1.36423, 1.34133,
32			1.27258, 1.26276, 1.26352, 1.22201, 1.13246,
33			1.0434, 1.05547, 0.98212, 0.94445, 0.9722,
34			0.82387, 0.87853, 0.82559, 0.75111, 0.78925};
35
36	greg	2.2	/* European and North American zones */
37			struct {
38			char zname[8]; /* time zone name (all caps) */
39			float zmer; /* standard meridian */
40			} tzone[] = {{"YST", 135}, {"YDT", 120}, {"PST", 120}, {"PDT", 105},
41			{"MST", 105}, {"MDT", 90}, {"CST", 90}, {"CDT", 75},
42			{"EST", 75}, {"EDT", 60}, {"AST", 60}, {"ADT", 45},
43			{"NST", 52.5}, {"NDT", 37.5}, {"GMT", 0}, {"BST", -15},
44			{"CET", -15}, {"CEST", -30}, {"EET", -30}, {"EEST", -45},
45			{"AST", -45}, {"ADT", -60}, {"GST", -60}, {"GDT", -75},
46			{"IST", -82.5}, {"IDT", -97.5}, {"JST", -135}, {"NDT", -150},
47			{"NZST", -180}, {"NZDT", -195}, {"", 0}};
48
49			static int make_directory(const char *path) {
50			#ifdef _WIN32
51			if (CreateDirectory(path, NULL) \|\| GetLastError() == ERROR_ALREADY_EXISTS) {
52			return 1;
53			}
54			return 0;
55			#else
56			if (mkdir(path, 0777) == 0 \|\| errno == EEXIST) {
57			return 1;
58			}
59			return 0;
60			#endif
61			}
62
63	greg	2.3	inline static float deg2rad(float deg) { return deg * (PI / 180.); }
64
65	greg	2.2	static int cvthour(char hs, int tsolar, double *hour) {
66			char *cp = hs;
67			int i, j;
68
69			if ((tsolar = cp == '+'))
70			cp++; /* solar time? */
71			while (isdigit(*cp))
72			cp++;
73			if (*cp == ':')
74			*hour = atoi(hs) + atoi(++cp) / 60.0;
75			else {
76			*hour = atof(hs);
77			if (*cp == '.')
78			cp++;
79			}
80			while (isdigit(*cp))
81			cp++;
82			if (!*cp)
83			return (0);
84			if (tsolar \|\| !isalpha(cp)) {
85			fprintf(stderr, "%s: bad time format: %s\n", progname, hs);
86			exit(1);
87			}
88			i = 0;
89			do {
90			for (j = 0; cp[j]; j++)
91			if (toupper(cp[j]) != tzone[i].zname[j])
92			break;
93			if (!cp[j] && !tzone[i].zname[j]) {
94			s_meridian = tzone[i].zmer * (PI / 180);
95			return (1);
96			}
97			} while (tzone[i++].zname[0]);
98
99			fprintf(stderr, "%s: unknown time zone: %s\n", progname, cp);
100			fprintf(stderr, "Known time zones:\n\t%s", tzone[0].zname);
101			for (i = 1; tzone[i].zname[0]; i++)
102			fprintf(stderr, " %s", tzone[i].zname);
103			putc('\n', stderr);
104			exit(1);
105			}
106
107			static void basename(const char path, char output, size_t outsize) {
108			const char *last_slash = strrchr(path, '/');
109			const char *last_backslash = strrchr(path, '\\');
110			const char *filename = path;
111			const char *last_dot;
112
113			if (last_slash && last_backslash) {
114			filename =
115			(last_slash > last_backslash) ? last_slash + 1 : last_backslash + 1;
116			} else if (last_slash) {
117			filename = last_slash + 1;
118			} else if (last_backslash) {
119			filename = last_backslash + 1;
120			}
121
122			last_dot = strrchr(filename, '.');
123			if (last_dot) {
124			size_t length = last_dot - filename;
