1 // fg_time.cxx -- data structures and routines for managing time related stuff.
3 // Written by Curtis Olson, started August 1997.
5 // Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
7 // This program is free software; you can redistribute it and/or
8 // modify it under the terms of the GNU General Public License as
9 // published by the Free Software Foundation; either version 2 of the
10 // License, or (at your option) any later version.
12 // This program is distributed in the hope that it will be useful, but
13 // WITHOUT ANY WARRANTY; without even the implied warranty of
14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 // General Public License for more details.
17 // You should have received a copy of the GNU General Public License
18 // along with this program; if not, write to the Free Software
19 // Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 // (Log is kept at end of this file)
29 #include <Include/compiler.h>
31 #ifdef FG_HAVE_STD_INCLUDES
43 #ifdef HAVE_SYS_TIMEB_H
44 # include <sys/timeb.h> // for ftime() and struct timeb
47 # include <unistd.h> // for gettimeofday()
49 #ifdef HAVE_SYS_TIME_H
50 # include <sys/time.h> // for get/setitimer, gettimeofday, struct timeval
53 #include <Debug/logstream.hxx>
54 #include <Astro/sky.hxx>
55 #include <Astro/solarsystem.hxx>
56 #include <FDM/flight.hxx>
57 #include <Include/fg_constants.h>
58 #include <Main/options.hxx>
59 #include <Time/light.hxx>
61 #include "fg_time.hxx"
64 #define DEGHR(x) ((x)/15.)
65 #define RADHR(x) DEGHR(x*RAD_TO_DEG)
67 // #define MK_TIME_IS_GMT 0 // default value
68 // #define TIME_ZONE_OFFSET_WORK 0 // default value
71 fgTIME cur_time_params;
74 // Force an update of the sky and lighting parameters
75 static void local_update_sky_and_lighting_params( void ) {
77 SolarSystem::theSolarSystem->rebuild();
78 cur_light_params.Update();
83 // Initialize the time dependent variables
84 void fgTimeInit(fgTIME *t) {
85 FG_LOG( FG_EVENT, FG_INFO, "Initializing Time" );
87 t->gst_diff = -9999.0;
89 FG_LOG( FG_EVENT, FG_DEBUG,
90 "time offset = " << current_options.get_time_offset() );
92 t->warp = current_options.get_time_offset();
95 t->pause = current_options.get_pause();
99 // given a date in months, mn, days, dy, years, yr, return the
100 // modified Julian date (number of days elapsed since 1900 jan 0.5),
101 // mjd. Adapted from Xephem.
103 double cal_mjd (int mn, double dy, int yr) {
104 static double last_mjd, last_dy;
106 static int last_mn, last_yr;
110 if (mn == last_mn && yr == last_yr && dy == last_dy) {
116 y = (yr < 0) ? yr + 1 : yr;
122 if (yr < 1582 || (yr == 1582 && (mn < 10 || (mn == 10 && dy < 15)))) {
131 c = (long)((365.25*y) - 0.75) - 694025L;
133 c = (long)(365.25*y) - 694025L;
136 d = (int)(30.6001*(m+1));
138 mjd = b + c + d + dy - 0.5;
149 // given an mjd, return greenwich mean sidereal time, gst
151 double utc_gst (double mjd) {
153 double day = floor(mjd-0.5)+0.5;
154 double hr = (mjd-day)*24.0;
157 T = ((int)(mjd - 0.5) + 0.5 - J2000)/36525.0;
158 x = 24110.54841 + (8640184.812866 + (0.093104 - 6.2e-6 * T) * T) * T;
160 gst = (1.0/SIDRATE)*hr + x;
162 FG_LOG( FG_EVENT, FG_DEBUG, " gst => " << gst );
168 // given Julian Date and Longitude (decimal degrees West) compute and
169 // return Local Sidereal Time, in decimal hours.
