1 /**************************************************************************
4 * Written 1997 by Durk Talsma, started October, 1997. For the flight gear
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation; either version 2 of the
10 * License, or (at your option) any later version.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 * (Log is kept at end of this file)
23 **************************************************************************/
33 #include <Time/fg_time.h>
34 #include <Astro/orbits.h>
35 #include <Astro/planets.h>
36 #include <Astro/sun.h>
37 #include <Include/fg_constants.h>
38 #include <Main/fg_debug.h>
42 struct CelestialCoord fgCalculatePlanet(struct OrbElements planet,
43 struct OrbElements theSun,
44 struct fgTIME t, int idx)
46 struct CelestialCoord result;
48 fgSUNPOS SolarPosition;
50 double eccAnom, r, v, ecl, actTime, R, s, ir, Nr, B, FV, ring_magn,
51 xv, yv, xh, yh, zh, xg, yg, zg, xe, ye, ze;
53 actTime = fgCalcActTime(t);
54 /*calculate the angle between ecliptic and equatorial coordinate system */
55 ecl = DEG_TO_RAD * (23.4393 - 3.563E-7 * actTime);
57 /* calculate the eccentric anomaly */
58 eccAnom = fgCalcEccAnom(planet.M, planet.e);
60 /* calculate the planets distance (r) and true anomaly (v) */
61 xv = planet.a * (cos(eccAnom) - planet.e);
62 yv = planet.a * (sqrt(1.0 - planet.e*planet.e) * sin(eccAnom));
64 r = sqrt ( xv*xv + yv*yv);
66 /* calculate the planets position in 3-dimensional space */
67 xh = r * (cos (planet.N) * cos (v + planet.w) -
68 sin (planet.N) * sin (v + planet.w) * cos (planet.i));
69 yh = r * (sin (planet.N) * cos (v + planet.w) +
70 cos (planet.N) * sin (v + planet.w) * cos (planet.i));
71 zh = r * ( sin(v+planet.w) * sin(planet.i));
73 /* calculate the ecliptic longitude and latitude */
75 xg = xh + solarPosition.xs;
76 yg = yh + solarPosition.ys;
80 ye = yg * cos(ecl) - zg * sin(ecl);
81 ze = yg * sin(ecl) + zg * cos(ecl);
83 result.RightAscension = atan2(ye,xe);
84 result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
86 /* Let's calculate the brightness of the planet */
87 R = sqrt ( xg*xg + yg*yg + zg*zg);
88 s = SolarPosition.dist;
89 FV = acos( (r*r + R*R - s*s) / (2*r*R));
90 FV *= 57.29578; /* convert radians to degrees */
94 result.magnitude = -0.36 + 5*log10( r*R ) + 0.027 * FV + 2.2E-13 * pow(FV, 6);
97 result.magnitude = -4.34 + 5*log10( r*R ) + 0.013 * FV + 4.2E-07 * pow(FV,3);
100 result.magnitude = -1.51 + 5*log10( r*R ) + 0.016 * FV;
102 case 5: /* Jupiter */
103 result.magnitude = -9.25 + 5*log10( r*R ) + 0.014 * FV;
108 Nr = 2.9585076 + 6.6672E-7*actTime;
110 B = asin (sin (result.Declination) * cos (ir) -
111 cos (result.Declination) * sin (ir) *
112 sin (result.RightAscension - Nr));
113 ring_magn = -2.6 * sin (fabs(B)) + 1.2 * pow(sin(B),2);
114 result.magnitude = -9.0 + 5*log10( r*R ) + 0.044 * FV + ring_magn;
117 result.magnitude = -7.15 + 5*log10( r*R) + 0.001 * FV;
119 case 8: /* Neptune */
120 result.magnitude = -6.90 + 5*log10 (r*R) + 0.001 *FV;
123 fgPrintf( FG_ASTRO, FG_ALERT, "index %d out of range !!!!\n", idx);
125 fgPrintf( FG_ASTRO, FG_DEBUG,
126 " Planet found at %f (ra), %f (dec)\n",
127 result.RightAscension, result.Declination);
128 fgPrintf( FG_ASTRO, FG_DEBUG,
129 " Geocentric dist %f\n"
130 " Heliocentric dist %f\n"