125			if (length < outsize) {
126			strncpy(output, filename, length);
127			output[length] = '\0';
128			} else {
129			strncpy(output, filename, outsize - 1);
130			output[outsize - 1] = '\0';
131			}
132			}
133			}
134
135	greg	2.3	static char join_paths(const char path1, const char *path2) {
136	greg	2.2	size_t len1 = strlen(path1);
137			size_t len2 = strlen(path2);
138			int need_separator = (path1[len1 - 1] != DIRSEP);
139
140			char *result = malloc(len1 + len2 + (need_separator ? 2 : 1));
141			if (!result)
142			return NULL;
143
144			strcpy(result, path1);
145			if (need_separator) {
146			result[len1] = DIRSEP;
147			len1++;
148			}
149			strcpy(result + len1, path2);
150
151			return result;
152			}
153
154	greg	2.1	static inline double wmean2(const double a, const double b, const double x) {
155			return a * (1 - x) + b * x;
156			}
157
158			static inline double wmean(const double a, const double x, const double b,
159			const double y) {
160			return (a * x + b * y) / (a + b);
161			}
162
163			static double get_zenith_brightness(const double sundir[3]) {
164			double zenithbr;
165			if (sundir[2] < 0) {
166			zenithbr = 0;
167			} else {
168			zenithbr = (8.6 * sundir[2] + .123) * 1000.0 / D65EFF;
169			}
170			return zenithbr;
171			}
172
173	greg	2.2	/* from gensky.c */
174	greg	2.1	static double get_overcast_brightness(const double dz, const double zenithbr) {
175			double groundbr = zenithbr * GNORM;
176			return wmean(pow(dz + 1.01, 10), zenithbr * (1 + 2 * dz) / 3,
177			pow(dz + 1.01, -10), groundbr);
178			}
179
180	greg	2.2	static void write_header(const int argc, char **argv, const double cloud_cover,
181			const double grefl, const int res) {
182	greg	2.4	int i;
183	greg	2.2	printf("# ");
184	greg	2.4	for (i = 0; i < argc; i++) {
185	greg	2.2	printf("%s ", argv[i]);
186			}
187			printf("\n");
188	greg	2.3	printf(
189			"#Cloud cover: %g\n#Ground reflectance: %g\n#Sky map resolution: %d\n\n",
190			cloud_cover, grefl, res);
191	greg	2.2	}
192
193			static void write_rad(const double *sun_radiance, const FVECT sundir,
194	greg	2.3	const char ddir, const char skyfile) {
195	greg	2.1	if (sundir[2] > 0) {
196	greg	2.2	printf("void spectrum sunrad\n0\n0\n22 380 780 ");
197			/* Normalize to one */
198			double sum = 0.0;
199	greg	2.4	int i;
200			for (i = 0; i < NSSAMP; ++i) {
201	greg	2.2	sum += sun_radiance[i];
202	greg	2.1	}
203	greg	2.2	double mean = sum / NSSAMP;
204	greg	2.4	for (i = 0; i < NSSAMP; ++i) {
205	greg	2.2	printf("%.3f ", sun_radiance[i] / mean);
206			}
207			double intensity = mean * WVLSPAN;
208			printf("\n\nsunrad light solar\n0\n0\n3 %.1f %.1f %.1f\n\n", intensity,
209			intensity, intensity);
210			printf("solar source sun\n0\n0\n4 %f %f %f 0.533\n\n", sundir[0], sundir[1],
211			sundir[2]);
212			}
213	greg	2.3	printf("void specpict skyfunc\n5 noop %s . 'atan2(Dy,Dx)/PI+1' "
214			"'acos(Dz)/PI'\n0\n0\n\n",
