**************************************************************************/
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#ifdef WIN32
+#include <sys/time.h> /* for gettimeofday() */
+#include <unistd.h> /* for gettimeofday() */
+#endif
+
#include "fg_time.h"
+#include "../constants.h"
+#include "../Flight/flight.h"
+#include "../Time/fg_time.h"
+
+
+#define DEGHR(x) ((x)/15.)
+#define RADHR(x) DEGHR(x*RAD_TO_DEG)
struct fgTIME cur_time_params;
+struct fgLIGHT cur_light_params;
+
+
+/* Initialize the time dependent variables */
+
+void fgTimeInit(struct fgTIME *t) {
+ t->gst_diff = -9999.0;
+}
+
+
+/* given a date in months, mn, days, dy, years, yr, return the
+ * modified Julian date (number of days elapsed since 1900 jan 0.5),
+ * mjd. Adapted from Xephem. */
+
+double cal_mjd (int mn, double dy, int yr) {
+ static double last_mjd, last_dy;
+ double mjd;
+ static int last_mn, last_yr;
+ int b, d, m, y;
+ long c;
+
+ if (mn == last_mn && yr == last_yr && dy == last_dy) {
+ mjd = last_mjd;
+ return(mjd);
+ }
+
+ m = mn;
+ y = (yr < 0) ? yr + 1 : yr;
+ if (mn < 3) {
+ m += 12;
+ y -= 1;
+ }
+
+ if (yr < 1582 || (yr == 1582 && (mn < 10 || (mn == 10 && dy < 15)))) {
+ b = 0;
+ } else {
+ int a;
+ a = y/100;
+ b = 2 - a + a/4;
+ }
+
+ if (y < 0) {
+ c = (long)((365.25*y) - 0.75) - 694025L;
+ } else {
+ c = (long)(365.25*y) - 694025L;
+ }
+
+ d = 30.6001*(m+1);
+
+ mjd = b + c + d + dy - 0.5;
+
+ last_mn = mn;
+ last_dy = dy;
+ last_yr = yr;
+ last_mjd = mjd;
+
+ return(mjd);
+}
+
+
+/* given an mjd, return greenwich mean siderial time, gst */
+
+double utc_gst (double mjd) {
+ double gst;
+ double day = floor(mjd-0.5)+0.5;
+ double hr = (mjd-day)*24.0;
+ double T, x;
+
+ T = ((int)(mjd - 0.5) + 0.5 - J2000)/36525.0;
+ x = 24110.54841 + (8640184.812866 + (0.093104 - 6.2e-6 * T) * T) * T;
+ x /= 3600.0;
+ gst = (1.0/SIDRATE)*hr + x;
+
+ printf("gst => %.4f\n", gst);
+
+ return(gst);
+}
+
+
+/* given Julian Date and Longitude (decimal degrees West) compute and
+ * return Local Sidereal Time, in decimal hours.
+ *
+ * Provided courtesy of ecdowney@noao.edu (Elwood Downey)
+ */
+
+double sidereal_precise (double mjd, double lng) {
+ double gst;
+ double lst;
+
+ /* printf ("Current Lst on JD %13.5f at %8.4f degrees West: ",
+ mjd + MJD0, lng); */
+
+ /* convert to required internal units */
+ lng *= DEG_TO_RAD;
+
+ /* compute LST and print */
+ gst = utc_gst (mjd);
+ lst = gst - RADHR (lng);
+ lst -= 24.0*floor(lst/24.0);
+ /* printf ("%7.4f\n", lst); */
+
+ /* that's all */
+ return (lst);
+}
+
+
+/* return a courser but cheaper estimate of sidereal time */
+double sidereal_course(struct tm *gmt, time_t now, double lng) {
+ time_t start, start_gmt;
+ struct tm mt;
+ long int offset;
+ double diff, part, days, hours, lst;
+
+#ifdef WIN32
+ int daylight;
+ long int timezone;
+
+ struct timeval tv;
+ struct timezone tz;
+#endif
+
+ printf("COURSE: GMT = %d/%d/%2d %d:%02d:%02d\n",
+ gmt->tm_mon, gmt->tm_mday, gmt->tm_year,
+ gmt->tm_hour, gmt->tm_min, gmt->tm_sec);
+
+ mt.tm_mon = 2;
+ mt.tm_mday = 21;
+ mt.tm_year = gmt->tm_year;
+ mt.tm_hour = 12;
+ mt.tm_min = 0;
+ mt.tm_sec = 0;
+
+ start = mktime(&mt);
+
+#ifdef WIN32
+ daylight = mt.tm_isdst;
+ gettimeofday(&tv, &tz);
+ timezone = tz.tz_minuteswest * 60;
+#endif
+
+ if ( daylight > 0 ) {
+ daylight = 1;
+ } else if ( daylight < 0 ) {
+ printf("OOOPS, big time problem in fg_time.c, no daylight savings info.\n");
+ }
+
+ offset = -(timezone / 3600 - daylight);
+
+ printf("Raw time zone offset = %ld\n", timezone);
+ printf("Daylight Savings = %d\n", daylight);
+
+ printf("Local hours from GMT = %ld\n", offset);
+
+ start_gmt = start - timezone + (daylight * 3600);
+
+ printf("March 21 noon (CST) = %ld\n", start);
+ printf("March 21 noon (GMT) = %ld\n", start_gmt);
+
+ diff = (now - start_gmt) / (3600.0 * 24.0);
+
+ printf("Time since 3/21/%2d GMT = %.2f\n", gmt->tm_year, diff);
+
+ part = fmod(diff, 1.0);
+ days = diff - part;
+ hours = gmt->tm_hour + gmt->tm_min/60.0 + gmt->tm_sec/3600.0;
+
+ lst = (days - lng)/15.0 + hours - 12;
+
+ while ( lst < 0.0 ) {
