Initial revision of code contributed by Durk Talsma.

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curt 27 years ago
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/**************************************************************************
* moon.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#include <math.h>
#include <GL/glut.h>
#include "orbits.h"
#include "moon.h"
#include "../Time/fg_time.h"
#include "../GLUT/views.h"
/* #include "../Aircraft/aircraft.h"*/
#include "../general.h"
static GLint moon;
struct CelestialCoord fgCalculateMoon(struct OrbElements params,
struct OrbElements sunParams,
struct fgTIME t)
{
struct CelestialCoord
result;
double
eccAnom, ecl, lonecl, latecl, actTime,
xv, yv, v, r, xh, yh, zh, xg, yg, zg, xe, ye, ze,
Ls, Lm, D, F;
/* calculate the angle between ecliptic and equatorial coordinate system */
actTime = fgCalcActTime(t);
ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime); // in radians of course
/* calculate the eccentric anomaly */
eccAnom = fgCalcEccAnom(params.M, params.e);
/* calculate the moon's distance (d) and true anomaly (v) */
xv = params.a * ( cos(eccAnom) - params.e);
yv = params.a * ( sqrt(1.0 - params.e*params.e) * sin(eccAnom));
v =atan2(yv, xv);
r = sqrt(xv*xv + yv*yv);
/* estimate the geocentric rectangular coordinates here */
xh = r * (cos(params.N) * cos(v + params.w) - sin(params.N) * sin(v + params.w) * cos(params.i));
yh = r * (sin(params.N) * cos(v + params.w) + cos(params.N) * sin(v + params.w) * cos(params.i));
zh = r * (sin(v + params.w) * sin(params.i));
/* calculate the ecliptic latitude and longitude here */
lonecl = atan2( yh, xh);
latecl = atan2( zh, sqrt( xh*xh + yh*yh));
/* calculate a number of perturbations */
Ls = sunParams.M + sunParams.w;
Lm = params.M + params.w + params.N;
D = Lm - Ls;
F = Lm - params.N;
lonecl += fgDegToRad(
- 1.274 * sin (params.M - 2*D) // the Evection
+ 0.658 * sin (2 * D) // the Variation
- 0.186 * sin (sunParams.M) // the yearly variation
- 0.059 * sin (2*params.M - 2*D)
- 0.057 * sin (params.M - 2*D + sunParams.M)
+ 0.053 * sin (params.M + 2*D)
+ 0.046 * sin (2*D - sunParams.M)
+ 0.041 * sin (params.M - sunParams.M)
- 0.035 * sin (D) // the Parallactic Equation
- 0.031 * sin (params.M + sunParams.M)
- 0.015 * sin (2*F - 2*D)
+ 0.011 * sin (params.M - 4*D)
); /* Pheeuuwwww */
latecl += fgDegToRad(
- 0.173 * sin (F - 2*D)
- 0.055 * sin (params.M - F - 2*D)
- 0.046 * sin (params.M + F - 2*D)
+ 0.033 * sin (F + 2*D)
+ 0.017 * sin (2 * params.M + F)
); /* Yep */
r += (
- 0.58 * cos(params.M - 2*D)
- 0.46 * cos(2*D)
);
xg = r * cos(lonecl) * cos(latecl);
yg = r * sin(lonecl) * cos(latecl);
zg = r * sin(latecl);
xe = xg;
ye = yg * cos(ecl) - zg * sin(ecl);
ze = yg * sin(ecl) + zg * cos(ecl);
result.RightAscension = atan2(ye, xe);
result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
return result;
}
void fgMoonInit()
{
struct CelestialCoord
moonPos;
moon = glGenLists(1);
glNewList(moon, GL_COMPILE );
glBegin( GL_POINTS );
moonPos = fgCalculateMoon(pltOrbElements[1], pltOrbElements[0], cur_time_params);
printf("Moon found at %f (ra), %f (dec)\n", moonPos.RightAscension, moonPos.Declination);
/* give the moon a temporary color, for testing purposes */
glColor3f( 0.0, 1.0, 0.0);
glVertex3f( 190000.0 * cos(moonPos.RightAscension) * cos(moonPos.Declination),
190000.0 * sin(moonPos.RightAscension) * cos(moonPos.Declination),
190000.0 * sin(moonPos.Declination) );
glEnd();
glEndList();
}
void fgMoonRender()
{
double angle;
static double warp = 0;
struct VIEW *v;
struct fgTIME *t;
t = &cur_time_params;
v = &current_view;
glDisable( GL_FOG );
glDisable( GL_LIGHTING );
glPushMatrix();
glTranslatef( v->view_pos.x, v->view_pos.y, v->view_pos.z );
angle = t->gst * 15.0; /* 15 degrees per hour rotation */
/* warp += 1.0; */
/* warp = 15.0; */
warp = 0.0;
glRotatef( (angle+warp), 0.0, 0.0, -1.0 );
printf("Rotating moon by %.2f degrees + %.2f degrees\n",angle,warp);
glCallList(moon);
glPopMatrix();
glEnable( GL_LIGHTING );
glEnable( GL_FOG );
}
/* $Log$
/* Revision 1.1 1997/10/25 03:16:08 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/