171 // Provided courtesy of ecdowney@noao.edu (Elwood Downey)
174 double sidereal_precise (double mjd, double lng) {
178 /* printf ("Current Lst on JD %13.5f at %8.4f degrees West: ",
181 // convert to required internal units
184 // compute LST and print
186 lst = gst - RADHR (lng);
187 lst -= 24.0*floor(lst/24.0);
188 // printf ("%7.4f\n", lst);
195 // Fix up timezone if using ftime()
196 long int fix_up_timezone( long int timezone_orig ) {
197 #if !defined( HAVE_GETTIMEOFDAY ) && defined( HAVE_FTIME )
198 // ftime() needs a little extra help finding the current timezone
199 struct timeb current;
201 return( current.timezone * 60 );
203 return( timezone_orig );
208 // Return time_t for Sat Mar 21 12:00:00 GMT
210 // I believe the mktime() has a SYSV vs. BSD behavior difference.
212 // The BSD style mktime() is nice because it returns its result
213 // assuming you have specified the input time in GMT
215 // The SYSV style mktime() is a pain because it returns its result
216 // assuming you have specified the input time in your local timezone.
217 // Therefore you have to go to extra trouble to convert back to GMT.
219 // If you are having problems with incorrectly positioned astronomical
220 // bodies, this is a really good place to start looking.
222 time_t get_start_gmt(int year) {
225 // For now we assume that if daylight is not defined in
226 // /usr/include/time.h that we have a machine with a BSD behaving
228 # if !defined(HAVE_DAYLIGHT)
229 # define MK_TIME_IS_GMT 1
232 // timezone seems to work as a proper offset for Linux & Solaris
233 # if defined( __linux__ ) || defined( __sun__ )
234 # define TIMEZONE_OFFSET_WORKS 1
243 mt.tm_isdst = -1; // let the system determine the proper time zone
245 # if defined( MK_TIME_IS_GMT )
246 return ( mktime(&mt) );
247 # else // ! defined ( MK_TIME_IS_GMT )
249 long int start = mktime(&mt);
251 FG_LOG( FG_EVENT, FG_DEBUG, "start1 = " << start );
252 // the ctime() call can screw up time progression on some versions
254 // fgPrintf( FG_EVENT, FG_DEBUG, "start2 = %s", ctime(&start));
255 FG_LOG( FG_EVENT, FG_DEBUG, "(tm_isdst = " << mt.tm_isdst << ")" );
257 timezone = fix_up_timezone( timezone );
259 # if defined( TIMEZONE_OFFSET_WORKS )
260 FG_LOG( FG_EVENT, FG_DEBUG,
261 "start = " << start << ", timezone = " << timezone );
262 return( start - timezone );
263 # else // ! defined( TIMEZONE_OFFSET_WORKS )
265 daylight = mt.tm_isdst;
266 if ( daylight > 0 ) {
268 } else if ( daylight < 0 ) {
269 FG_LOG( FG_EVENT, FG_WARN,
270 "OOOPS, problem in fg_time.cxx, no daylight savings info." );
273 long int offset = -(timezone / 3600 - daylight);
275 FG_LOG( FG_EVENT, FG_DEBUG, " Raw time zone offset = " << timezone );
276 FG_LOG( FG_EVENT, FG_DEBUG, " Daylight Savings = " << daylight );
277 FG_LOG( FG_EVENT, FG_DEBUG, " Local hours from GMT = " << offset );
279 long int start_gmt = start - timezone + (daylight * 3600);
281 FG_LOG( FG_EVENT, FG_DEBUG, " March 21 noon (CST) = " << start );
283 return ( start_gmt );
284 # endif // ! defined( TIMEZONE_OFFSET_WORKS )
285 # endif // ! defined ( MK_TIME_IS_GMT )
289 format_time( const struct tm* p, char* buf )
291 sprintf( buf, "%d/%d/%2d %d:%02d:%02d",
292 p->tm_mon, p->tm_mday, p->tm_year,
293 p->tm_hour, p->tm_min, p->tm_sec);
297 // return a courser but cheaper estimate of sidereal time
