/**************************************************************************
* 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)
**************************************************************************/
#ifdef WIN32
# include <windows.h>
#endif
#include <GL/glut.h>
#include <XGL/xgl.h>
#include <Time/fg_time.h>
#include <Astro/orbits.h>
#include <Astro/planets.h>
#include <Astro/sun.h>
#include <Include/fg_constants.h>
#include <Main/fg_debug.h>
GLint planets = 0;
struct CelestialCoord fgCalculatePlanet(struct OrbElements planet,
struct OrbElements theSun,
struct fgTIME t, int idx)
{
struct CelestialCoord result;
fgSUNPOS 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 = DEG_TO_RAD * (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 ecliptic longitude and latitude */
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 (fabs(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:
fgPrintf( FG_ASTRO, FG_ALERT, "index %d out of range !!!!\n", idx);
}
fgPrintf( FG_ASTRO, FG_DEBUG,
" Planet found at %f (ra), %f (dec)\n",
result.RightAscension, result.Declination);
fgPrintf( FG_ASTRO, FG_DEBUG,
" 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;
}
void fgPlanetsInit( void )
{
struct fgLIGHT *l;
int i;
struct CelestialCoord pltPos;
double magnitude;
l = &cur_light_params;
/* if the display list was already built during a previous init,
then recycle it */
if (planets) {
xglDeleteLists(planets, 1);
}
planets = xglGenLists(1);
xglNewList( planets, GL_COMPILE );
xglBegin( GL_POINTS );
/* Add the planets to all four display lists */
for ( i = 2; i < 9; i++ ) {
fgSolarSystemUpdate(&(pltOrbElements[i]), cur_time_params);
pltPos = fgCalculatePlanet(pltOrbElements[i],
pltOrbElements[0], cur_time_params, i);
magnitude = (0.0 - pltPos.magnitude) / 5.0 + 1.0;
/* scale magnitudes again so they look ok */
/* magnitude =
magnitude * 0.7 + (((FG_STAR_LEVELS - 1) - i) * 0.1); */
/* the following statement could be made a little more sopisticated
for the moment: Stick to this one */
magnitude = magnitude * 0.7 + (3 * 0.1);
if ( magnitude > 1.0 ) { magnitude = 1.0; }
if ( magnitude < 0.0 ) { magnitude = 0.0; }
/* Add planets to the display list, based on sun_angle and current
magnitude It's pretty experimental... */
if ((double) (l->sun_angle - FG_PI_2) >
((magnitude - 1.0) * -20 * DEG_TO_RAD))
{
xglColor3f (magnitude, magnitude, magnitude);
printf ("Sun Angle to Horizon (in Rads) = %f\n",
(double) (l->sun_angle - FG_PI_2));
printf ("Transformed Magnitude is :%f %f\n",
magnitude, (magnitude - 1.0) * -20 * DEG_TO_RAD);
xglVertex3f (50000.0 * cos (pltPos.RightAscension) *
cos (pltPos.Declination),
50000.0 * sin (pltPos.RightAscension) *
cos (pltPos.Declination),
50000.0 * sin (pltPos.Declination));
}
}
xglEnd();
xglEndList();
}
void fgPlanetsRender( void ) {
xglCallList(planets);
}
/* $Log$
/* Revision 1.7 1998/02/23 19:07:55 curt
/* Incorporated Durk's Astro/ tweaks. Includes unifying the sun position
/* calculation code between sun display, and other FG sections that use this
/* for things like lighting.
/*
* Revision 1.6 1998/02/12 21:59:36 curt
* Incorporated code changes contributed by Charlie Hotchkiss
* <chotchkiss@namg.us.anritsu.com>
*
* Revision 1.5 1998/02/03 23:20:12 curt
* Lots of little tweaks to fix various consistency problems discovered by
* Solaris' CC. Fixed a bug in fg_debug.c with how the fgPrintf() wrapper
* passed arguments along to the real printf(). Also incorporated HUD changes
* by Michele America.
*
* Revision 1.4 1998/02/02 20:53:23 curt
* To version 0.29
*
* Revision 1.3 1998/01/27 00:47:47 curt
* Incorporated Paul Bleisch's <bleisch@chromatic.com> new debug message
* system and commandline/config file processing code.
*
* 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.
*
*/