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/**************************************************************************
* moon.h
*
* Written 1997 by Durk Talsma, started October, 1997.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#ifndef _MOON_H_
#define _MOON_H_
#include "orbits.h"
#include "../Time/fg_time.h"
/* Initialize the Moon Display management Subsystem */
void fgMoonInit();
/* Draw the Stars */
void fgMoonRender();
struct CelestialCoord fgCalculateMoon(struct OrbElements Params,
struct OrbElements sunParams,
struct fgTIME t);
extern struct OrbElements pltOrbElements[9];
#endif /* _MOON_H_ */
/* $Log$
/* Revision 1.1 1997/10/25 03:16:09 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/

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/**************************************************************************
* orbits.c - calculates the orbital elements of the sun, moon and planets.
* For inclusion in flight gear
*
* Written 1997 by Durk Talsma, started October 19, 1997.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#include <string.h>
#include "orbits.h"
#include "../general.h"
#include "../Time/fg_time.h"
struct OrbElements pltOrbElements[9];
double fgCalcActTime(struct fgTIME t)
{
double
actTime, UT;
int year;
/* a hack. This one introduces the 2000 problem into the program */
year = t.gmt->tm_year + 1900;
/* calculate the actual time */
actTime = 367 * year - 7 *
(year + (t.gmt->tm_mon + 9) / 12) / 4 + 275 *
t.gmt->tm_mon / 9 + t.gmt->tm_mday - 730530;
UT = t.gmt->tm_hour + ((double) t.gmt->tm_min / 60);
/*printf("UT = %f\n", UT); */
actTime += (UT / 24.0);
printf("current day = %f\t", actTime);
printf("GMT = %d, %d, %d, %d, %d, %d\n", year, t.gmt->tm_mon, t.gmt->tm_mday,
t.gmt->tm_hour, t.gmt->tm_min, t.gmt->tm_sec);
return actTime;
}
/* convert degrees to radians */
double fgDegToRad(double angle)
{
return (angle * PIOVER180);
}
double fgCalcEccAnom(double M, double e)
{
double
eccAnom, E0, E1, diff;
eccAnom = M + e * sin(M) * (1.0 + e * cos(M));
/* iterate to achieve a greater precision for larger eccentricities */
if (e > 0.05)
{
E0 = eccAnom;
do
{
E1 = E0 - (E0 - e * sin(E0) - M) / (1 - e * cos(E0));
diff = abs(E0 - E1);
E0 = E1;
}
while (diff > fgDegToRad(0.001));
return E0;
}
return eccAnom;
}
void fgReadOrbElements(struct OrbElements *dest, FILE *src)
{
char line[256];
int i,j;
j = 0;
do
{
fgets(line, 256,src);
for (i = 0; i < 256; i++)
{
if (line[i] == '#')
line[i] = 0;
}
/*printf("Reading line %d\n", j++); */
}
while (!(strlen(line)));
sscanf(line, "%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf,%lf\n",
&dest->NFirst, &dest->NSec,
&dest->iFirst, &dest->iSec,
&dest->wFirst, &dest->wSec,
&dest->aFirst, &dest->aSec,
&dest->eFirst, &dest->eSec,
&dest->MFirst, &dest->MSec);
}
void fgSolarSystemInit(struct fgTIME t)
{
struct GENERAL *g;
char path[80];
int i;
FILE *data;
/* build the full path name to the orbital elements database file */
g = &general;
path[0] = '\0';
strcat(path, g->root_dir);
strcat(path, "/Scenery/");
strcat(path, "planets.dat");
if ( (data = fopen(path, "r")) == NULL )
{
printf("Cannot open data file: '%s'\n", path);
return;
}
printf("reading datafile %s", path);
/* for all the objects... */
for (i = 0; i < 9; i ++)
{
/* ...read from the data file ... */
fgReadOrbElements(&pltOrbElements[i], data);
/* ...and calculate the actual values */
fgSolarSystemUpdate(&pltOrbElements[i], t);
}
}
void fgSolarSystemUpdate(struct OrbElements *planet, struct fgTIME t)
{
double
actTime;
actTime = fgCalcActTime(t);
/* calculate the actual orbital elements */
planet->M = fgDegToRad(planet->MFirst + (planet->MSec * actTime)); // angle in radians
planet->w = fgDegToRad(planet->wFirst + (planet->wSec * actTime)); // angle in radians
planet->N = fgDegToRad(planet->NFirst + (planet->NSec * actTime)); // angle in radians
planet->i = fgDegToRad(planet->iFirst + (planet->iSec * actTime)); // angle in radians
planet->e = planet->eFirst + (planet->eSec * actTime);
planet->a = planet->aFirst + (planet->aSec * actTime);
}
/* $Log$
/* Revision 1.1 1997/10/25 03:16:10 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/

