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)
30 #include "Include/compiler.h"
32 #ifdef FG_HAVE_STD_INCLUDES
44 #ifdef HAVE_SYS_TIMEB_H
45 # include <sys/timeb.h> // for ftime() and struct timeb
48 # include <unistd.h> // for gettimeofday()
50 #ifdef HAVE_SYS_TIME_H
51 # include <sys/time.h> // for get/setitimer, gettimeofday, struct timeval
54 #include <Astro/sky.hxx>
55 #include <Astro/solarsystem.hxx>
56 #include <Debug/logstream.hxx>
57 #include <FDM/flight.hxx>
58 #include <Include/fg_constants.h>
59 #include <Main/options.hxx>
60 #include <Time/light.hxx>
62 #include "fg_time.hxx"
65 #define DEGHR(x) ((x)/15.)
66 #define RADHR(x) DEGHR(x*RAD_TO_DEG)
68 // #define MK_TIME_IS_GMT 0 // default value
69 // #define TIME_ZONE_OFFSET_WORK 0 // default value
72 fgTIME cur_time_params;
75 // Force an update of the sky and lighting parameters
76 static void local_update_sky_and_lighting_params( void ) {
78 SolarSystem::theSolarSystem->rebuild();
79 cur_light_params.Update();
84 // Initialize the time dependent variables
85 void fgTimeInit(fgTIME *t) {
86 FG_LOG( FG_EVENT, FG_INFO, "Initializing Time" );
88 t->gst_diff = -9999.0;
90 FG_LOG( FG_EVENT, FG_DEBUG,
91 "time offset = " << current_options.get_time_offset() );
93 t->warp = current_options.get_time_offset();
96 t->pause = current_options.get_pause();
100 // given a date in months, mn, days, dy, years, yr, return the
101 // modified Julian date (number of days elapsed since 1900 jan 0.5),
102 // mjd. Adapted from Xephem.
104 double cal_mjd (int mn, double dy, int yr) {
105 static double last_mjd, last_dy;
107 static int last_mn, last_yr;
111 if (mn == last_mn && yr == last_yr && dy == last_dy) {
117 y = (yr < 0) ? yr + 1 : yr;
123 if (yr < 1582 || (yr == 1582 && (mn < 10 || (mn == 10 && dy < 15)))) {
132 c = (long)((365.25*y) - 0.75) - 694025L;
134 c = (long)(365.25*y) - 694025L;
137 d = (int)(30.6001*(m+1));
139 mjd = b + c + d + dy - 0.5;
150 // given an mjd, return greenwich mean sidereal time, gst
152 double utc_gst (double mjd) {
154 double day = floor(mjd-0.5)+0.5;
155 double hr = (mjd-day)*24.0;
158 T = ((int)(mjd - 0.5) + 0.5 - J2000)/36525.0;
159 x = 24110.54841 + (8640184.812866 + (0.093104 - 6.2e-6 * T) * T) * T;
161 gst = (1.0/SIDRATE)*hr + x;
163 FG_LOG( FG_EVENT, FG_DEBUG, " gst => " << gst );
169 // given Julian Date and Longitude (decimal degrees West) compute and
170 // return Local Sidereal Time, in decimal hours.
172 // Provided courtesy of ecdowney@noao.edu (Elwood Downey)
175 double sidereal_precise (double mjd, double lng) {
179 /* printf ("Current Lst on JD %13.5f at %8.4f degrees West: ",
182 // convert to required internal units
185 // compute LST and print
187 lst = gst - RADHR (lng);
188 lst -= 24.0*floor(lst/24.0);
189 // printf ("%7.4f\n", lst);
196 // Fix up timezone if using ftime()
197 long int fix_up_timezone( long int timezone_orig ) {
198 #if !defined( HAVE_GETTIMEOFDAY ) && defined( HAVE_FTIME )
199 // ftime() needs a little extra help finding the current timezone
200 struct timeb current;
202 return( current.timezone * 60 );
204 return( timezone_orig );
209 // Return time_t for Sat Mar 21 12:00:00 GMT
211 // I believe the mktime() has a SYSV vs. BSD behavior difference.
213 // The BSD style mktime() is nice because it returns its result
214 // assuming you have specified the input time in GMT
216 // The SYSV style mktime() is a pain because it returns its result
217 // assuming you have specified the input time in your local timezone.
218 // Therefore you have to go to extra trouble to convert back to GMT.
220 // If you are having problems with incorrectly positioned astronomical
221 // bodies, this is a really good place to start looking.