298 double sidereal_course(fgTIME *t, double lng) {
300 time_t start_gmt, now;
301 double diff, part, days, hours, lst;
306 start_gmt = get_start_gmt(gmt->tm_year);
308 FG_LOG( FG_EVENT, FG_DEBUG, " COURSE: GMT = " << format_time(gmt, tbuf) );
309 FG_LOG( FG_EVENT, FG_DEBUG, " March 21 noon (GMT) = " << start_gmt );
311 diff = (now - start_gmt) / (3600.0 * 24.0);
313 FG_LOG( FG_EVENT, FG_DEBUG,
314 " Time since 3/21/" << gmt->tm_year << " GMT = " << diff );
316 part = fmod(diff, 1.0);
318 hours = gmt->tm_hour + gmt->tm_min/60.0 + gmt->tm_sec/3600.0;
320 lst = (days - lng)/15.0 + hours - 12;
322 while ( lst < 0.0 ) {
326 FG_LOG( FG_EVENT, FG_DEBUG,
327 " days = " << days << " hours = " << hours << " lon = "
328 << lng << " lst = " << lst );
334 // Update time variables such as gmt, julian date, and sidereal time
335 void fgTimeUpdate(FGInterface *f, fgTIME *t) {
336 double gst_precise, gst_course;
338 FG_LOG( FG_EVENT, FG_DEBUG, "Updating time" );
340 // get current Unix calendar time (in seconds)
341 t->warp += t->warp_delta;
342 t->cur_time = time(NULL) + t->warp;
343 FG_LOG( FG_EVENT, FG_DEBUG,
344 " Current Unix calendar time = " << t->cur_time
345 << " warp = " << t->warp << " delta = " << t->warp_delta );
347 if ( t->warp_delta ) {
348 // time is changing so force an update
349 local_update_sky_and_lighting_params();
352 // get GMT break down for current time
353 t->gmt = gmtime(&t->cur_time);
354 FG_LOG( FG_EVENT, FG_DEBUG,
355 " Current GMT = " << t->gmt->tm_mon+1 << "/"
356 << t->gmt->tm_mday << "/" << t->gmt->tm_year << " "
357 << t->gmt->tm_hour << ":" << t->gmt->tm_min << ":"
360 // calculate modified Julian date
361 t->mjd = cal_mjd ((int)(t->gmt->tm_mon+1), (double)t->gmt->tm_mday,
362 (int)(t->gmt->tm_year + 1900));
364 // add in partial day
365 t->mjd += (t->gmt->tm_hour / 24.0) + (t->gmt->tm_min / (24.0 * 60.0)) +
366 (t->gmt->tm_sec / (24.0 * 60.0 * 60.0));
368 // convert "back" to Julian date + partial day (as a fraction of one)
369 t->jd = t->mjd + MJD0;
370 FG_LOG( FG_EVENT, FG_DEBUG, " Current Julian Date = " << t->jd );
372 // printf(" Current Longitude = %.3f\n", FG_Longitude * RAD_TO_DEG);
374 // Calculate local side real time
375 if ( t->gst_diff < -100.0 ) {
376 // first time through do the expensive calculation & cheap
377 // calculation to get the difference.
378 FG_LOG( FG_EVENT, FG_INFO, " First time, doing precise gst" );
379 t->gst = gst_precise = sidereal_precise(t->mjd, 0.00);
380 gst_course = sidereal_course(t, 0.00);
381 t->gst_diff = gst_precise - gst_course;
384 sidereal_course(t, -(f->get_Longitude() * RAD_TO_DEG)) + t->gst_diff;
386 // course + difference should drift off very slowly
387 t->gst = sidereal_course(t, 0.00) + t->gst_diff;
388 t->lst = sidereal_course(t, -(f->get_Longitude() * RAD_TO_DEG)) +
391 FG_LOG( FG_EVENT, FG_DEBUG,
392 " Current lon=0.00 Sidereal Time = " << t->gst );
393 FG_LOG( FG_EVENT, FG_DEBUG,
394 " Current LOCAL Sidereal Time = " << t->lst << " ("
395 << sidereal_precise(t->mjd, -(f->get_Longitude() * RAD_TO_DEG))
396 << ") (diff = " << t->gst_diff << ")" );
401 // Revision 1.2 1999/04/06 16:58:34 curt
402 // Clean ups and reorganizations:
403 // - Additional Thanks entry
404 // - more info on getting gfc library
405 // - converted some C style comments to C++ style.
