-// sunpos.c (taken from XEarth)
+// sunpos.cxx (adapted from XEarth)
// kirk johnson
// july 1993
//
// with your calculator, third edition_, peter duffett-smith,
// cambridge university press, 1988.)
//
-// RCS $Id$
-//
// Copyright (C) 1989, 1990, 1993, 1994, 1995 Kirk Lauritz Johnson
//
// Parts of the source code (as marked) are:
# include <config.h>
#endif
-#include <math.h>
-#include <stdio.h>
-#include <time.h>
+#include <Include/compiler.h>
+
+#ifdef FG_HAVE_STD_INCLUDES
+# include <cmath>
+# include <cstdio>
+# include <ctime>
+#else
+# include <math.h>
+# include <stdio.h>
+# include <time.h>
+#endif
-#include <Astro/orbits.hxx>
+#include <Debug/logstream.hxx>
+#include <Astro/solarsystem.hxx>
#include <Include/fg_constants.h>
#include <Main/views.hxx>
-#include <Math/fg_geodesy.h>
+#include <Math/fg_geodesy.hxx>
#include <Math/mat3.h>
-#include <Math/polar.h>
-#include <Math/vector.h>
-#include <Scenery/scenery.h>
+#include <Math/point3d.hxx>
+#include <Math/polar3d.hxx>
+#include <Math/vector.hxx>
+#include <Scenery/scenery.hxx>
#include "fg_time.hxx"
#include "sunpos.hxx"
+extern SolarSystem *solarSystem;
#undef E
-
-
-/*
- * the epoch upon which these astronomical calculations are based is
- * 1990 january 0.0, 631065600 seconds since the beginning of the
- * "unix epoch" (00:00:00 GMT, Jan. 1, 1970)
- *
- * given a number of seconds since the start of the unix epoch,
- * DaysSinceEpoch() computes the number of days since the start of the
- * astronomical epoch (1990 january 0.0)
- */
-
-#define EpochStart (631065600)
-#define DaysSinceEpoch(secs) (((secs)-EpochStart)*(1.0/(24*3600)))
-
-/*
- * assuming the apparent orbit of the sun about the earth is circular,
- * the rate at which the orbit progresses is given by RadsPerDay --
- * FG_2PI radians per orbit divided by 365.242191 days per year:
- */
-
-#define RadsPerDay (FG_2PI/365.242191)
-
-/*
- * details of sun's apparent orbit at epoch 1990.0 (after
- * duffett-smith, table 6, section 46)
- *
- * Epsilon_g (ecliptic longitude at epoch 1990.0) 279.403303 degrees
- * OmegaBar_g (ecliptic longitude of perigee) 282.768422 degrees
- * Eccentricity (eccentricity of orbit) 0.016713
- */
-
-#define Epsilon_g (279.403303*(FG_2PI/360))
-#define OmegaBar_g (282.768422*(FG_2PI/360))
-#define Eccentricity (0.016713)
-
-/*
- * MeanObliquity gives the mean obliquity of the earth's axis at epoch
- * 1990.0 (computed as 23.440592 degrees according to the method given
- * in duffett-smith, section 27)
- */
#define MeanObliquity (23.440592*(FG_2PI/360))
-/* static double solve_keplers_equation(double); */
-/* static double sun_ecliptic_longitude(time_t); */
static void ecliptic_to_equatorial(double, double, double *, double *);
static double julian_date(int, int, int);
static double GST(time_t);
-/*
- * solve Kepler's equation via Newton's method
- * (after duffett-smith, section 47)
- */
-/*
-static double solve_keplers_equation(double M) {
- double E;
- double delta;
-
- E = M;
- while (1) {
- delta = E - Eccentricity*sin(E) - M;
- if (fabs(delta) <= 1e-10) break;
- E -= delta / (1 - Eccentricity*cos(E));
- }
-
- return E;
-}
-*/
-
-
-/* compute ecliptic longitude of sun (in radians) (after
- * duffett-smith, section 47) */
-/*
-static double sun_ecliptic_longitude(time_t ssue) {
- // time_t ssue; // seconds since unix epoch
- double D, N;
- double M_sun, E;
- double v;
-
- D = DaysSinceEpoch(ssue);
-
- N = RadsPerDay * D;
