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 **************************************************************************/
28 #include <Astro/orbits.h>
29 #include <Astro/sun.h>
30 #include <Include/fg_constants.h>
31 #include <Main/fg_debug.h>
32 #include <Main/views.h>
33 #include <Time/fg_time.h>
34 #include <Time/sunpos.h>
38 static struct CelestialCoord sunPos;
40 fgSUNPOS solarPosition;
42 void fgCalcSunPos(struct OrbElements params)
44 double EccAnom, xv, yv, v, r;
46 /* calculate the eccentric anomaly */
47 EccAnom = fgCalcEccAnom(params.M, params.e);
49 /* calculate the Suns distance (r) and its true anomaly (v) */
50 xv = cos(EccAnom) - params.e;
51 yv = sqrt(1.0 - params.e*params.e) * sin(EccAnom);
53 r = sqrt(xv*xv + yv*yv);
55 /* calculate the the Sun's true longitude (lonsun) */
56 solarPosition.lonSun = v + params.w;
58 /* convert true longitude and distance to ecliptic rectangular
59 geocentric coordinates (xs, ys) */
60 solarPosition.xs = r * cos (solarPosition.lonSun);
61 solarPosition.ys = r * sin (solarPosition.lonSun);
62 solarPosition.dist = r;
63 /* return solarPosition; */
67 struct CelestialCoord fgCalculateSun(struct OrbElements params, struct fgTIME t)
69 struct CelestialCoord result;
70 double xe, ye, ze, ecl, actTime;
72 /* calculate the angle between ecliptic and equatorial coordinate system */
73 actTime = fgCalcActTime(t);
74 ecl = DEG_TO_RAD * (23.4393 - 3.563E-7 * actTime); // Angle now in Rads
76 /* convert ecliptic coordinates to equatorial rectangular
77 geocentric coordinates */
78 xe = solarPosition.xs;
79 ye = solarPosition.ys * cos (ecl);
80 ze = solarPosition.ys * sin (ecl);
82 /* and finally... Calulate Right Ascention and Declination */
83 result.RightAscension = atan2( ye, xe);
84 result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
89 /* Initialize the Sun */
90 void fgSunInit( void ) {
94 float xSun, ySun, zSun;
96 /* GLfloat color[4] = { 1.00, 1.00, 1.00, 1.00 }; */
97 double x_2, x_4, x_8, x_10;
101 l = &cur_light_params;
102 t = &cur_time_params;
105 fgPrintf( FG_ASTRO, FG_INFO, " Initializing the Sun\n");
107 // Calculate basic sun position
108 fgSolarSystemUpdate(&(pltOrbElements[0]), cur_time_params);
109 sunPos = fgCalculateSun(pltOrbElements[0], cur_time_params);
111 // Calculate additional sun position parameters based on the above
112 // position that are needed by other parts of FG
115 fgPrintf( FG_ASTRO, FG_INFO,
116 "Sun found at %f (ra), %f (dec)\n",
117 sunPos.RightAscension, sunPos.Declination);
119 xSun = 60000.0 * cos(sunPos.RightAscension) * cos(sunPos.Declination);
120 ySun = 60000.0 * sin(sunPos.RightAscension) * cos(sunPos.Declination);
121 zSun = 60000.0 * sin(sunPos.Declination);
125 xglDeleteLists(sun_obj, 1);
128 /* printf("First time through, creating sun display list\n"); */
130 sun_obj = xglGenLists(1);
131 xglNewList(sun_obj, GL_COMPILE );
134 t = &cur_time_params;
136 l = &cur_light_params;
138 x_2 = l->sun_angle * l->sun_angle;
143 ambient = (0.4 * pow(1.1, -x_10 / 30.0));
144 if ( ambient < 0.3 ) ambient = 0.3;
145 if ( ambient > 1.0 ) ambient = 1.0;
147 amb[0] = 0.00 + ((ambient * 6.0) - 1.0); /* minimum val = 0.8 */
148 amb[1] = 0.00 + ((ambient * 11.0) - 3.0); /* minimum val = 0.3 */
149 amb[2] = 0.00 + ((ambient * 12.0) - 3.6); /* minimum val = 0.0 */
152 if (amb[0] > 1.0) amb[0] = 1.0;
153 if (amb[1] > 1.0) amb[1] = 1.0;
154 if (amb[2] > 1.0) amb[2] = 1.0;
156 fgPrintf( FG_ASTRO, FG_DEBUG,
157 "Color of the sun: %f, %f, %f\n"
158 "Ambient value : %f\n"
160 amb[0], amb[1], amb[2], ambient, l->sun_angle);
163 xglTranslatef(xSun, ySun, zSun);
164 xglScalef(1400, 1400, 1400);
165 xglColor3f(amb[0], amb[1], amb[2]);
166 glutSolidSphere(1.0, 10, 10);
173 void fgSunRender( void ) {
174 xglCallList(sun_obj);
179 /* Revision 1.7 1998/02/23 19:07:56 curt
180 /* Incorporated Durk's Astro/ tweaks. Includes unifying the sun position
181 /* calculation code between sun display, and other FG sections that use this
182 /* for things like lighting.
184 * Revision 1.6 1998/02/12 21:59:39 curt
185 * Incorporated code changes contributed by Charlie Hotchkiss
186 * <chotchkiss@namg.us.anritsu.com>
188 * Revision 1.5 1998/02/02 20:53:24 curt
191 * Revision 1.4 1998/01/27 00:47:50 curt
192 * Incorporated Paul Bleisch's <bleisch@chromatic.com> new debug message
193 * system and commandline/config file processing code.
195 * Revision 1.3 1998/01/19 19:27:00 curt
196 * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
197 * This should simplify things tremendously.
199 * Revision 1.2 1998/01/19 18:40:18 curt
200 * Tons of little changes to clean up the code and to remove fatal errors
201 * when building with the c++ compiler.
203 * Revision 1.1 1998/01/07 03:16:20 curt
204 * Moved from .../Src/Scenery/ to .../Src/Astro/
206 * Revision 1.12 1998/01/05 18:44:36 curt
207 * Add an option to advance/decrease time from keyboard.
209 * Revision 1.11 1997/12/30 23:09:40 curt
210 * Worked on winding problem without luck, so back to calling glFrontFace()
211 * 3 times for each scenery area.
213 * Revision 1.10 1997/12/30 20:47:54 curt
214 * Integrated new event manager with subsystem initializations.
216 * Revision 1.9 1997/12/30 16:36:54 curt
217 * Merged in Durk's changes ...
219 * Revision 1.8 1997/12/19 23:35:00 curt
220 * Lot's of tweaking with sky rendering and lighting.
222 * Revision 1.7 1997/12/17 23:12:16 curt
223 * Fixed so moon and sun display lists aren't recreate periodically.
225 * Revision 1.6 1997/12/15 23:55:04 curt
226 * Add xgl wrappers for debugging.
227 * Generate terrain normals on the fly.
229 * Revision 1.5 1997/12/12 21:41:31 curt
230 * More light/material property tweaking ... still a ways off.
232 * Revision 1.4 1997/12/10 22:37:53 curt
233 * Prepended "fg" on the name of all global structures that didn't have it yet.
234 * i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
236 * Revision 1.3 1997/12/09 05:11:56 curt
237 * Working on tweaking lighting.
239 * Revision 1.2 1997/11/25 19:25:39 curt
240 * Changes to integrate Durk's moon/sun code updates + clean up.
242 * Revision 1.1 1997/10/25 03:16:11 curt
243 * Initial revision of code contributed by Durk Talsma.