2 // fg_time.cxx -- data structures and routines for managing time related stuff.
4 // Written by Curtis Olson, started August 1997.
6 // Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
8 // This program is free software; you can redistribute it and/or
9 // modify it under the terms of the GNU General Public License as
10 // published by the Free Software Foundation; either version 2 of the
11 // License, or (at your option) any later version.
13 // This program is distributed in the hope that it will be useful, but
14 // WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 // General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 // (Log is kept at end of this file)
35 #ifdef HAVE_SYS_TIMEB_H
36 # include <sys/timeb.h> // for ftime() and struct timeb
39 # include <unistd.h> // for gettimeofday()
41 #ifdef HAVE_SYS_TIME_H
42 # include <sys/time.h> // for get/setitimer, gettimeofday, struct timeval
45 #include <Debug/fg_debug.h>
46 #include <Flight/flight.h>
47 #include <Include/fg_constants.h>
48 #include <Main/options.hxx>
50 #include "fg_time.hxx"
53 #define DEGHR(x) ((x)/15.)
54 #define RADHR(x) DEGHR(x*RAD_TO_DEG)
56 // #define MK_TIME_IS_GMT 0 // default value
57 // #define TIME_ZONE_OFFSET_WORK 0 // default value
60 fgTIME cur_time_params;
63 // Initialize the time dependent variables
65 void fgTimeInit(fgTIME *t) {
66 fgPrintf( FG_EVENT, FG_INFO, "Initializing Time\n");
68 t->gst_diff = -9999.0;
70 fgPrintf( FG_EVENT, FG_DEBUG, "time offset = %d\n",
71 current_options.get_time_offset() );
73 t->warp = current_options.get_time_offset();
78 // Portability wrap to get current time.
79 void timestamp(fg_timestamp *timestamp) {
80 #if defined( HAVE_GETTIMEOFDAY )
81 struct timeval current;
83 // fg_timestamp currtime;
84 gettimeofday(¤t, &tz);
85 timestamp->seconds = current.tv_sec;
86 timestamp->millis = current.tv_usec / 1000;
87 #elif defined( HAVE_GETLOCALTIME )
89 GetLocalTime(¤t);
90 timestamp->seconds = current.wSecond;
91 timestamp->millis = current.wMilliseconds;
92 #elif defined( HAVE_FTIME )
95 timestamp->seconds = current.time;
96 timestamp->millis = current.millitm;
103 // Return duration in millis from first to last
104 long timediff(fg_timestamp *first, fg_timestamp *last) {
105 return 1000 * (last->seconds - first->seconds) +
106 (last->millis - first->millis);
110 // Return new timestamp given a time stamp and an interval to add in
111 void timesum(fg_timestamp *res, fg_timestamp *start, long millis) {
112 res->seconds = start->seconds +
113 ( start->millis + millis ) / 1000;
114 res->millis = ( start->millis + millis ) % 1000;
118 // given a date in months, mn, days, dy, years, yr, return the
119 // modified Julian date (number of days elapsed since 1900 jan 0.5),
120 // mjd. Adapted from Xephem.
122 double cal_mjd (int mn, double dy, int yr) {
123 static double last_mjd, last_dy;
125 static int last_mn, last_yr;
129 if (mn == last_mn && yr == last_yr && dy == last_dy) {
135 y = (yr < 0) ? yr + 1 : yr;
141 if (yr < 1582 || (yr == 1582 && (mn < 10 || (mn == 10 && dy < 15)))) {
150 c = (long)((365.25*y) - 0.75) - 694025L;
152 c = (long)(365.25*y) - 694025L;
155 d = (int)(30.6001*(m+1));
157 mjd = b + c + d + dy - 0.5;
168 // given an mjd, return greenwich mean siderial time, gst
170 double utc_gst (double mjd) {
172 double day = floor(mjd-0.5)+0.5;
173 double hr = (mjd-day)*24.0;
176 T = ((int)(mjd - 0.5) + 0.5 - J2000)/36525.0;
177 x = 24110.54841 + (8640184.812866 + (0.093104 - 6.2e-6 * T) * T) * T;
179 gst = (1.0/SIDRATE)*hr + x;
181 fgPrintf( FG_EVENT, FG_DEBUG, " gst => %.4f\n", gst);
187 // given Julian Date and Longitude (decimal degrees West) compute and
188 // return Local Sidereal Time, in decimal hours.