407 // Revision 1.1.1.1 1999/04/05 21:32:47 curt
408 // Start of 0.6.x branch.
410 // Revision 1.32 1999/02/26 22:10:10 curt
411 // Added initial support for native SGI compilers.
413 // Revision 1.31 1999/02/05 21:29:18 curt
414 // Modifications to incorporate Jon S. Berndts flight model code.
416 // Revision 1.30 1999/02/01 21:33:37 curt
417 // Renamed FlightGear/Simulator/Flight to FlightGear/Simulator/FDM since
418 // Jon accepted my offer to do this and thought it was a good idea.
420 // Revision 1.29 1999/01/19 20:57:08 curt
421 // MacOS portability changes contributed by "Robert Puyol" <puyol@abvent.fr>
423 // Revision 1.28 1999/01/07 20:25:34 curt
424 // Portability changes and updates from Bernie Bright.
426 // Revision 1.27 1998/12/11 20:26:55 curt
429 // Revision 1.26 1998/12/05 15:54:28 curt
430 // Renamed class fgFLIGHT to class FGState as per request by JSB.
432 // Revision 1.25 1998/12/05 14:21:30 curt
433 // Moved struct fg_timestamp to class fgTIMESTAMP and moved it's definition
434 // to it's own file, timestamp.hxx.
436 // Revision 1.24 1998/12/04 01:32:49 curt
437 // Converted "struct fg_timestamp" to "class fgTIMESTAMP" and added some
438 // convenience inline operators.
440 // Revision 1.23 1998/12/03 01:18:40 curt
441 // Converted fgFLIGHT to a class.
443 // Revision 1.22 1998/11/16 14:00:28 curt
444 // FG_LOG() message tweaks.
446 // Revision 1.21 1998/11/06 21:18:26 curt
447 // Converted to new logstream debugging facility. This allows release
448 // builds with no messages at all (and no performance impact) by using
449 // the -DFG_NDEBUG flag.
451 // Revision 1.20 1998/11/02 18:25:38 curt
452 // Check for __CYGWIN__ (b20) as well as __CYGWIN32__ (pre b20 compilers)
453 // Other misc. tweaks.
455 // Revision 1.19 1998/10/17 01:34:29 curt
458 // Revision 1.18 1998/10/02 21:36:09 curt
459 // Fixes to try to break through the win95/98 18.3 fps barrier.
461 // Revision 1.17 1998/09/15 04:27:49 curt
462 // Changes for new astro code.
464 // Revision 1.16 1998/08/29 13:11:32 curt
465 // Bernie Bright writes:
466 // I've created some new classes to enable pointers-to-functions and
467 // pointers-to-class-methods to be treated like objects. These objects
468 // can be registered with fgEVENT_MGR.
470 // File "Include/fg_callback.hxx" contains the callback class defns.
472 // Modified fgEVENT and fgEVENT_MGR to use the callback classes. Also
473 // some minor tweaks to STL usage.
475 // Added file "Include/fg_stl_config.h" to deal with STL portability
476 // issues. I've added an initial config for egcs (and probably gcc-2.8.x).
477 // I don't have access to Visual C++ so I've left that for someone else.
478 // This file is influenced by the stl_config.h file delivered with egcs.
480 // Added "Include/auto_ptr.hxx" which contains an implementation of the
481 // STL auto_ptr class which is not provided in all STL implementations
482 // and is needed to use the callback classes.
484 // Deleted fgLightUpdate() which was just a wrapper to call
485 // fgLIGHT::Update().
487 // Modified fg_init.cxx to register two method callbacks in place of the
488 // old wrapper functions.
490 // Revision 1.15 1998/08/24 20:12:16 curt
491 // Rewrote sidereal_course with simpler parameters.