215	greg	2.2	skyfile);
216	greg	2.1	}
217
218			static void write_hsr_header(FILE fp, RESOLU res) {
219	greg	2.3	float wvsplit[4] = {380, 480, 588, 780};
220	greg	2.1	newheader("RADIANCE", fp);
221			fputncomp(NSSAMP, fp);
222			fputwlsplit(wvsplit, fp);
223			fputformat(SPECFMT, fp);
224			fputc('\n', fp);
225			fputsresolu(res, fp);
226			}
227
228	greg	2.3	static inline float frac(float x) { return x - floor(x); }
229
230	greg	2.1	int gen_spect_sky(DATARRAY tau_clear, DATARRAY scat_clear,
231			DATARRAY scat1m_clear, DATARRAY irrad_clear,
232			const double cloud_cover, const FVECT sundir,
233	greg	2.3	const double grefl, const int res, const char *outname,
234			const char *ddir) {
235	greg	2.1	char skyfile[PATH_MAX];
236			char grndfile[PATH_MAX];
237	greg	2.3	if (!snprintf(skyfile, sizeof(skyfile), "%s%c%s_sky.hsr", ddir, DIRSEP,
238			outname)) {
239	greg	2.1	fprintf(stderr, "Error setting sky file name\n");
240			return 0;
241			};
242	greg	2.3	int xres = res;
243			int yres = xres / 2;
244			RESOLU rs = {PIXSTANDARD, xres, yres};
245	greg	2.1	FILE *skyfp = fopen(skyfile, "w");
246			write_hsr_header(skyfp, &rs);
247
248			CNDX[3] = NSSAMP;
249
250	greg	2.3	FVECT view_point = {0, 0, ER + 10};
251	greg	2.1	const double radius = VLEN(view_point);
252			const double sun_ct = fdot(view_point, sundir) / radius;
253	greg	2.4	int i, j, k;
254			for (j = 0; j < yres; ++j) {
255			for (i = 0; i < xres; ++i) {
256	greg	2.3	SCOLOR radiance = {0};
257	greg	2.1	SCOLR sky_sclr = {0};
258
259	greg	2.3	float px = i / (xres - 1.0);
260			float py = j / (yres - 1.0);
261			float lambda = ((1 - py) * PI) - (PI / 2.0);
262			float phi = (px * 2.0 * PI) - PI;
263
264			FVECT rdir = {cos(lambda) * cos(phi), cos(lambda) * sin(phi),
265			sin(lambda)};
266
267			const double mu = fdot(view_point, rdir) / radius;
268			const double nu = fdot(rdir, sundir);
269
270			/* hit ground */
271			if (rdir[2] < 0) {
272			get_ground_radiance(tau_clear, scat_clear, scat1m_clear, irrad_clear,
273			view_point, rdir, radius, mu, sun_ct, nu, grefl,
274			sundir, radiance);
275			} else {
276			get_sky_radiance(scat_clear, scat1m_clear, radius, mu, sun_ct, nu,
277			radiance);
278			}
279	greg	2.1
280	greg	2.4	for (k = 0; k < NSSAMP; ++k) {
281	greg	2.3	radiance[k] *= WVLSPAN;
282	greg	2.1	}
283
284			if (cloud_cover > 0) {
285			double zenithbr = get_zenith_brightness(sundir);
286			double grndbr = zenithbr * GNORM;
287	greg	2.3	double skybr = get_overcast_brightness(rdir[2], zenithbr);
288			if (rdir[2] < 0) {
289	greg	2.4	for (k = 0; k < NSSAMP; ++k) {
290	greg	2.3	radiance[k] = wmean2(radiance[k], grndbr * D6415[k], cloud_cover);
291			}
292			} else {
293	greg	2.4	for (k = 0; k < NSSAMP; ++k) {
294	greg	2.3	radiance[k] = wmean2(radiance[k], skybr * D6415[k], cloud_cover);
295			}
296	greg	2.1	}
297			}
298
299	greg	2.3	scolor2scolr(sky_sclr, radiance, 20);
300	greg	2.1	putbinary(sky_sclr, LSCOLR, 1, skyfp);