- N = fmod(N, FG_2PI);
- if (N < 0) N += FG_2PI;
-
- M_sun = N + Epsilon_g - OmegaBar_g;
- if (M_sun < 0) M_sun += FG_2PI;
-
- E = solve_keplers_equation(M_sun);
- v = 2 * atan(sqrt((1+Eccentricity)/(1-Eccentricity)) * tan(E/2));
-
- return (v + OmegaBar_g);
-}
-*/
-
-
-/* convert from ecliptic to equatorial coordinates (after
- * duffett-smith, section 27) */
-
static void ecliptic_to_equatorial(double lambda, double beta,
double *alpha, double *delta) {
/* double lambda; ecliptic longitude */
/* double *delta; (return) declination */
double sin_e, cos_e;
+ double sin_l, cos_l;
sin_e = sin(MeanObliquity);
cos_e = cos(MeanObliquity);
+ sin_l = sin(lambda);
+ cos_l = cos(lambda);
- *alpha = atan2(sin(lambda)*cos_e - tan(beta)*sin_e, cos(lambda));
- *delta = asin(sin(beta)*cos_e + cos(beta)*sin_e*sin(lambda));
+ *alpha = atan2(sin_l*cos_e - tan(beta)*sin_e, cos_l);
+ *delta = asin(sin(beta)*cos_e + cos(beta)*sin_e*sin_l);
}
/* lazy test to ensure gregorian calendar */
if (y < 1583) {
- printf("WHOOPS! Julian dates only valid for 1582 oct 15 or later\n");
+ FG_LOG( FG_EVENT, FG_ALERT,
+ "WHOOPS! Julian dates only valid for 1582 oct 15 or later" );
}
if ((m == 1) || (m == 2)) {
/* lambda = sun_ecliptic_longitude(ssue); */
/* ecliptic_to_equatorial(lambda, 0.0, &alpha, &delta); */
- ecliptic_to_equatorial (solarPosition.lonSun, 0.0, &alpha, &delta);
-
+ //ecliptic_to_equatorial (solarPosition.lonSun, 0.0, &alpha, &delta);
+
+ /* **********************************************************************
+ * NOTE: in the next function, each time the sun's position is updated, the
+ * the sun's longitude is returned from solarSystem->sun. Note that the
+ * sun's position is updated at a much higher frequency than the rate at
+ * which the solar system's rebuilds occur. This is not a problem, however,
+ * because the fgSunPosition we're talking about here concerns the changing
+ * position of the sun due to the daily rotation of the earth.
+ * The ecliptic longitude, however, represents the position of the sun with
+ * respect to the stars, and completes just one cycle over the course of a
+ * year. Its therefore pretty safe to update the sun's longitude only once
+ * every ten minutes. (Comment added by Durk Talsma).
+ ************************************************************************/
+
+ ecliptic_to_equatorial( SolarSystem::theSolarSystem->getSun()->getLon(),
+ 0.0, &alpha, &delta );
tmp = alpha - (FG_2PI/24)*GST(ssue);
if (tmp < -FG_PI) {
do tmp += FG_2PI;
}
+/* given a particular time expressed in side real time at prime
+ * meridian (GST), compute position on the earth (lat, lon) such that
+ * sun is directly overhead. (lat, lon are reported in radians */
+
+static void fgSunPositionGST(double gst, double *lon, double *lat) {
+ /* time_t ssue; seconds since unix epoch */
+ /* double *lat; (return) latitude */
+ /* double *lon; (return) longitude */
+
+ /* double lambda; */
+ double alpha, delta;
+ double tmp;
+
+ /* lambda = sun_ecliptic_longitude(ssue); */
+ /* ecliptic_to_equatorial(lambda, 0.0, &alpha, &delta); */
+ //ecliptic_to_equatorial (solarPosition.lonSun, 0.0, &alpha, &delta);
+ ecliptic_to_equatorial( SolarSystem::theSolarSystem->getSun()->getLon(),
+ SolarSystem::theSolarSystem->getSun()->getLat(),
+ &alpha, &delta );
+
+// tmp = alpha - (FG_2PI/24)*GST(ssue);
+ tmp = alpha - (FG_2PI/24)*gst;
+ if (tmp < -FG_PI) {
+ do tmp += FG_2PI;
+ while (tmp < -FG_PI);
+ } else if (tmp > FG_PI) {