131 " Distance to the sun %f\n"
133 " Brightness %f\n", R, r, s, FV, result.magnitude);
138 void fgPlanetsInit( void )
142 struct CelestialCoord pltPos;
145 l = &cur_light_params;
146 /* if the display list was already built during a previous init,
150 xglDeleteLists(planets, 1);
153 planets = xglGenLists(1);
154 xglNewList( planets, GL_COMPILE );
155 xglBegin( GL_POINTS );
158 /* Add the planets to all four display lists */
159 for ( i = 2; i < 9; i++ ) {
160 fgSolarSystemUpdate(&(pltOrbElements[i]), cur_time_params);
161 pltPos = fgCalculatePlanet(pltOrbElements[i],
162 pltOrbElements[0], cur_time_params, i);
164 magnitude = (0.0 - pltPos.magnitude) / 5.0 + 1.0;
166 /* scale magnitudes again so they look ok */
168 magnitude * 0.7 + (((FG_STAR_LEVELS - 1) - i) * 0.1); */
170 /* the following statement could be made a little more sopisticated
171 for the moment: Stick to this one */
172 magnitude = magnitude * 0.7 + (3 * 0.1);
173 if ( magnitude > 1.0 ) { magnitude = 1.0; }
174 if ( magnitude < 0.0 ) { magnitude = 0.0; }
176 /* Add planets to the display list, based on sun_angle and current
177 magnitude It's pretty experimental... */
179 if ((double) (l->sun_angle - FG_PI_2) >
180 ((magnitude - 1.0) * -20 * DEG_TO_RAD))
182 xglColor3f (magnitude, magnitude, magnitude);
183 printf ("Sun Angle to Horizon (in Rads) = %f\n",
184 (double) (l->sun_angle - FG_PI_2));
185 printf ("Transformed Magnitude is :%f %f\n",
186 magnitude, (magnitude - 1.0) * -20 * DEG_TO_RAD);
188 xglVertex3f (50000.0 * cos (pltPos.RightAscension) *
189 cos (pltPos.Declination),
190 50000.0 * sin (pltPos.RightAscension) *
191 cos (pltPos.Declination),
192 50000.0 * sin (pltPos.Declination));
201 void fgPlanetsRender( void ) {
202 xglCallList(planets);
207 /* Revision 1.7 1998/02/23 19:07:55 curt
208 /* Incorporated Durk's Astro/ tweaks. Includes unifying the sun position
209 /* calculation code between sun display, and other FG sections that use this
210 /* for things like lighting.
212 * Revision 1.6 1998/02/12 21:59:36 curt
213 * Incorporated code changes contributed by Charlie Hotchkiss
214 * <chotchkiss@namg.us.anritsu.com>
216 * Revision 1.5 1998/02/03 23:20:12 curt
217 * Lots of little tweaks to fix various consistency problems discovered by
218 * Solaris' CC. Fixed a bug in fg_debug.c with how the fgPrintf() wrapper
219 * passed arguments along to the real printf(). Also incorporated HUD changes
220 * by Michele America.
222 * Revision 1.4 1998/02/02 20:53:23 curt
225 * Revision 1.3 1998/01/27 00:47:47 curt
226 * Incorporated Paul Bleisch's <bleisch@chromatic.com> new debug message
227 * system and commandline/config file processing code.
229 * Revision 1.2 1998/01/19 19:26:59 curt
230 * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
231 * This should simplify things tremendously.
233 * Revision 1.1 1998/01/07 03:16:18 curt
234 * Moved from .../Src/Scenery/ to .../Src/Astro/
236 * Revision 1.4 1997/12/30 20:47:52 curt
237 * Integrated new event manager with subsystem initializations.
239 * Revision 1.3 1997/12/30 16:36:52 curt
240 * Merged in Durk's changes ...
242 * Revision 1.2 1997/12/12 21:41:29 curt
243 * More light/material property tweaking ... still a ways off.
245 * Revision 1.1 1997/10/25 03:16:10 curt
246 * Initial revision of code contributed by Durk Talsma.