190 // Provided courtesy of ecdowney@noao.edu (Elwood Downey)
193 double sidereal_precise (double mjd, double lng) {
197 /* printf ("Current Lst on JD %13.5f at %8.4f degrees West: ",
200 // convert to required internal units
203 // compute LST and print
205 lst = gst - RADHR (lng);
206 lst -= 24.0*floor(lst/24.0);
207 // printf ("%7.4f\n", lst);
214 // Fix up timezone if using ftime()
215 long int fix_up_timezone( long int timezone_orig ) {
216 #if !defined( HAVE_GETTIMEOFDAY ) && defined( HAVE_FTIME )
217 // ftime() needs a little extra help finding the current timezone
218 struct timeb current;
220 return( current.timezone * 60 );
222 return( timezone_orig );
227 // Return time_t for Sat Mar 21 12:00:00 GMT
229 // I believe the mktime() has a SYSV vs. BSD behavior difference.
231 // The BSD style mktime() is nice because it returns its result
232 // assuming you have specified the input time in GMT
234 // The SYSV style mktime() is a pain because it returns its result
235 // assuming you have specified the input time in your local timezone.
236 // Therefore you have to go to extra trouble to convert back to GMT.
238 // If you are having problems with incorrectly positioned astronomical
239 // bodies, this is a really good place to start looking.
241 time_t get_start_gmt(int year) {
244 // For now we assume that if daylight is not defined in
245 // /usr/include/time.h that we have a machine with a BSD behaving
247 # if !defined(HAVE_DAYLIGHT)
248 # define MK_TIME_IS_GMT 1
251 // timezone seems to work as a proper offset for Linux & Solaris
252 # if defined( __linux__ ) || defined( __sun__ )
253 # define TIMEZONE_OFFSET_WORKS 1
262 mt.tm_isdst = -1; // let the system determine the proper time zone
264 # if defined( MK_TIME_IS_GMT )
265 return ( mktime(&mt) );
266 # else // ! defined ( MK_TIME_IS_GMT )
268 long int start = mktime(&mt);
270 fgPrintf( FG_EVENT, FG_DEBUG, "start1 = %ld\n", start);
271 fgPrintf( FG_EVENT, FG_DEBUG, "start2 = %s", ctime(&start));
272 fgPrintf( FG_EVENT, FG_DEBUG, "(tm_isdst = %d)\n", mt.tm_isdst);
274 timezone = fix_up_timezone( timezone );
276 # if defined( TIMEZONE_OFFSET_WORKS )
277 fgPrintf( FG_EVENT, FG_DEBUG,
278 "start = %ld, timezone = %ld\n", start, timezone );
279 return( start - timezone );
280 # else // ! defined( TIMEZONE_OFFSET_WORKS )
282 daylight = mt.tm_isdst;
283 if ( daylight > 0 ) {
285 } else if ( daylight < 0 ) {
286 fgPrintf( FG_EVENT, FG_WARN,
287 "OOOPS, problem in fg_time.cxx, no daylight savings info.\n");
290 long int offset = -(timezone / 3600 - daylight);
292 fgPrintf( FG_EVENT, FG_DEBUG,
293 " Raw time zone offset = %ld\n", timezone);
294 fgPrintf( FG_EVENT, FG_DEBUG,
295 " Daylight Savings = %d\n", daylight);