+ do tmp -= FG_2PI;
+ while (tmp < -FG_PI);
+ }
+
+ *lon = tmp;
+ *lat = delta;
+}
+
+
// update the cur_time_params structure with the current sun position
void fgUpdateSunPos( void ) {
- struct fgLIGHT *l;
- struct fgTIME *t;
- struct fgVIEW *v;
- MAT3vec nup, nsun, v0;
+ fgLIGHT *l;
+ fgTIME *t;
+ FGView *v;
+ MAT3vec nup, nsun, v0, surface_to_sun;
+ Point3D p, rel_sunpos;
+ double dot, east_dot;
double sun_gd_lat, sl_radius;
double ntmp;
t = &cur_time_params;
v = ¤t_view;
- printf(" Updating Sun position\n");
+ FG_LOG( FG_EVENT, FG_INFO, " Updating Sun position" );
- fgSunPosition(t->cur_time, &l->sun_lon, &sun_gd_lat);
- fgSunPosition(t->cur_time, &l->sun_lon, &sun_gd_lat);
+ // (not sure why there was two)
+ // fgSunPosition(t->cur_time, &l->sun_lon, &sun_gd_lat);
+ fgSunPositionGST(t->gst, &l->sun_lon, &sun_gd_lat);
fgGeodToGeoc(sun_gd_lat, 0.0, &sl_radius, &l->sun_gc_lat);
- l->fg_sunpos = fgPolarToCart(l->sun_lon, l->sun_gc_lat, sl_radius);
+ p = Point3D( l->sun_lon, l->sun_gc_lat, sl_radius );
+ l->fg_sunpos = fgPolarToCart3d(p);
- printf( " t->cur_time = %ld\n", t->cur_time);
- printf( " Sun Geodetic lat = %.5f Geocentric lat = %.5f\n",
- sun_gd_lat, l->sun_gc_lat);
+ FG_LOG( FG_EVENT, FG_INFO, " t->cur_time = " << t->cur_time );
+ FG_LOG( FG_EVENT, FG_INFO,
+ " Sun Geodetic lat = " << sun_gd_lat
+ << " Geocentric lat = " << l->sun_gc_lat );
// I think this will work better for generating the sun light vector
- l->sun_vec[0] = l->fg_sunpos.x;
- l->sun_vec[1] = l->fg_sunpos.y;
- l->sun_vec[2] = l->fg_sunpos.z;
+ l->sun_vec[0] = l->fg_sunpos.x();
+ l->sun_vec[1] = l->fg_sunpos.y();
+ l->sun_vec[2] = l->fg_sunpos.z();
MAT3_NORMALIZE_VEC(l->sun_vec, ntmp);
MAT3_SCALE_VEC(l->sun_vec_inv, l->sun_vec, -1.0);
l->sun_vec[3] = 0.0;
l->sun_vec_inv[3] = 0.0;
- printf(" l->sun_vec = %.2f %.2f %.2f\n", l->sun_vec[0], l->sun_vec[1],
- l->sun_vec[2]);
+ // printf(" l->sun_vec = %.2f %.2f %.2f\n", l->sun_vec[0], l->sun_vec[1],
+ // l->sun_vec[2]);
// calculate the sun's relative angle to local up
- MAT3_COPY_VEC(nup, v->local_up);
- nsun[0] = l->fg_sunpos.x;
- nsun[1] = l->fg_sunpos.y;
- nsun[2] = l->fg_sunpos.z;
+ MAT3_COPY_VEC(nup, v->get_local_up());
+ nsun[0] = l->fg_sunpos.x();
+ nsun[1] = l->fg_sunpos.y();
+ nsun[2] = l->fg_sunpos.z();
MAT3_NORMALIZE_VEC(nup, ntmp);
MAT3_NORMALIZE_VEC(nsun, ntmp);
l->sun_angle = acos(MAT3_DOT_PRODUCT(nup, nsun));
- printf(" SUN ANGLE relative to current location = %.3f rads.\n",
- l->sun_angle);
+ // printf(" SUN ANGLE relative to current location = %.3f rads.\n",
+ // l->sun_angle);
// calculate vector to sun's position on the earth's surface
- v->to_sun[0] = l->fg_sunpos.x - (v->view_pos.x + scenery.center.x);
- v->to_sun[1] = l->fg_sunpos.y - (v->view_pos.y + scenery.center.y);
- v->to_sun[2] = l->fg_sunpos.z - (v->view_pos.z + scenery.center.z);
+ rel_sunpos = l->fg_sunpos - (v->get_view_pos() + scenery.center);
+ v->set_to_sun( rel_sunpos.x(), rel_sunpos.y(), rel_sunpos.z() );
// printf( "Vector to sun = %.2f %.2f %.2f\n",
// v->to_sun[0], v->to_sun[1], v->to_sun[2]);
// make a vector to the current view position
- MAT3_SET_VEC(v0, v->view_pos.x, v->view_pos.y, v->view_pos.z);
+ Point3D view_pos = v->get_view_pos();
+ MAT3_SET_VEC(v0, view_pos.x(), view_pos.y(), view_pos.z());
// Given a vector from the view position to the point on the
// earth's surface the sun is directly over, map into onto the
// local plane representing "horizontal".