+ lst += 24.0;
+ }
+
+ printf("days = %.1f hours = %.2f lon = %.2f lst = %.2f\n",
+ days, hours, lng, lst);
+
+ return(lst);
+}
+
+
+/* Update the time dependent variables */
+
+void fgTimeUpdate(struct fgFLIGHT *f, struct fgTIME *t) {
+ double gst_precise, gst_course;
+ static long int warp = 0;
+
+ /* get current Unix calendar time (in seconds) */
+ warp += 60;
+ /* warp = 0; */
+ t->cur_time = time(NULL) + (0) * 60 * 60;
+ t->cur_time += warp;
+ printf("Current Unix calendar time = %ld warp = %ld\n", t->cur_time, warp);
+
+ /* get GMT break down for current time */
+ t->gmt = gmtime(&t->cur_time);
+ printf("Current GMT = %d/%d/%2d %d:%02d:%02d\n",
+ t->gmt->tm_mon+1, t->gmt->tm_mday, t->gmt->tm_year,
+ t->gmt->tm_hour, t->gmt->tm_min, t->gmt->tm_sec);
+
+ /* calculate modified Julian date */
+ t->mjd = cal_mjd ((int)(t->gmt->tm_mon+1), (double)t->gmt->tm_mday,
+ (int)(t->gmt->tm_year + 1900));
+
+ /* add in partial day */
+ t->mjd += (t->gmt->tm_hour / 24.0) + (t->gmt->tm_min / (24.0 * 60.0)) +
+ (t->gmt->tm_sec / (24.0 * 60.0 * 60.0));
+
+ /* convert "back" to Julian date + partial day (as a fraction of one) */
+ t->jd = t->mjd + MJD0;
+ printf("Current Julian Date = %.5f\n", t->jd);
+
+ printf("Current Longitude = %.3f\n", FG_Longitude * RAD_TO_DEG);
+
+ /* Calculate local side real time */
+ if ( t->gst_diff < -100.0 ) {
+ /* first time through do the expensive calculation & cheap
+ calculation to get the difference. */
+ printf("First time, doing precise gst\n");
+ t->gst = gst_precise = sidereal_precise(t->mjd, 0.00);
+ gst_course = sidereal_course(t->gmt, t->cur_time, 0.00);
+ t->gst_diff = gst_precise - gst_course;
+
+ t->lst =
+ sidereal_course(t->gmt, t->cur_time, -(FG_Longitude * RAD_TO_DEG))
+ + t->gst_diff;
+ } else {
+ /* course + difference should drift off very slowly */
+ t->gst =
+ sidereal_course(t->gmt, t->cur_time, 0.00) + t->gst_diff;
+ t->lst =
+ sidereal_course(t->gmt, t->cur_time, -(FG_Longitude * RAD_TO_DEG))
+ + t->gst_diff;
+ }
+ /* printf("Current lon=0.00 Sidereal Time = %.3f\n", t->gst); */
+ /* printf("Current LOCAL Sidereal Time = %.3f (%.3f) (diff = %.3f)\n",
+ t->lst, sidereal_precise(t->mjd, -(FG_Longitude * RAD_TO_DEG)),
+ t->gst_diff); */
+}
/* $Log$
-/* Revision 1.2 1997/08/27 03:30:35 curt
-/* Changed naming scheme of basic shared structures.
+/* Revision 1.15 1997/12/10 22:37:54 curt
+/* Prepended "fg" on the name of all global structures that didn't have it yet.
+/* i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
/*
+ * Revision 1.14 1997/12/10 01:19:52 curt
+ * Tweaks for verion 0.15 release.
+ *
+ * Revision 1.13 1997/12/09 05:11:56 curt
+ * Working on tweaking lighting.
+ *
+ * Revision 1.12 1997/12/09 04:25:37 curt
+ * Working on adding a global lighting params structure.
+ *
+ * Revision 1.11 1997/11/25 19:25:40 curt
+ * Changes to integrate Durk's moon/sun code updates + clean up.
+ *
+ * Revision 1.10 1997/11/15 18:16:42 curt
+ * minor tweaks.
+ *
+ * Revision 1.9 1997/11/14 00:26:50 curt
+ * Transform scenery coordinates earlier in pipeline when scenery is being
+ * created, not when it is being loaded. Precalculate normals for each node
+ * as average of the normals of each containing polygon so Garoude shading is
+ * now supportable.
+ *
+ * Revision 1.8 1997/10/25 03:30:08 curt
+ * Misc. tweaks.
+ *
+ * Revision 1.7 1997/09/23 00:29:50 curt
+ * Tweaks to get things to compile with gcc-win32.
+ *
+ * Revision 1.6 1997/09/20 03:34:34 curt
+ * Still trying to get those durned stars aligned properly.
+ *
+ * Revision 1.5 1997/09/16 22:14:52 curt
+ * Tweaked time of day lighting equations. Don't draw stars during the day.
+ *
+ * Revision 1.4 1997/09/16 15:50:31 curt
+ * Working on star alignment and time issues.
+ *
+ * Revision 1.3 1997/09/13 02:00:08 curt
+ * Mostly working on stars and generating sidereal time for accurate star
+ * placement.
+ *
+ * Revision 1.2 1997/08/27 03:30:35 curt
+ * Changed naming scheme of basic shared structures.
+ *
* Revision 1.1 1997/08/13 21:55:59 curt
* Initial revision.
*
projects / flightgear.git / blobdiff