301			}
302			}
303			fclose(skyfp);
304
305	greg	2.2	/* Get solar radiance */
306	greg	2.1	double sun_radiance[NSSAMP] = {0};
307			get_solar_radiance(tau_clear, scat_clear, scat1m_clear, sundir, radius,
308			sun_ct, sun_radiance);
309			if (cloud_cover > 0) {
310			double zenithbr = get_zenith_brightness(sundir);
311			double skybr = get_overcast_brightness(sundir[2], zenithbr);
312	greg	2.4	int i;
313			for (i = 0; i < NSSAMP; ++i) {
314	greg	2.1	sun_radiance[i] =
315			wmean2(sun_radiance[i], D6415[i] * skybr / WVLSPAN, cloud_cover);
316			}
317			}
318
319	greg	2.3	write_rad(sun_radiance, sundir, ddir, skyfile);
320	greg	2.1	return 1;
321			}
322
323	greg	2.2	static DpPaths get_dppaths(const char dir, const double aod, const char mname,
324			const char *tag) {
325	greg	2.1	DpPaths paths;
326
327	greg	2.2	snprintf(paths.tau, PATH_MAX, "%s%ctau_%s_%s_%.2f.dat", dir, DIRSEP, tag,
328			mname, aod);
329			snprintf(paths.scat, PATH_MAX, "%s%cscat_%s_%s_%.2f.dat", dir, DIRSEP, tag,
330			mname, aod);
331			snprintf(paths.scat1m, PATH_MAX, "%s%cscat1m_%s_%s_%.2f.dat", dir, DIRSEP,
332			tag, mname, aod);
333			snprintf(paths.irrad, PATH_MAX, "%s%cirrad_%s_%s_%.2f.dat", dir, DIRSEP, tag,
334			mname, aod);
335	greg	2.1
336			return paths;
337			}
338
339	greg	2.2	static void set_rayleigh_density_profile(Atmosphere atmos, char tag,
340			const int is_summer,
341	greg	2.1	const double s_latitude) {
342	greg	2.2	if (fabs(s_latitude * 180.0 / PI) > ARCTIC_LAT) {
343	greg	2.1	tag[0] = 's';
344			if (is_summer) {
345			tag[1] = 's';
346			atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_SS;
347			atmos->beta_r0 = BR0_SS;
348			} else {
349			tag[1] = 'w';
350			atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_SW;
351			atmos->beta_r0 = BR0_SW;
352			}
353	greg	2.2	} else if (fabs(s_latitude * 180.0 / PI) > TROPIC_LAT) {
354	greg	2.1	tag[0] = 'm';
355			if (is_summer) {
356			tag[1] = 's';
357			atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_MS;
358			atmos->beta_r0 = BR0_MS;
359			} else {
360			tag[1] = 'w';
361			atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_MW;
362			atmos->beta_r0 = BR0_MW;
363			}
364			} else {
365			tag[0] = 't';
366			tag[1] = 'r';
367			atmos->rayleigh_density.layers[0].exp_scale = -1.0 / HR_T;
368			atmos->beta_r0 = BR0_T;
369			}
370			tag[2] = '\0';
371			}
372
373			static Atmosphere init_atmos(const double aod, const double grefl) {
374	greg	2.2	Atmosphere atmos = {.ozone_density = {.layers =
375			{
376			{.width = 25000.0,
377			.exp_term = 0.0,
378			.exp_scale = 0.0,
379			.linear_term = 1.0 / 15000.0,
380			.constant_term = -2.0 / 3.0},
381			{.width = AH,
382			.exp_term = 0.0,
383			.exp_scale = 0.0,
384			.linear_term = -1.0 / 15000.0,
385			.constant_term = 8.0 / 3.0},
386			}},
387			.rayleigh_density = {.layers =
388			{
389			{.width = AH,
390			.exp_term = 1.0,
