157 lines
5 KiB
C
157 lines
5 KiB
C
/**************************************************************************
|
|
* 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 <Astro/orbits.h>
|
|
#include <Astro/planets.h>
|
|
#include <Astro/sun.h>
|
|
|
|
|
|
struct CelestialCoord fgCalculatePlanet(struct OrbElements planet,
|
|
struct OrbElements theSun,
|
|
struct fgTIME t, int idx)
|
|
{
|
|
struct CelestialCoord
|
|
result;
|
|
|
|
struct SunPos
|
|
SolarPosition;
|
|
|
|
double
|
|
eccAnom, r, v, ecl, actTime, R, s, ir, Nr, B, FV, ring_magn,
|
|
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(theSun);
|
|
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));
|
|
|
|
|
|
/* Let's calculate the brightness of the planet */
|
|
R = sqrt ( xg*xg + yg*yg + zg*zg);
|
|
s = SolarPosition.dist;
|
|
FV = acos( (r*r + R*R - s*s) / (2*r*R));
|
|
FV *= 57.29578; /* convert radians to degrees */
|
|
switch(idx)
|
|
{
|
|
case 2: /* mercury */
|
|
result.magnitude = -0.36 + 5*log10( r*R ) + 0.027 * FV + 2.2E-13 * pow(FV, 6);
|
|
break;
|
|
case 3: /*venus */
|
|
result.magnitude = -4.34 + 5*log10( r*R ) + 0.013 * FV + 4.2E-07 * pow(FV,3);
|
|
break;
|
|
case 4: /* mars */
|
|
result.magnitude = -1.51 + 5*log10( r*R ) + 0.016 * FV;
|
|
break;
|
|
case 5: /* Jupiter */
|
|
result.magnitude = -9.25 + 5*log10( r*R ) + 0.014 * FV;
|
|
break;
|
|
case 6: /* Saturn */
|
|
|
|
ir = 0.4897394;
|
|
Nr = 2.9585076 + 6.6672E-7*actTime;
|
|
|
|
B = asin ( sin (result.Declination) * cos(ir) - cos(result.Declination) * sin (ir) * sin (result.RightAscension - Nr));
|
|
ring_magn = -2.6 * sin (abs(B)) + 1.2 * pow(sin(B),2);
|
|
result.magnitude = -9.0 + 5*log10( r*R ) + 0.044 * FV + ring_magn;
|
|
break;
|
|
case 7: /* Uranus */
|
|
result.magnitude = -7.15 + 5*log10( r*R) + 0.001 * FV;
|
|
break;
|
|
case 8: /* Neptune */
|
|
result.magnitude = -6.90 + 5*log10 (r*R) + 0.001 *FV;
|
|
break;
|
|
default:
|
|
printf("index %d out of range !!!!\n", idx);
|
|
}
|
|
printf(" Planet found at %f (ra), %f (dec)\n",
|
|
result.RightAscension, result.Declination);
|
|
printf(" Geocentric dist %f\n"
|
|
" Heliocentric dist %f\n"
|
|
" Distance to the sun %f\n"
|
|
" Phase angle %f\n"
|
|
" Brightness %f\n", R, r, s, FV, result.magnitude);
|
|
return result;
|
|
}
|
|
|
|
|
|
|
|
/* $Log$
|
|
/* Revision 1.2 1998/01/19 19:26:59 curt
|
|
/* Merged in make system changes from Bob Kuehne <rpk@sgi.com>
|
|
/* This should simplify things tremendously.
|
|
/*
|
|
* Revision 1.1 1998/01/07 03:16:18 curt
|
|
* Moved from .../Src/Scenery/ to .../Src/Astro/
|
|
*
|
|
* Revision 1.4 1997/12/30 20:47:52 curt
|
|
* Integrated new event manager with subsystem initializations.
|
|
*
|
|
* Revision 1.3 1997/12/30 16:36:52 curt
|
|
* Merged in Durk's changes ...
|
|
*
|
|
* Revision 1.2 1997/12/12 21:41:29 curt
|
|
* More light/material property tweaking ... still a ways off.
|
|
*
|
|
* Revision 1.1 1997/10/25 03:16:10 curt
|
|
* Initial revision of code contributed by Durk Talsma.
|
|
*
|
|
*/
|
|
|
|
|