223 time_t get_start_gmt(int year) {
226 // For now we assume that if daylight is not defined in
227 // /usr/include/time.h that we have a machine with a BSD behaving
229 # if !defined(HAVE_DAYLIGHT)
230 # define MK_TIME_IS_GMT 1
233 // timezone seems to work as a proper offset for Linux & Solaris
234 # if defined( __linux__ ) || defined( __sun__ )
235 # define TIMEZONE_OFFSET_WORKS 1
244 mt.tm_isdst = -1; // let the system determine the proper time zone
246 # if defined( MK_TIME_IS_GMT )
247 return ( mktime(&mt) );
248 # else // ! defined ( MK_TIME_IS_GMT )
250 long int start = mktime(&mt);
252 FG_LOG( FG_EVENT, FG_DEBUG, "start1 = " << start );
253 // the ctime() call can screw up time progression on some versions
255 // fgPrintf( FG_EVENT, FG_DEBUG, "start2 = %s", ctime(&start));
256 FG_LOG( FG_EVENT, FG_DEBUG, "(tm_isdst = " << mt.tm_isdst << ")" );
258 timezone = fix_up_timezone( timezone );
260 # if defined( TIMEZONE_OFFSET_WORKS )
261 FG_LOG( FG_EVENT, FG_DEBUG,
262 "start = " << start << ", timezone = " << timezone );
263 return( start - timezone );
264 # else // ! defined( TIMEZONE_OFFSET_WORKS )
266 daylight = mt.tm_isdst;
267 if ( daylight > 0 ) {
269 } else if ( daylight < 0 ) {
270 FG_LOG( FG_EVENT, FG_WARN,
271 "OOOPS, problem in fg_time.cxx, no daylight savings info." );
274 long int offset = -(timezone / 3600 - daylight);
276 FG_LOG( FG_EVENT, FG_DEBUG, " Raw time zone offset = " << timezone );
277 FG_LOG( FG_EVENT, FG_DEBUG, " Daylight Savings = " << daylight );
278 FG_LOG( FG_EVENT, FG_DEBUG, " Local hours from GMT = " << offset );
280 long int start_gmt = start - timezone + (daylight * 3600);
282 FG_LOG( FG_EVENT, FG_DEBUG, " March 21 noon (CST) = " << start );
284 return ( start_gmt );
285 # endif // ! defined( TIMEZONE_OFFSET_WORKS )
286 # endif // ! defined ( MK_TIME_IS_GMT )
290 format_time( const struct tm* p, char* buf )
292 sprintf( buf, "%d/%d/%2d %d:%02d:%02d",
293 p->tm_mon, p->tm_mday, p->tm_year,
294 p->tm_hour, p->tm_min, p->tm_sec);
298 // return a courser but cheaper estimate of sidereal time
299 double sidereal_course(fgTIME *t, double lng) {
301 time_t start_gmt, now;
302 double diff, part, days, hours, lst;
307 start_gmt = get_start_gmt(gmt->tm_year);
309 FG_LOG( FG_EVENT, FG_DEBUG, " COURSE: GMT = " << format_time(gmt, tbuf) );
310 FG_LOG( FG_EVENT, FG_DEBUG, " March 21 noon (GMT) = " << start_gmt );
312 diff = (now - start_gmt) / (3600.0 * 24.0);
314 FG_LOG( FG_EVENT, FG_DEBUG,
315 " Time since 3/21/" << gmt->tm_year << " GMT = " << diff );
317 part = fmod(diff, 1.0);
319 hours = gmt->tm_hour + gmt->tm_min/60.0 + gmt->tm_sec/3600.0;
321 lst = (days - lng)/15.0 + hours - 12;
323 while ( lst < 0.0 ) {
327 FG_LOG( FG_EVENT, FG_DEBUG,
328 " days = " << days << " hours = " << hours << " lon = "
329 << lng << " lst = " << lst );
335 // Update time variables such as gmt, julian date, and sidereal time
336 void fgTimeUpdate(FGInterface *f, fgTIME *t) {
337 double gst_precise, gst_course;
339 FG_LOG( FG_EVENT, FG_DEBUG, "Updating time" );
341 // get current Unix calendar time (in seconds)
342 t->warp += t->warp_delta;
343 t->cur_time = time(NULL) + t->warp;
344 FG_LOG( FG_EVENT, FG_DEBUG,
345 " Current Unix calendar time = " << t->cur_time
346 << " warp = " << t->warp << " delta = " << t->warp_delta );
348 if ( t->warp_delta ) {
349 // time is changing so force an update
350 local_update_sky_and_lighting_params();
353 // get GMT break down for current time
354 t->gmt = gmtime(&t->cur_time);
355 FG_LOG( FG_EVENT, FG_DEBUG,
356 " Current GMT = " << t->gmt->tm_mon+1 << "/"
357 << t->gmt->tm_mday << "/" << t->gmt->tm_year << " "
358 << t->gmt->tm_hour << ":" << t->gmt->tm_min << ":"
361 // calculate modified Julian date
362 t->mjd = cal_mjd ((int)(t->gmt->tm_mon+1), (double)t->gmt->tm_mday,
363 (int)(t->gmt->tm_year + 1900));
365 // add in partial day
366 t->mjd += (t->gmt->tm_hour / 24.0) + (t->gmt->tm_min / (24.0 * 60.0)) +
367 (t->gmt->tm_sec / (24.0 * 60.0 * 60.0));
369 // convert "back" to Julian date + partial day (as a fraction of one)
370 t->jd = t->mjd + MJD0;
371 FG_LOG( FG_EVENT, FG_DEBUG, " Current Julian Date = " << t->jd );
373 // printf(" Current Longitude = %.3f\n", FG_Longitude * RAD_TO_DEG);
375 // Calculate local side real time
376 if ( t->gst_diff < -100.0 ) {
377 // first time through do the expensive calculation & cheap
378 // calculation to get the difference.