391			.exp_scale = -1.0 / HR_MS,
392			.linear_term = 0.0,
393			.constant_term = 0.0},
394			}},
395			.beta_r0 = BR0_MS,
396			.beta_scale = aod / AOD0_CA,
397			.beta_m = NULL,
398			.grefl = grefl};
399	greg	2.1	return atmos;
400			}
401
402			int main(int argc, char *argv[]) {
403			progname = argv[0];
404			int month, day;
405			double hour;
406			FVECT sundir;
407			int num_threads = 1;
408			int sorder = 4;
409			int year = 0;
410			int tsolar = 0;
411	greg	2.2	int got_meridian = 0;
412	greg	2.1	double grefl = 0.2;
413			double ccover = 0.0;
414	greg	2.3	int res = 64;
415	greg	2.1	double aod = AOD0_CA;
416			char *outname = "out";
417			char *mie_path = getpath("mie_ca.dat", getrlibpath(), R_OK);
418	greg	2.2	char mie_name[20] = "mie_ca";
419	greg	2.1	char lstag[3];
420	greg	2.2	char *ddir = ".";
421	greg	2.4	int i;
422	greg	2.2
423	greg	2.3	if (argc == 2 && !strcmp(argv[1], "-defaults")) {
424	greg	2.2	printf("-i %d\t\t\t\t#scattering order\n", sorder);
425			printf("-g %f\t\t\t#ground reflectance\n", grefl);
426			printf("-c %f\t\t\t#cloud cover\n", ccover);
427			printf("-r %d\t\t\t\t#image resolution\n", res);
428			printf("-d %f\t\t\t#broadband aerosol optical depth\n", AOD0_CA);
429			printf("-f %s\t\t\t\t#output name (-f)\n", outname);
430			printf("-p %s\t\t\t\t#atmos data directory\n", ddir);
431	greg	2.3	exit(0);
432	greg	2.2	}
433	greg	2.1
434			if (argc < 4) {
435	greg	2.2	fprintf(stderr,
436			"Usage: %s month day hour -y year -a lat -o lon -m tz -d aod -r "
437			"res -n nproc -c ccover -l mie -g grefl -f outpath\n",
438	greg	2.1	argv[0]);
439			return 0;
440			}
441
442			month = atoi(argv[1]);
443	greg	2.2	if (month < 1 \|\| month > 12) {
444			fprintf(stderr, "bad month");
445			exit(1);
446			}
447	greg	2.1	day = atoi(argv[2]);
448	greg	2.2	if (day < 1 \|\| day > 31) {
449			fprintf(stderr, "bad month");
450			exit(1);
451			}
452			got_meridian = cvthour(argv[3], &tsolar, &hour);
453	greg	2.1
454			if (!compute_sundir(year, month, day, hour, tsolar, sundir)) {
455			fprintf(stderr, "Cannot compute solar angle\n");
456			exit(1);
457			}
458
459	greg	2.4	for (i = 4; i < argc; i++) {
460	greg	2.1	if (argv[i][0] == '-') {
461			switch (argv[i][1]) {
462			case 'a':
463			s_latitude = atof(argv[++i]) * (PI / 180.0);
464			break;
465			case 'c':
466			ccover = atof(argv[++i]);
467			break;
468			case 'd':
469			aod = atof(argv[++i]);
470			break;
471	greg	2.2	case 'f':
472			outname = argv[++i];
473			break;
474			case 'g':
475			grefl = atof(argv[++i]);
476			break;
477	greg	2.1	case 'i':
478			sorder = atoi(argv[++i]);
479			break;
480			case 'l':
481			mie_path = argv[++i];
482	greg	2.2	basename(mie_path, mie_name, sizeof(mie_name));
483	greg	2.1	break;
484			case 'm':
485	greg	2.2	if (got_meridian) {
486			++i;
487			break;
488			}
489	greg	2.1	s_meridian = atof(argv[++i]) * (PI / 180.0);
490			break;
491			case 'n':
492			num_threads = atoi(argv[++i]);