@ -0,0 +1,85 @@
/**************************************************************************
* orbits.h - calculates the orbital elements of the sun, moon and planets.
* For inclusion in flight gear
*
* Written 1997 by Durk Talsma, started October 19, 1997.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#ifndef ORBITS_H
#define ORBITS_H
#include <stdio.h>
#include <math.h>
#include "../Time/fg_time.h"
#define STANDARDEPOCH 2000
#define PIOVER180 1.74532925199433E-002
struct SunPos {
double xs;
double ys;
};
struct OrbElements {
double NFirst; /* longitude of the ascending node first part */
double NSec; /* longitude of the ascending node second part */
double iFirst; /* inclination to the ecliptic first part */
double iSec; /* inclination to the ecliptic second part */
double wFirst; /* first part of argument of perihelion */
double wSec; /* second part of argument of perihelion */
double aFirst; /* semimayor axis first part*/
double aSec; /* semimayor axis second part */
double eFirst; /* eccentricity first part */
double eSec; /* eccentricity second part */
double MFirst; /* Mean anomaly first part */
double MSec; /* Mean anomaly second part */
double N, i, w, a, e, M; /* the resultant orbital elements, obtained from the former */
};
struct CelestialCoord {
double RightAscension;
double Declination;
double distance;
};
double fgDegToRad(double angle);
double fgCalcEccAnom(double M, double e);
double fgCalcActTime(struct fgTIME t);
void fgReadOrbElements(struct OrbElements *dest, FILE *src);
void fgSolarSystemInit(struct fgTIME t);
void fgSolarSystemUpdate(struct OrbElements *planets, struct fgTIME t);
#endif /* ORBITS_H */
/* $Log$
/* Revision 1.1 1997/10/25 03:16:10 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/

