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 <Time/fg_time.h>
29 #include <Main/views.h>
30 #include <Astro/orbits.h>
31 #include <Astro/sun.h>
32 #include <Main/fg_debug.h>
33 #include <Include/fg_constants.h>
37 static struct CelestialCoord sunPos;
39 float xSun, ySun, zSun;
41 struct SunPos fgCalcSunPos(struct OrbElements params)
49 /* calculate the eccentric anomaly */
50 EccAnom = fgCalcEccAnom(params.M, params.e);
52 /* calculate the Suns distance (r) and its true anomaly (v) */
53 xv = cos(EccAnom) - params.e;
54 yv = sqrt(1.0 - params.e*params.e) * sin(EccAnom);
56 r = sqrt(xv*xv + yv*yv);
58 /* calculate the the Sun's true longitude (lonsun) */
59 lonSun = v + params.w;
61 /* convert true longitude and distance to ecliptic rectangular geocentric
62 coordinates (xs, ys) */
63 solarPosition.xs = r * cos(lonSun);
64 solarPosition.ys = r * sin(lonSun);
65 solarPosition.dist = r;
70 struct CelestialCoord fgCalculateSun(struct OrbElements params, struct fgTIME t)
77 xe, ye, ze, ecl, actTime;
79 /* calculate the angle between ecliptic and equatorial coordinate system */
80 actTime = fgCalcActTime(t);
81 ecl = DEG_TO_RAD * (23.4393 - 3.563E-7 * actTime); // Angle now in Rads
83 /* calculate the sun's ecliptic position */
84 SolarPosition = fgCalcSunPos(params);
86 /* convert ecliptic coordinates to equatorial rectangular geocentric coordinates */
87 xe = SolarPosition.xs;
88 ye = SolarPosition.ys * cos(ecl);
89 ze = SolarPosition.ys * sin(ecl);
91 /* and finally... Calulate Right Ascention and Declination */
92 result.RightAscension = atan2( ye, xe);
93 result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
98 /* Initialize the Sun */
99 void fgSunInit( void ) {
104 /* GLfloat color[4] = { 1.00, 1.00, 1.00, 1.00 }; */
105 double x_2, x_4, x_8, x_10;
109 l = &cur_light_params;
110 t = &cur_time_params;
113 fgPrintf( FG_ASTRO, FG_INFO, " Initializing the Sun\n");
115 fgSolarSystemUpdate(&(pltOrbElements[0]), cur_time_params);
116 sunPos = fgCalculateSun(pltOrbElements[0], cur_time_params);
117 fgPrintf( FG_ASTRO, FG_INFO,
118 "Sun found at %f (ra), %f (dec)\n",
119 sunPos.RightAscension, sunPos.Declination);
121 xSun = 60000.0 * cos(sunPos.RightAscension) * cos(sunPos.Declination);
122 ySun = 60000.0 * sin(sunPos.RightAscension) * cos(sunPos.Declination);
123 zSun = 60000.0 * sin(sunPos.Declination);
127 xglDeleteLists(sun_obj, 1);
130 /* printf("First time through, creating sun display list\n"); */
132 sun_obj = xglGenLists(1);
133 xglNewList(sun_obj, GL_COMPILE );
136 t = &cur_time_params;
138 l = &cur_light_params;
140 x_2 = l->sun_angle * l->sun_angle;
145 ambient = (0.4 * pow(1.1, -x_10 / 30.0));
146 if ( ambient < 0.3 ) ambient = 0.3;
147 if ( ambient > 1.0 ) ambient = 1.0;
149 amb[0] = 0.00 + ((ambient * 6.0) - 1.0); /* minimum val = 0.8 */
150 amb[1] = 0.00 + ((ambient * 11.0) - 3.0); /* minimum val = 0.3 */
151 amb[2] = 0.00 + ((ambient * 12.0) - 3.6); /* minimum val = 0.0 */
154 if (amb[0] > 1.0) amb[0] = 1.0;
155 if (amb[1] > 1.0) amb[1] = 1.0;
156 if (amb[2] > 1.0) amb[2] = 1.0;
158 fgPrintf( FG_ASTRO, FG_DEBUG,
159 "Color of the sun: %f, %f, %f\n"
160 "Ambient value : %f\n"
162 amb[0], amb[1], amb[2], ambient, l->sun_angle);
164 /* set lighting parameters */
165 /*xglLightfv(GL_LIGHT0, GL_AMBIENT, color );
166 xglLightfv(GL_LIGHT0, GL_DIFFUSE, color );
167 xglMaterialfv(GL_FRONT, GL_AMBIENT, amb);
168 xglMaterialfv(GL_FRONT, GL_DIFFUSE, diff);
169 xglMaterialfv(GL_FRONT, GL_SHININESS, diff);
170 xglMaterialfv(GL_FRONT, GL_EMISSION, diff);
171 xglMaterialfv(GL_FRONT, GL_SPECULAR, diff); */
173 /* xglDisable( GL_LIGHTING ); */
176 xglTranslatef(xSun, ySun, zSun);
177 xglScalef(1400, 1400, 1400);
179 /*xglColor3f(0.85, 0.65, 0.05);*/
180 xglColor3f(amb[0], amb[1], amb[2]);
181 glutSolidSphere(1.0, 10, 10);
185 /* xglEnable( GL_LIGHTING ); */
192 void fgSunRender( void ) {
193 xglCallList(sun_obj);
198 /* Revision 1.5 1998/02/02 20:53:24 curt
201 * Revision 1.4 1998/01/27 00:47:50 curt
202 * Incorporated Paul Bleisch's <bleisch@chromatic.com> new debug message
203 * system and commandline/config file processing code.
205 * Revision 1.3 1998/01/19 19:27:00 curt
206 * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
207 * This should simplify things tremendously.
209 * Revision 1.2 1998/01/19 18:40:18 curt
210 * Tons of little changes to clean up the code and to remove fatal errors
211 * when building with the c++ compiler.
213 * Revision 1.1 1998/01/07 03:16:20 curt
214 * Moved from .../Src/Scenery/ to .../Src/Astro/
216 * Revision 1.12 1998/01/05 18:44:36 curt
217 * Add an option to advance/decrease time from keyboard.
219 * Revision 1.11 1997/12/30 23:09:40 curt
220 * Worked on winding problem without luck, so back to calling glFrontFace()
221 * 3 times for each scenery area.
223 * Revision 1.10 1997/12/30 20:47:54 curt
224 * Integrated new event manager with subsystem initializations.
226 * Revision 1.9 1997/12/30 16:36:54 curt
227 * Merged in Durk's changes ...
229 * Revision 1.8 1997/12/19 23:35:00 curt
230 * Lot's of tweaking with sky rendering and lighting.
232 * Revision 1.7 1997/12/17 23:12:16 curt
233 * Fixed so moon and sun display lists aren't recreate periodically.
235 * Revision 1.6 1997/12/15 23:55:04 curt
236 * Add xgl wrappers for debugging.
237 * Generate terrain normals on the fly.
239 * Revision 1.5 1997/12/12 21:41:31 curt
240 * More light/material property tweaking ... still a ways off.
242 * Revision 1.4 1997/12/10 22:37:53 curt
243 * Prepended "fg" on the name of all global structures that didn't have it yet.
244 * i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
246 * Revision 1.3 1997/12/09 05:11:56 curt
247 * Working on tweaking lighting.
249 * Revision 1.2 1997/11/25 19:25:39 curt
250 * Changes to integrate Durk's moon/sun code updates + clean up.
252 * Revision 1.1 1997/10/25 03:16:11 curt
253 * Initial revision of code contributed by Durk Talsma.