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>
36 static struct CelestialCoord sunPos;
38 float xSun, ySun, zSun;
40 struct SunPos fgCalcSunPos(struct OrbElements params)
48 /* calculate the eccentric anomaly */
49 EccAnom = fgCalcEccAnom(params.M, params.e);
51 /* calculate the Suns distance (r) and its true anomaly (v) */
52 xv = cos(EccAnom) - params.e;
53 yv = sqrt(1.0 - params.e*params.e) * sin(EccAnom);
55 r = sqrt(xv*xv + yv*yv);
57 /* calculate the the Sun's true longitude (lonsun) */
58 lonSun = v + params.w;
60 /* convert true longitude and distance to ecliptic rectangular geocentric
61 coordinates (xs, ys) */
62 solarPosition.xs = r * cos(lonSun);
63 solarPosition.ys = r * sin(lonSun);
64 solarPosition.dist = r;
69 struct CelestialCoord fgCalculateSun(struct OrbElements params, struct fgTIME t)
76 xe, ye, ze, ecl, actTime;
78 /* calculate the angle between ecliptic and equatorial coordinate system */
79 actTime = fgCalcActTime(t);
80 ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime); // Angle now in Rads
82 /* calculate the sun's ecliptic position */
83 SolarPosition = fgCalcSunPos(params);
85 /* convert ecliptic coordinates to equatorial rectangular geocentric coordinates */
86 xe = SolarPosition.xs;
87 ye = SolarPosition.ys * cos(ecl);
88 ze = SolarPosition.ys * sin(ecl);
90 /* and finally... Calulate Right Ascention and Declination */
91 result.RightAscension = atan2( ye, xe);
92 result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
97 /* Initialize the Sun */
98 void fgSunInit( void ) {
99 static int dl_exists = 0;
101 fgPrintf( FG_ASTRO, FG_INFO, " Initializing the Sun\n");
103 fgSolarSystemUpdate(&(pltOrbElements[0]), cur_time_params);
104 sunPos = fgCalculateSun(pltOrbElements[0], cur_time_params);
106 fgPrintf( FG_ASTRO, FG_INFO,
107 "Sun found at %f (ra), %f (dec)\n",
108 sunPos.RightAscension, sunPos.Declination);
111 xSun = 60000.0 * cos(sunPos.RightAscension) * cos(sunPos.Declination);
112 ySun = 60000.0 * sin(sunPos.RightAscension) * cos(sunPos.Declination);
113 zSun = 60000.0 * sin(sunPos.Declination);
118 /* printf("First time through, creating sun display list\n"); */
120 sun_obj = xglGenLists(1);
121 xglNewList(sun_obj, GL_COMPILE );
123 glutSolidSphere(1.0, 10, 10);
131 void fgSunRender( void ) {
135 /* GLfloat color[4] = { 0.85, 0.65, 0.05, 1.0 }; */
136 GLfloat color[4] = { 1.00, 1.00, 1.00, 1.00 };
137 double x_2, x_4, x_8, x_10;
139 GLfloat amb[3], diff[3];
142 t = &cur_time_params;
144 l = &cur_light_params;
146 x_2 = l->sun_angle * l->sun_angle;
151 ambient = (0.4 * pow(1.1, -x_10 / 30.0));
152 if ( ambient < 0.3 ) ambient = 0.3;
153 if ( ambient > 1.0 ) ambient = 1.0;
155 amb[0] = 0.50 + ((ambient * 6.66) - 1.6);
156 amb[1] = 0.00 + ((ambient * 6.66) - 1.6);
157 amb[2] = 0.00 + ((ambient * 6.66) - 1.6);
160 fgPrintf( FG_ASTRO, FG_INFO,
161 "Color of the sun: %f, %f, %f\n"
162 "Ambient value : %f\n"
163 "Sun Angle : %f\n" , amb[0], amb[1], amb[2], ambient, t->sun_angle);
170 /* set lighting parameters */
171 xglLightfv(GL_LIGHT0, GL_AMBIENT, color );
172 xglLightfv(GL_LIGHT0, GL_DIFFUSE, color );
173 xglMaterialfv(GL_FRONT, GL_AMBIENT, amb);
174 xglMaterialfv(GL_FRONT, GL_DIFFUSE, diff);
175 xglMaterialfv(GL_FRONT, GL_SHININESS, diff);
176 xglMaterialfv(GL_FRONT, GL_EMISSION, diff);
177 xglMaterialfv(GL_FRONT, GL_SPECULAR, diff);
179 /* xglDisable( GL_LIGHTING ); */
182 xglTranslatef(xSun, ySun, zSun);
183 xglScalef(1400, 1400, 1400);
185 xglColor3f(0.85, 0.65, 0.05);
187 xglCallList(sun_obj);
191 /* xglEnable( GL_LIGHTING ); */
196 /* Revision 1.4 1998/01/27 00:47:50 curt
197 /* Incorporated Paul Bleisch's <bleisch@chromatic.com> new debug message
198 /* system and commandline/config file processing code.
200 * Revision 1.3 1998/01/19 19:27:00 curt
201 * Merged in make system changes from Bob Kuehne <rpk@sgi.com>
202 * This should simplify things tremendously.
204 * Revision 1.2 1998/01/19 18:40:18 curt
205 * Tons of little changes to clean up the code and to remove fatal errors
206 * when building with the c++ compiler.
208 * Revision 1.1 1998/01/07 03:16:20 curt
209 * Moved from .../Src/Scenery/ to .../Src/Astro/
211 * Revision 1.12 1998/01/05 18:44:36 curt
212 * Add an option to advance/decrease time from keyboard.
214 * Revision 1.11 1997/12/30 23:09:40 curt
215 * Worked on winding problem without luck, so back to calling glFrontFace()
216 * 3 times for each scenery area.
218 * Revision 1.10 1997/12/30 20:47:54 curt
219 * Integrated new event manager with subsystem initializations.
221 * Revision 1.9 1997/12/30 16:36:54 curt
222 * Merged in Durk's changes ...
224 * