star-cem

commit c9cc62400169dfa00258e4b10afa5615ac15f3fe
parent 5c0a994016088d8e1c89c577ad61935590aa6260
Author: Vincent Forest <vincent.forest@meso-star.com>
Date:   Wed,  8 Oct 2025 09:29:44 +0200

Finalize the implementation of the scem tool

Use the scem library to calculate the position of the sun.

Add the verbose option which, when enabled, displays the UTC+00:00 date
at which the position of the sun is calculated.

Diffstat:
M
doc/scem.1
 | 
7
++++++-
M
src/scem_main.c
 | 
40
++++++++++++++++++++++++++++++++++++++--

2 files changed, 44 insertions(+), 3 deletions(-)
diff --git a/doc/scem.1 b/doc/scem.1
@@ -23,7 +23,7 @@
 .\""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""
 .Sh SYNOPSIS
 .Nm
-.Op Fl hr
+.Op Fl hvr
 .Op Fl a Ar algo
 .Op Fl d Ar utc_date
 .Ar latitude
@@ -99,6 +99,11 @@ date -u +"%Y-%m-%dT%H:%M:%S"
 .It Fl h
 Output short help and exit.
 .\""""""""""""""""""""""""""""""""""""""
+.It Fl v
+Make
+.Nm
+verbose.
+.\""""""""""""""""""""""""""""""""""""""
 .It Fl r
 The solar output coordinates are defined in radians rather than degrees.
 .El
diff --git a/src/scem_main.c b/src/scem_main.c
@@ -31,10 +31,11 @@ struct args {
   struct tm time; /* In UTC+00:00 */
   enum scem_sun_algo algo;
   int radian; /* Sun position in radians instead of degrees */
+  int verbose;
   int quit;
 };
 static const struct args ARGS_DEFAULT = {
-  SCEM_LOCATION_NULL__, {0}, SCEM_SUN_MEEUS, 0, 0
+  SCEM_LOCATION_NULL__, {0}, SCEM_SUN_MEEUS, 0, 0, 0
 };
 
 /*******************************************************************************
@@ -93,6 +94,22 @@ parse_dbl
 }
 
 static res_T
+get_current_date(struct tm* date)
+{
+  time_t epoch;
+  ASSERT(date);
+
+  epoch = time(NULL);
+  if(epoch == (time_t)-1) {
+    fprintf(stderr, "scem: error in querying local time\n");
+    return RES_BAD_ARG;
+  }
+
+  *date = *gmtime(&epoch);
+  return RES_OK;
+}
+
+static res_T
 args_init(struct args* args, int argc, char** argv)
 {
   int opt = 0;
@@ -100,11 +117,14 @@ args_init(struct args* args, int argc, char** argv)
 
   *args = ARGS_DEFAULT;
 
-  while((opt = getopt(argc, argv, "a:d:hr")) != -1) {
+  if((res = get_current_date(&args->time)) != RES_OK) goto error;
+
+  while((opt = getopt(argc, argv, "a:d:hvr")) != -1) {
     switch(opt) {
       case 'a': res = parse_algo(optarg, &args->algo); break;
       case 'd': res = parse_date(optarg, &args->time); break;
       case 'h': usage(stdout); args->quit = 1; goto exit;
+      case 'v': args->verbose = 1; break;
       case 'r': args->radian = 1; break;
       default: res = RES_BAD_ARG; break;
     }
@@ -138,12 +158,28 @@ int
 main(int argc, char** argv)
 {
   struct args args = ARGS_DEFAULT;
+  struct scem_sun_pos pos = SCEM_SUN_POS_NULL;
   int err = 0;
   res_T res = RES_OK;
 
   if((res = args_init(&args, argc, argv)) != RES_OK) goto error;
   if(args.quit) goto exit;
 
+  if(args.verbose) fprintf(stderr, "%s", asctime(&args.time));
+
+  res = scem_sun_position_from_earth(&args.time, &args.pos, args.algo, &pos);
+  if(res != RES_OK) {
+    fprintf(stderr, "scem: error in computing the position of sun -- %s\n",
+      res_to_cstr(res));
+    goto error;
+  }
+
+  if(args.radian) {
+    printf("%g %g\n", pos.zenith, pos.azimuth);
+  } else {
+    printf("%g %g\n", MRAD2DEG(pos.zenith), MRAD2DEG(pos.azimuth));
+  }
+
 exit:
   CHK(mem_allocated_size() == 0);
   return err;