493 // Revision 1.14 1998/08/05 00:20:07 curt
494 // Added a local routine to update lighting params every frame when time is
497 // Revision 1.13 1998/07/30 23:48:55 curt
501 // Revision 1.12 1998/07/27 18:42:22 curt
502 // Added a pause option.
504 // Revision 1.11 1998/07/22 21:45:37 curt
505 // fg_time.cxx: Removed call to ctime() in a printf() which should be harmless
506 // but seems to be triggering a bug.
507 // light.cxx: Added code to adjust fog color based on sunrise/sunset effects
508 // and view orientation. This is an attempt to match the fog color to the
509 // sky color in the center of the screen. You see discrepancies at the
510 // edges, but what else can be done?
511 // sunpos.cxx: Caculate local direction to sun here. (what compass direction
512 // do we need to face to point directly at sun)
514 // Revision 1.10 1998/07/13 21:02:07 curt
515 // Wrote access functions for current fgOPTIONS.
517 // Revision 1.9 1998/06/12 00:59:53 curt
518 // Build only static libraries.
519 // Declare memmove/memset for Sloaris.
520 // Rewrote fg_time.c routine to get LST start seconds to better handle
521 // Solaris, and be easier to port, and understand the GMT vs. local
524 // Revision 1.8 1998/06/05 18:18:13 curt
525 // Incorporated some automake conditionals to try to support mktime() correctly
526 // on a wider variety of platforms.
527 // Added the declaration of memmove needed by the stl which apparently
528 // solaris only defines for cc compilations and not for c++ (__STDC__)
530 // Revision 1.7 1998/05/30 01:57:25 curt
533 // Revision 1.6 1998/05/02 01:53:17 curt
534 // Fine tuning mktime() support because of varying behavior on different
537 // Revision 1.5 1998/04/28 21:45:34 curt
538 // Fixed a horible bug that cause the time to be *WAY* off when compiling
539 // with the CygWin32 compiler. This may not yet completely address other
540 // Win32 compilers, but we'll have to take them on a case by case basis.
542 // Revision 1.4 1998/04/28 01:22:16 curt
543 // Type-ified fgTIME and fgVIEW.
545 // Revision 1.3 1998/04/25 22:06:33 curt
546 // Edited cvs log messages in source files ... bad bad bad!
548 // Revision 1.2 1998/04/25 20:24:02 curt
549 // Cleaned up initialization sequence to eliminate interdependencies
550 // between sun position, lighting, and view position. This creates a
551 // valid single pass initialization path.
553 // Revision 1.1 1998/04/24 00:52:27 curt
554 // Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
556 // Separated out lighting calcs into their own file.
558 // Revision 1.41 1998/04/22 13:24:05 curt
559 // C++ - ifiing the code a bit.
560 // Starting to reorginize some of the lighting calcs to use a table lookup.
562 // Revision 1.40 1998/04/18 04:14:09 curt
563 // Moved fg_debug.c to it's own library.
565 // Revision 1.39 1998/04/09 18:40:14 curt
566 // We had unified some of the platform disparate time handling code, and
567 // there was a bug in timesum() which calculated a new time stamp based on
568 // the current time stamp + offset. This hosed the periodic event processing
569 // logic because you'd never arrive at the time the event was scheduled for.
570 // Sky updates and lighting changes are handled via this event mechanism so
571 // they never changed ... it is fixed now.
573 // Revision 1.38 1998/04/08 23:35:40 curt
574 // Tweaks to Gnu automake/autoconf system.
576 // Revision 1.37 1998/04/03 22:12:55 curt
577 // Converting to Gnu autoconf system.
578 // Centralized time handling differences.
580 // Revision 1.36 1998/03/09 22:48:09 curt
581 // Debug message tweaks.
583 // Revision 1.35 1998/02/09 15:07:52 curt
586 // Revision 1.34 1998/02/07 15:29:47 curt
587 // Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
588 // <chotchkiss@namg.us.anritsu.com>
590 // Revision 1.33 1998/02/02 20:54:04 curt
591 // Incorporated Durk's changes.