296 fgPrintf( FG_EVENT, FG_DEBUG,
297 " Local hours from GMT = %ld\n", offset);
299 long int start_gmt = start - timezone + (daylight * 3600);
301 fgPrintf( FG_EVENT, FG_DEBUG, " March 21 noon (CST) = %ld\n", start);
303 return ( start_gmt );
304 # endif // ! defined( TIMEZONE_OFFSET_WORKS )
305 # endif // ! defined ( MK_TIME_IS_GMT )
309 // return a courser but cheaper estimate of sidereal time
310 double sidereal_course(struct tm *gmt, time_t now, double lng) {
312 double diff, part, days, hours, lst;
314 start_gmt = get_start_gmt(gmt->tm_year);
316 fgPrintf(FG_EVENT, FG_DEBUG,
317 " COURSE: GMT = %d/%d/%2d %d:%02d:%02d\n",
318 gmt->tm_mon, gmt->tm_mday, gmt->tm_year,
319 gmt->tm_hour, gmt->tm_min, gmt->tm_sec);
321 fgPrintf( FG_EVENT, FG_DEBUG, " March 21 noon (GMT) = %ld\n", start_gmt);
323 diff = (now - start_gmt) / (3600.0 * 24.0);
325 fgPrintf( FG_EVENT, FG_DEBUG,
326 " Time since 3/21/%2d GMT = %.2f\n", gmt->tm_year, diff);
328 part = fmod(diff, 1.0);
330 hours = gmt->tm_hour + gmt->tm_min/60.0 + gmt->tm_sec/3600.0;
332 lst = (days - lng)/15.0 + hours - 12;
334 while ( lst < 0.0 ) {
338 fgPrintf( FG_EVENT, FG_DEBUG,
339 " days = %.1f hours = %.2f lon = %.2f lst = %.2f\n",
340 days, hours, lng, lst);
346 // Update time variables such as gmt, julian date, and sidereal time
347 void fgTimeUpdate(fgFLIGHT *f, fgTIME *t) {
348 double gst_precise, gst_course;
350 fgPrintf( FG_EVENT, FG_BULK, "Updating time\n");
352 // get current Unix calendar time (in seconds)
353 t->warp += t->warp_delta;
354 t->cur_time = time(NULL) + t->warp;
355 fgPrintf( FG_EVENT, FG_BULK,
356 " Current Unix calendar time = %ld warp = %ld delta = %ld\n",
357 t->cur_time, t->warp, t->warp_delta);
359 // get GMT break down for current time
360 t->gmt = gmtime(&t->cur_time);
361 fgPrintf( FG_EVENT, FG_BULK,
362 " Current GMT = %d/%d/%2d %d:%02d:%02d\n",
363 t->gmt->tm_mon+1, t->gmt->tm_mday, t->gmt->tm_year,
364 t->gmt->tm_hour, t->gmt->tm_min, t->gmt->tm_sec);
366 // calculate modified Julian date
367 t->mjd = cal_mjd ((int)(t->gmt->tm_mon+1), (double)t->gmt->tm_mday,
368 (int)(t->gmt->tm_year + 1900));
370 // add in partial day
371 t->mjd += (t->gmt->tm_hour / 24.0) + (t->gmt->tm_min / (24.0 * 60.0)) +
372 (t->gmt->tm_sec / (24.0 * 60.0 * 60.0));
374 // convert "back" to Julian date + partial day (as a fraction of one)
375 t->jd = t->mjd + MJD0;
376 fgPrintf( FG_EVENT, FG_BULK, " Current Julian Date = %.5f\n", t->jd);
378 // printf(" Current Longitude = %.3f\n", FG_Longitude * RAD_TO_DEG);
380 // Calculate local side real time
381 if ( t->gst_diff < -100.0 ) {
382 // first time through do the expensive calculation & cheap
383 // calculation to get the difference.