493			break;
494	greg	2.2	case 'o':
495			s_longitude = atof(argv[++i]) * (PI / 180.0);
496	greg	2.1	break;
497	greg	2.2	case 'p':
498			ddir = argv[++i];
499	greg	2.1	break;
500			case 'r':
501			res = atoi(argv[++i]);
502			break;
503	greg	2.2	case 'y':
504			year = atoi(argv[++i]);
505			break;
506	greg	2.1	default:
507			fprintf(stderr, "Unknown option %s\n", argv[i]);
508			exit(1);
509			}
510			}
511			}
512	greg	2.2	if (year && (year < 1950) \| (year > 2050))
513			fprintf(stderr, "%s: warning - year should be in range 1950-2050\n",
514			progname);
515			if (month && !tsolar && fabs(s_meridian - s_longitude) > 45 * PI / 180)
516			fprintf(stderr,
517			"%s: warning - %.1f hours btwn. standard meridian and longitude\n",
518			progname, (s_longitude - s_meridian) * 12 / PI);
519	greg	2.1
520			Atmosphere clear_atmos = init_atmos(aod, grefl);
521
522			int is_summer = (month >= SUMMER_START && month <= SUMMER_END);
523			if (s_latitude < 0) {
524			is_summer = !is_summer;
525			}
526			set_rayleigh_density_profile(&clear_atmos, lstag, is_summer, s_latitude);
527
528	greg	2.2	/* Load mie density data */
529	greg	2.1	DATARRAY *mie_dp = getdata(mie_path);
530			if (mie_dp == NULL) {
531			fprintf(stderr, "Error reading mie data\n");
532			return 0;
533			}
534			clear_atmos.beta_m = mie_dp;
535
536	greg	2.2	char gsdir[PATH_MAX];
537			size_t siz = strlen(ddir);
538	greg	2.3	if (ISDIRSEP(ddir[siz - 1]))
539			ddir[siz - 1] = '\0';
540	greg	2.2	snprintf(gsdir, PATH_MAX, "%s%catmos_data", ddir, DIRSEP);
541			if (!make_directory(gsdir)) {
542			fprintf(stderr, "Failed creating atmos_data directory");
543			exit(1);
544			}
545			DpPaths clear_paths = get_dppaths(gsdir, aod, mie_name, lstag);
546	greg	2.1
547			if (getpath(clear_paths.tau, ".", R_OK) == NULL \|\|
548			getpath(clear_paths.scat, ".", R_OK) == NULL \|\|
549			getpath(clear_paths.scat1m, ".", R_OK) == NULL \|\|
550			getpath(clear_paths.irrad, ".", R_OK) == NULL) {
551	greg	2.2	printf("# Pre-computing...\n");
552	greg	2.1	if (!precompute(sorder, clear_paths, &clear_atmos, num_threads)) {
553	greg	2.2	fprintf(stderr, "Pre-compute failed\n");
554	greg	2.1	return 0;
555			}
556			}
557
558			DATARRAY *tau_clear_dp = getdata(clear_paths.tau);
559			DATARRAY *irrad_clear_dp = getdata(clear_paths.irrad);
560			DATARRAY *scat_clear_dp = getdata(clear_paths.scat);
561			DATARRAY *scat1m_clear_dp = getdata(clear_paths.scat1m);
562
563	greg	2.2	write_header(argc, argv, ccover, grefl, res);
564
565	greg	2.1	if (!gen_spect_sky(tau_clear_dp, scat_clear_dp, scat1m_clear_dp,
566	greg	2.3	irrad_clear_dp, ccover, sundir, grefl, res, outname,
567			ddir)) {
568	greg	2.1	fprintf(stderr, "gen_spect_sky failed\n");
569			exit(1);
570			}
571
572			freedata(mie_dp);
573			freedata(tau_clear_dp);
574			freedata(scat_clear_dp);
575			freedata(irrad_clear_dp);
576			freedata(scat1m_clear_dp);
577
578			return 1;
579			}