593 // Revision 1.32 1998/02/01 03:39:56 curt
596 // Revision 1.31 1998/01/27 00:48:06 curt
597 // Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
598 // system and commandline/config file processing code.
600 // Revision 1.30 1998/01/21 21:11:35 curt
603 // Revision 1.29 1998/01/19 19:27:20 curt
604 // Merged in make system changes from Bob Kuehne <rpk@sgi.com>
605 // This should simplify things tremendously.
607 // Revision 1.28 1998/01/19 18:35:49 curt
608 // Minor tweaks and fixes for cygwin32.
610 // Revision 1.27 1998/01/13 00:23:13 curt
611 // Initial changes to support loading and management of scenery tiles. Note,
612 // there's still a fair amount of work left to be done.
614 // Revision 1.26 1998/01/05 18:44:36 curt
615 // Add an option to advance/decrease time from keyboard.
617 // Revision 1.25 1997/12/31 17:46:50 curt
618 // Tweaked fg_time.c to be able to use ftime() instead of gettimeofday()
620 // Revision 1.24 1997/12/30 22:22:42 curt
621 // Further integration of event manager.
623 // Revision 1.23 1997/12/30 20:47:58 curt
624 // Integrated new event manager with subsystem initializations.
626 // Revision 1.22 1997/12/30 01:38:47 curt
627 // Switched back to per vertex normals and smooth shading for terrain.
629 // Revision 1.21 1997/12/23 04:58:39 curt
630 // Tweaked the sky coloring a bit to build in structures to allow finer rgb
633 // Revision 1.20 1997/12/15 23:55:06 curt
634 // Add xgl wrappers for debugging.
635 // Generate terrain normals on the fly.
637 // Revision 1.19 1997/12/15 20:59:10 curt
640 // Revision 1.18 1997/12/12 21:41:31 curt
641 // More light/material property tweaking ... still a ways off.
643 // Revision 1.17 1997/12/12 19:53:04 curt
644 // Working on lightling and material properties.
646 // Revision 1.16 1997/12/11 04:43:57 curt
647 // Fixed sun vector and lighting problems. I thing the moon is now lit
650 // Revision 1.15 1997/12/10 22:37:54 curt
651 // Prepended "fg" on the name of all global structures that didn't have it yet.
652 // i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
654 // Revision 1.14 1997/12/10 01:19:52 curt
655 // Tweaks for verion 0.15 release.
657 // Revision 1.13 1997/12/09 05:11:56 curt
658 // Working on tweaking lighting.
660 // Revision 1.12 1997/12/09 04:25:37 curt
661 // Working on adding a global lighting params structure.
663 // Revision 1.11 1997/11/25 19:25:40 curt
664 // Changes to integrate Durk's moon/sun code updates + clean up.
666 // Revision 1.10 1997/11/15 18:16:42 curt
669 // Revision 1.9 1997/11/14 00:26:50 curt
670 // Transform scenery coordinates earlier in pipeline when scenery is being
671 // created, not when it is being loaded. Precalculate normals for each node
672 // as average of the normals of each containing polygon so Garoude shading is
675 // Revision 1.8 1997/10/25 03:30:08 curt
678 // Revision 1.7 1997/09/23 00:29:50 curt
679 // Tweaks to get things to compile with gcc-win32.
681 // Revision 1.6 1997/09/20 03:34:34 curt
682 // Still trying to get those durned stars aligned properly.
684 // Revision 1.5 1997/09/16 22:14:52 curt
685 // Tweaked time of day lighting equations. Don't draw stars during the day.
687 // Revision 1.4 1997/09/16 15:50:31 curt
688 // Working on star alignment and time issues.
690 // Revision 1.3 1997/09/13 02:00:08 curt
691 // Mostly working on stars and generating sidereal time for accurate star
694 // Revision 1.2 1997/08/27 03:30:35 curt
695 // Changed naming scheme of basic shared structures.
697 // Revision 1.1 1997/08/13 21:55:59 curt