384 fgPrintf( FG_EVENT, FG_INFO, " First time, doing precise gst\n");
385 t->gst = gst_precise = sidereal_precise(t->mjd, 0.00);
386 gst_course = sidereal_course(t->gmt, t->cur_time, 0.00);
387 t->gst_diff = gst_precise - gst_course;
390 sidereal_course(t->gmt, t->cur_time, -(FG_Longitude * RAD_TO_DEG))
393 // course + difference should drift off very slowly
395 sidereal_course(t->gmt, t->cur_time, 0.00) + t->gst_diff;
397 sidereal_course(t->gmt, t->cur_time, -(FG_Longitude * RAD_TO_DEG))
400 fgPrintf( FG_EVENT, FG_DEBUG,
401 " Current lon=0.00 Sidereal Time = %.3f\n", t->gst);
402 fgPrintf( FG_EVENT, FG_DEBUG,
403 " Current LOCAL Sidereal Time = %.3f (%.3f) (diff = %.3f)\n",
404 t->lst, sidereal_precise(t->mjd, -(FG_Longitude * RAD_TO_DEG)),
410 // Revision 1.10 1998/07/13 21:02:07 curt
411 // Wrote access functions for current fgOPTIONS.
413 // Revision 1.9 1998/06/12 00:59:53 curt
414 // Build only static libraries.
415 // Declare memmove/memset for Sloaris.
416 // Rewrote fg_time.c routine to get LST start seconds to better handle
417 // Solaris, and be easier to port, and understand the GMT vs. local
420 // Revision 1.8 1998/06/05 18:18:13 curt
421 // Incorporated some automake conditionals to try to support mktime() correctly
422 // on a wider variety of platforms.
423 // Added the declaration of memmove needed by the stl which apparently
424 // solaris only defines for cc compilations and not for c++ (__STDC__)
426 // Revision 1.7 1998/05/30 01:57:25 curt
429 // Revision 1.6 1998/05/02 01:53:17 curt
430 // Fine tuning mktime() support because of varying behavior on different
433 // Revision 1.5 1998/04/28 21:45:34 curt
434 // Fixed a horible bug that cause the time to be *WAY* off when compiling
435 // with the CygWin32 compiler. This may not yet completely address other
436 // Win32 compilers, but we'll have to take them on a case by case basis.
438 // Revision 1.4 1998/04/28 01:22:16 curt
439 // Type-ified fgTIME and fgVIEW.
441 // Revision 1.3 1998/04/25 22:06:33 curt
442 // Edited cvs log messages in source files ... bad bad bad!
444 // Revision 1.2 1998/04/25 20:24:02 curt
445 // Cleaned up initialization sequence to eliminate interdependencies
446 // between sun position, lighting, and view position. This creates a
447 // valid single pass initialization path.
449 // Revision 1.1 1998/04/24 00:52:27 curt
450 // Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
452 // Separated out lighting calcs into their own file.
454 // Revision 1.41 1998/04/22 13:24:05 curt
455 // C++ - ifiing the code a bit.
456 // Starting to reorginize some of the lighting calcs to use a table lookup.
458 // Revision 1.40 1998/04/18 04:14:09 curt
459 // Moved fg_debug.c to it's own library.
461 // Revision 1.39 1998/04/09 18:40:14 curt
462 // We had unified some of the platform disparate time handling code, and
463 // there was a bug in timesum() which calculated a new time stamp based on
464 // the current time stamp + offset. This hosed the periodic event processing
465 // logic because you'd never arrive at the time the event was scheduled for.
466 // Sky updates and lighting changes are handled via this event mechanism so
467 // they never changed ... it is fixed now.
469 // Revision 1.38 1998/04/08 23:35:40 curt
470 // Tweaks to Gnu automake/autoconf system.
472 // Revision 1.37 1998/04/03 22:12:55 curt
473 // Converting to Gnu autoconf system.
474 // Centralized time handling differences.
476 // Revision 1.36 1998/03/09 22:48:09 curt
477 // Debug message tweaks.
479 // Revision 1.35 1998/02/09 15:07:52 curt
482 // Revision 1.34 1998/02/07 15:29:47 curt
483 // Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
484 // <chotchkiss@namg.us.anritsu.com>
486 // Revision 1.33 1998/02/02 20:54:04 curt
487 // Incorporated Durk's changes.