379 FG_LOG( FG_EVENT, FG_INFO, " First time, doing precise gst" );
380 t->gst = gst_precise = sidereal_precise(t->mjd, 0.00);
381 gst_course = sidereal_course(t, 0.00);
382 t->gst_diff = gst_precise - gst_course;
385 sidereal_course(t, -(f->get_Longitude() * RAD_TO_DEG)) + t->gst_diff;
387 // course + difference should drift off very slowly
388 t->gst = sidereal_course(t, 0.00) + t->gst_diff;
389 t->lst = sidereal_course(t, -(f->get_Longitude() * RAD_TO_DEG)) +
392 FG_LOG( FG_EVENT, FG_DEBUG,
393 " Current lon=0.00 Sidereal Time = " << t->gst );
394 FG_LOG( FG_EVENT, FG_DEBUG,
395 " Current LOCAL Sidereal Time = " << t->lst << " ("
396 << sidereal_precise(t->mjd, -(f->get_Longitude() * RAD_TO_DEG))
397 << ") (diff = " << t->gst_diff << ")" );
402 // Revision 1.31 1999/02/05 21:29:18 curt
403 // Modifications to incorporate Jon S. Berndts flight model code.
405 // Revision 1.30 1999/02/01 21:33:37 curt
406 // Renamed FlightGear/Simulator/Flight to FlightGear/Simulator/FDM since
407 // Jon accepted my offer to do this and thought it was a good idea.
409 // Revision 1.29 1999/01/19 20:57:08 curt
410 // MacOS portability changes contributed by "Robert Puyol" <puyol@abvent.fr>
412 // Revision 1.28 1999/01/07 20:25:34 curt
413 // Portability changes and updates from Bernie Bright.
415 // Revision 1.27 1998/12/11 20:26:55 curt
418 // Revision 1.26 1998/12/05 15:54:28 curt
419 // Renamed class fgFLIGHT to class FGState as per request by JSB.
421 // Revision 1.25 1998/12/05 14:21:30 curt
422 // Moved struct fg_timestamp to class fgTIMESTAMP and moved it's definition
423 // to it's own file, timestamp.hxx.
425 // Revision 1.24 1998/12/04 01:32:49 curt
426 // Converted "struct fg_timestamp" to "class fgTIMESTAMP" and added some
427 // convenience inline operators.
429 // Revision 1.23 1998/12/03 01:18:40 curt
430 // Converted fgFLIGHT to a class.
432 // Revision 1.22 1998/11/16 14:00:28 curt
433 // FG_LOG() message tweaks.
435 // Revision 1.21 1998/11/06 21:18:26 curt
436 // Converted to new logstream debugging facility. This allows release
437 // builds with no messages at all (and no performance impact) by using
438 // the -DFG_NDEBUG flag.
440 // Revision 1.20 1998/11/02 18:25:38 curt
441 // Check for __CYGWIN__ (b20) as well as __CYGWIN32__ (pre b20 compilers)
442 // Other misc. tweaks.
444 // Revision 1.19 1998/10/17 01:34:29 curt
447 // Revision 1.18 1998/10/02 21:36:09 curt
448 // Fixes to try to break through the win95/98 18.3 fps barrier.
450 // Revision 1.17 1998/09/15 04:27:49 curt
451 // Changes for new astro code.