- map_vec_onto_cur_surface_plane(v->local_up, v0, v->to_sun,
- v->surface_to_sun);
- MAT3_NORMALIZE_VEC(v->surface_to_sun, ntmp);
+ map_vec_onto_cur_surface_plane( v->get_local_up(), v0, v->get_to_sun(),
+ surface_to_sun );
+ MAT3_NORMALIZE_VEC(surface_to_sun, ntmp);
+ v->set_surface_to_sun( surface_to_sun[0], surface_to_sun[1],
+ surface_to_sun[2] );
// printf("Surface direction to sun is %.2f %.2f %.2f\n",
// v->surface_to_sun[0], v->surface_to_sun[1], v->surface_to_sun[2]);
// printf("Should be close to zero = %.2f\n",
// MAT3_DOT_PRODUCT(v->local_up, v->surface_to_sun));
+
+ // calculate the angle between v->surface_to_sun and
+ // v->surface_east. We do this so we can sort out the acos()
+ // ambiguity. I wish I could think of a more efficient way ... :-(
+ east_dot = MAT3_DOT_PRODUCT( surface_to_sun, v->get_surface_east() );
+ // printf(" East dot product = %.2f\n", east_dot);
+
+ // calculate the angle between v->surface_to_sun and
+ // v->surface_south. this is how much we have to rotate the sky
+ // for it to align with the sun
+ dot = MAT3_DOT_PRODUCT( surface_to_sun, v->get_surface_south() );
+ // printf(" Dot product = %.2f\n", dot);
+ if ( east_dot >= 0 ) {
+ l->sun_rotation = acos(dot);
+ } else {
+ l->sun_rotation = -acos(dot);
+ }
+ // printf(" Sky needs to rotate = %.3f rads = %.1f degrees.\n",
+ // angle, angle * RAD_TO_DEG); */
}
// $Log$
+// Revision 1.21 1999/03/22 02:08:18 curt
+// Changes contributed by Durk Talsma:
+//
+// Here's a few changes I made to fg-0.58 this weekend. Included are the
+// following features:
+// - Sun and moon have a halo
+// - The moon has a light vector, moon_angle, etc. etc. so that we can have
+// some moonlight during the night.
+// - Lot's of small changes tweakes, including some stuff Norman Vine sent
+// me earlier.
+//
+// Revision 1.20 1999/02/26 22:10:11 curt
+// Added initial support for native SGI compilers.
+//
+// Revision 1.19 1999/01/07 20:25:37 curt
+// Portability changes and updates from Bernie Bright.
+//
+// Revision 1.18 1998/12/09 18:50:36 curt
+// Converted "class fgVIEW" to "class FGView" and updated to make data
+// members private and make required accessor functions.
+//
+// Revision 1.17 1998/11/09 23:41:53 curt
+// Log message clean ups.
+//
+// Revision 1.16 1998/11/07 19:07:14 curt
+// Enable release builds using the --without-logging option to the configure
+// script. Also a couple log message cleanups, plus some C to C++ comment
+// conversion.
+//
+// Revision 1.15 1998/10/18 01:17:24 curt
+// Point3D tweaks.
+//
+// Revision 1.14 1998/10/17 01:34:32 curt
+// C++ ifying ...
+//
+// Revision 1.13 1998/10/16 00:56:12 curt
+// Converted to Point3D class.
+//
+// Revision 1.12 1998/09/15 04:27:50 curt
+// Changes for new astro code.
+//
+// Revision 1.11 1998/08/12 21:13:22 curt
+// Optimizations by Norman Vine.
+//
+// Revision 1.10 1998/07/22 21:45:39 curt
+// fg_time.cxx: Removed call to ctime() in a printf() which should be harmless
+// but seems to be triggering a bug.
+// light.cxx: Added code to adjust fog color based on sunrise/sunset effects
+// and view orientation. This is an attempt to match the fog color to the
+// sky color in the center of the screen. You see discrepancies at the
+// edges, but what else can be done?
+// sunpos.cxx: Caculate local direction to sun here. (what compass direction
+// do we need to face to point directly at sun)
+//
+// Revision 1.9 1998/07/08 14:48:39 curt
+// polar3d.h renamed to polar3d.hxx
+//
+// Revision 1.8 1998/05/02 01:53:18 curt
+// Fine tuning mktime() support because of varying behavior on different
+// platforms.
+//
+// Revision 1.7 1998/04/30 12:36:05 curt
+// C++-ifying a couple source files.
+//
+// Revision 1.6 1998/04/28 01:22:18 curt
+// Type-ified fgTIME and fgVIEW.
+//
+// Revision 1.5 1998/04/26 05:10:05 curt
+// "struct fgLIGHT" -> "fgLIGHT" because fgLIGHT is typedef'd.
+//
+// Revision 1.4 1998/04/25 22:06:34 curt
+// Edited cvs log messages in source files ... bad bad bad!
+//
// Revision 1.3 1998/04/25 20:24:03 curt
// Cleaned up initialization sequence to eliminate interdependencies
// between sun position, lighting, and view position. This creates a
// Minor tweaks.
//
// Revision 1.24 1998/01/27 00:48:07 curt
-// Incorporated Paul Bleisch's <bleisch@chromatic.com> new debug message
+// Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
// system and commandline/config file processing code.
//
// Revision 1.23 1998/01/19 19:27:21 curt
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