489 // Revision 1.32 1998/02/01 03:39:56 curt
492 // Revision 1.31 1998/01/27 00:48:06 curt
493 // Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
494 // system and commandline/config file processing code.
496 // Revision 1.30 1998/01/21 21:11:35 curt
499 // Revision 1.29 1998/01/19 19:27:20 curt
500 // Merged in make system changes from Bob Kuehne <rpk@sgi.com>
501 // This should simplify things tremendously.
503 // Revision 1.28 1998/01/19 18:35:49 curt
504 // Minor tweaks and fixes for cygwin32.
506 // Revision 1.27 1998/01/13 00:23:13 curt
507 // Initial changes to support loading and management of scenery tiles. Note,
508 // there's still a fair amount of work left to be done.
510 // Revision 1.26 1998/01/05 18:44:36 curt
511 // Add an option to advance/decrease time from keyboard.
513 // Revision 1.25 1997/12/31 17:46:50 curt
514 // Tweaked fg_time.c to be able to use ftime() instead of gettimeofday()
516 // Revision 1.24 1997/12/30 22:22:42 curt
517 // Further integration of event manager.
519 // Revision 1.23 1997/12/30 20:47:58 curt
520 // Integrated new event manager with subsystem initializations.
522 // Revision 1.22 1997/12/30 01:38:47 curt
523 // Switched back to per vertex normals and smooth shading for terrain.
525 // Revision 1.21 1997/12/23 04:58:39 curt
526 // Tweaked the sky coloring a bit to build in structures to allow finer rgb
529 // Revision 1.20 1997/12/15 23:55:06 curt
530 // Add xgl wrappers for debugging.
531 // Generate terrain normals on the fly.
533 // Revision 1.19 1997/12/15 20:59:10 curt
536 // Revision 1.18 1997/12/12 21:41:31 curt
537 // More light/material property tweaking ... still a ways off.
539 // Revision 1.17 1997/12/12 19:53:04 curt
540 // Working on lightling and material properties.
542 // Revision 1.16 1997/12/11 04:43:57 curt
543 // Fixed sun vector and lighting problems. I thing the moon is now lit
546 // Revision 1.15 1997/12/10 22:37:54 curt
547 // Prepended "fg" on the name of all global structures that didn't have it yet.
548 // i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
550 // Revision 1.14 1997/12/10 01:19:52 curt
551 // Tweaks for verion 0.15 release.
553 // Revision 1.13 1997/12/09 05:11:56 curt
554 // Working on tweaking lighting.
556 // Revision 1.12 1997/12/09 04:25:37 curt
557 // Working on adding a global lighting params structure.
559 // Revision 1.11 1997/11/25 19:25:40 curt
560 // Changes to integrate Durk's moon/sun code updates + clean up.
562 // Revision 1.10 1997/11/15 18:16:42 curt
565 // Revision 1.9 1997/11/14 00:26:50 curt
566 // Transform scenery coordinates earlier in pipeline when scenery is being
567 // created, not when it is being loaded. Precalculate normals for each node
568 // as average of the normals of each containing polygon so Garoude shading is
571 // Revision 1.8 1997/10/25 03:30:08 curt
574 // Revision 1.7 1997/09/23 00:29:50 curt
575 // Tweaks to get things to compile with gcc-win32.
577 // Revision 1.6 1997/09/20 03:34:34 curt
578 // Still trying to get those durned stars aligned properly.
580 // Revision 1.5 1997/09/16 22:14:52 curt
581 // Tweaked time of day lighting equations. Don't draw stars during the day.
583 // Revision 1.4 1997/09/16 15:50:31 curt
584 // Working on star alignment and time issues.
586 // Revision 1.3 1997/09/13 02:00:08 curt
587 // Mostly working on stars and generating sidereal time for accurate star
590 // Revision 1.2 1997/08/27 03:30:35 curt
591 // Changed naming scheme of basic shared structures.
593 // Revision 1.1 1997/08/13 21:55:59 curt