453 // Revision 1.16 1998/08/29 13:11:32 curt
454 // Bernie Bright writes:
455 // I've created some new classes to enable pointers-to-functions and
456 // pointers-to-class-methods to be treated like objects. These objects
457 // can be registered with fgEVENT_MGR.
459 // File "Include/fg_callback.hxx" contains the callback class defns.
461 // Modified fgEVENT and fgEVENT_MGR to use the callback classes. Also
462 // some minor tweaks to STL usage.
464 // Added file "Include/fg_stl_config.h" to deal with STL portability
465 // issues. I've added an initial config for egcs (and probably gcc-2.8.x).
466 // I don't have access to Visual C++ so I've left that for someone else.
467 // This file is influenced by the stl_config.h file delivered with egcs.
469 // Added "Include/auto_ptr.hxx" which contains an implementation of the
470 // STL auto_ptr class which is not provided in all STL implementations
471 // and is needed to use the callback classes.
473 // Deleted fgLightUpdate() which was just a wrapper to call
474 // fgLIGHT::Update().
476 // Modified fg_init.cxx to register two method callbacks in place of the
477 // old wrapper functions.
479 // Revision 1.15 1998/08/24 20:12:16 curt
480 // Rewrote sidereal_course with simpler parameters.
482 // Revision 1.14 1998/08/05 00:20:07 curt
483 // Added a local routine to update lighting params every frame when time is
486 // Revision 1.13 1998/07/30 23:48:55 curt
490 // Revision 1.12 1998/07/27 18:42:22 curt
491 // Added a pause option.
493 // Revision 1.11 1998/07/22 21:45:37 curt
494 // fg_time.cxx: Removed call to ctime() in a printf() which should be harmless
495 // but seems to be triggering a bug.
496 // light.cxx: Added code to adjust fog color based on sunrise/sunset effects
497 // and view orientation. This is an attempt to match the fog color to the
498 // sky color in the center of the screen. You see discrepancies at the
499 // edges, but what else can be done?
500 // sunpos.cxx: Caculate local direction to sun here. (what compass direction
501 // do we need to face to point directly at sun)
503 // Revision 1.10 1998/07/13 21:02:07 curt
504 // Wrote access functions for current fgOPTIONS.
506 // Revision 1.9 1998/06/12 00:59:53 curt
507 // Build only static libraries.
508 // Declare memmove/memset for Sloaris.
509 // Rewrote fg_time.c routine to get LST start seconds to better handle
510 // Solaris, and be easier to port, and understand the GMT vs. local
513 // Revision 1.8 1998/06/05 18:18:13 curt
514 // Incorporated some automake conditionals to try to support mktime() correctly
515 // on a wider variety of platforms.
516 // Added the declaration of memmove needed by the stl which apparently
517 // solaris only defines for cc compilations and not for c++ (__STDC__)
519 // Revision 1.7 1998/05/30 01:57:25 curt
522 // Revision 1.6 1998/05/02 01:53:17 curt
523 // Fine tuning mktime() support because of varying behavior on different
526 // Revision 1.5 1998/04/28 21:45:34 curt
527 // Fixed a horible bug that cause the time to be *WAY* off when compiling
528 // with the CygWin32 compiler. This may not yet completely address other
529 // Win32 compilers, but we'll have to take them on a case by case basis.
531 // Revision 1.4 1998/04/28 01:22:16 curt
532 // Type-ified fgTIME and fgVIEW.
534 // Revision 1.3 1998/04/25 22:06:33 curt
535 // Edited cvs log messages in source files ... bad bad bad!
537 // Revision 1.2 1998/04/25 20:24:02 curt
538 // Cleaned up initialization sequence to eliminate interdependencies
539 // between sun position, lighting, and view position. This creates a
540 // valid single pass initialization path.
542 // Revision 1.1 1998/04/24 00:52:27 curt
543 // Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
545 // Separated out lighting calcs into their own file.
547 // Revision 1.41 1998/04/22 13:24:05 curt
548 // C++ - ifiing the code a bit.
549 // Starting to reorginize some of the lighting calcs to use a table lookup.
551 // Revision 1.40 1998/04/18 04:14:09 curt
552 // Moved fg_debug.c to it's own library.
554 // Revision 1.39 1998/04/09 18:40:14 curt
555 // We had unified some of the platform disparate time handling code, and
556 // there was a bug in timesum() which calculated a new time stamp based on
557 // the current time stamp + offset. This hosed the periodic event processing
558 // logic because you'd never arrive at the time the event was scheduled for.
559 // Sky updates and lighting changes are handled via this event mechanism so
560 // they never changed ... it is fixed now.