@ -0,0 +1,91 @@
/**************************************************************************
* planets.c
*
* Written 1997 by Durk Talsma, started October, 1997. For the flight gear
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#include "../Time/fg_time.h"
#include "orbits.h"
#include "planets.h"
#include "sun.h"
struct CelestialCoord fgCalculatePlanet(struct OrbElements planet,
struct OrbElements sun,
struct fgTIME t)
{
struct CelestialCoord
result;
struct SunPos
SolarPosition;
double
eccAnom, r, v, ecl, actTime,
xv, yv, xh, yh, zh, xg, yg, zg, xe, ye, ze;
actTime = fgCalcActTime(t);
/* calculate the angle between ecliptic and equatorial coordinate system */
ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime);
/* calculate the eccentric anomaly */
eccAnom = fgCalcEccAnom(planet.M, planet.e);
/* calculate the planets distance (r) and true anomaly (v) */
xv = planet.a * (cos(eccAnom) - planet.e);
yv = planet.a * (sqrt(1.0 - planet.e*planet.e) * sin(eccAnom));
v = atan2(yv, xv);
r = sqrt ( xv*xv + yv*yv);
/* calculate the planets position in 3-dimensional space */
xh = r * ( cos(planet.N) * cos(v+planet.w) - sin(planet.N) * sin(v+planet.w) * cos(planet.i));
yh = r * ( sin(planet.N) * cos(v+planet.w) + cos(planet.N) * sin(v+planet.w) * cos(planet.i));
zh = r * ( sin(v+planet.w) * sin(planet.i));
/* calculate the ecleptic longitude and latitude */
/*
lonecl = atan2(yh, xh);
latecl = atan2(zh, sqrt ( xh*xh + yh*yh));
*/
/* calculate the solar position */
SolarPosition = fgCalcSunPos(sun);
xg = xh + SolarPosition.xs;
yg = yh + SolarPosition.ys;
zg = zh;
xe = xg;
ye = yg * cos(ecl) - zg * sin(ecl);
ze = yg * sin(ecl) + zg * cos(ecl);
result.RightAscension = atan2(ye,xe);
result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
return result;
}
/* $Log$
/* Revision 1.1 1997/10/25 03:16:10 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/

@ -0,0 +1,41 @@
/**************************************************************************
* planets.h
*
* Written 1997 by Durk Talsma, started October, 1997. For the flight gear
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#ifndef PLANETS_H
#define PLANETS_H
struct CelestialCoord fgCalculatePlanet(struct OrbElements planet,
struct OrbElements sun,
struct fgTIME t);
#endif /* PLANETS_H */
/* $Log$
/* Revision 1.1 1997/10/25 03:16:11 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/

@ -0,0 +1,61 @@
/**************************************************************************
* sun.c
*
* Written 1997 by Durk Talsma, started October, 1997. For the flight gear
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#include "../Time/fg_time.h"
#include "orbits.h"
struct SunPos fgCalcSunPos(struct OrbElements params)
{
double
EccAnom, lonSun,
xv, yv, v, r;
struct SunPos
solarPosition;
/* calculate the eccentric anomaly */
EccAnom = fgCalcEccAnom(params.M, params.e);
/* calculate the Suns distance (r) and its true anomaly (v) */
xv = cos(EccAnom) - params.e;
yv = sqrt(1.0 - params.e*params.e) * sin(EccAnom);
v = atan2(yv, xv);
r = sqrt(xv*xv + yv*yv);
/* calculate the the Suns true longitude (lonsun) */
lonSun = v + params.w;
/* convert true longitude and distance to ecliptic rectangular geocentric
coordinates (xs, ys) */
solarPosition.xs = r * cos(lonSun);
solarPosition.ys = r * sin(lonSun);
return solarPosition;
}
/* $Log$
/* Revision 1.1 1997/10/25 03:16:11 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/

@ -0,0 +1,40 @@
/**************************************************************************
* sun.h
*
* Written 1997 by Durk Talsma, started October, 1997. For the flight gear
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#ifndef SUN_H
#define SUN_H
struct SunPos fgCalcSunPos(struct OrbElements sunParams);
#endif /* SUN_H */
/* $Log$
/* Revision 1.1 1997/10/25 03:16:12 curt
/* Initial revision of code contributed by Durk Talsma.
/*
*/
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