562 // Revision 1.38 1998/04/08 23:35:40 curt
563 // Tweaks to Gnu automake/autoconf system.
565 // Revision 1.37 1998/04/03 22:12:55 curt
566 // Converting to Gnu autoconf system.
567 // Centralized time handling differences.
569 // Revision 1.36 1998/03/09 22:48:09 curt
570 // Debug message tweaks.
572 // Revision 1.35 1998/02/09 15:07:52 curt
575 // Revision 1.34 1998/02/07 15:29:47 curt
576 // Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
577 // <chotchkiss@namg.us.anritsu.com>
579 // Revision 1.33 1998/02/02 20:54:04 curt
580 // Incorporated Durk's changes.
582 // Revision 1.32 1998/02/01 03:39:56 curt
585 // Revision 1.31 1998/01/27 00:48:06 curt
586 // Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
587 // system and commandline/config file processing code.
589 // Revision 1.30 1998/01/21 21:11:35 curt
592 // Revision 1.29 1998/01/19 19:27:20 curt
593 // Merged in make system changes from Bob Kuehne <rpk@sgi.com>
594 // This should simplify things tremendously.
596 // Revision 1.28 1998/01/19 18:35:49 curt
597 // Minor tweaks and fixes for cygwin32.
599 // Revision 1.27 1998/01/13 00:23:13 curt
600 // Initial changes to support loading and management of scenery tiles. Note,
601 // there's still a fair amount of work left to be done.
603 // Revision 1.26 1998/01/05 18:44:36 curt
604 // Add an option to advance/decrease time from keyboard.
606 // Revision 1.25 1997/12/31 17:46:50 curt
607 // Tweaked fg_time.c to be able to use ftime() instead of gettimeofday()
609 // Revision 1.24 1997/12/30 22:22:42 curt
610 // Further integration of event manager.
612 // Revision 1.23 1997/12/30 20:47:58 curt
613 // Integrated new event manager with subsystem initializations.
615 // Revision 1.22 1997/12/30 01:38:47 curt
616 // Switched back to per vertex normals and smooth shading for terrain.
618 // Revision 1.21 1997/12/23 04:58:39 curt
619 // Tweaked the sky coloring a bit to build in structures to allow finer rgb
622 // Revision 1.20 1997/12/15 23:55:06 curt
623 // Add xgl wrappers for debugging.
624 // Generate terrain normals on the fly.
626 // Revision 1.19 1997/12/15 20:59:10 curt
629 // Revision 1.18 1997/12/12 21:41:31 curt
630 // More light/material property tweaking ... still a ways off.
632 // Revision 1.17 1997/12/12 19:53:04 curt
633 // Working on lightling and material properties.
635 // Revision 1.16 1997/12/11 04:43:57 curt
636 // Fixed sun vector and lighting problems. I thing the moon is now lit
639 // Revision 1.15 1997/12/10 22:37:54 curt
640 // Prepended "fg" on the name of all global structures that didn't have it yet.
641 // i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
643 // Revision 1.14 1997/12/10 01:19:52 curt
644 // Tweaks for verion 0.15 release.
646 // Revision 1.13 1997/12/09 05:11:56 curt
647 // Working on tweaking lighting.
649 // Revision 1.12 1997/12/09 04:25:37 curt
650 // Working on adding a global lighting params structure.
652 // Revision 1.11 1997/11/25 19:25:40 curt
653 // Changes to integrate Durk's moon/sun code updates + clean up.
655 // Revision 1.10 1997/11/15 18:16:42 curt
658 // Revision 1.9 1997/11/14 00:26:50 curt
659 // Transform scenery coordinates earlier in pipeline when scenery is being
660 // created, not when it is being loaded. Precalculate normals for each node
661 // as average of the normals of each containing polygon so Garoude shading is
664 // Revision 1.8 1997/10/25 03:30:08 curt
667 // Revision 1.7 1997/09/23 00:29:50 curt
668 // Tweaks to get things to compile with gcc-win32.
670 // Revision 1.6 1997/09/20 03:34:34 curt
671 // Still trying to get those durned stars aligned properly.
673 // Revision 1.5 1997/09/16 22:14:52 curt
674 // Tweaked time of day lighting equations. Don't draw stars during the day.
676 // Revision 1.4 1997/09/16 15:50:31 curt
677 // Working on star alignment and time issues.
679 // Revision 1.3 1997/09/13 02:00:08 curt
680 // Mostly working on stars and generating sidereal time for accurate star
683 // Revision 1.2 1997/08/27 03:30:35 curt
684 // Changed naming scheme of basic shared structures.
686 // Revision 1.1 1997/08/13 21:55:59 curt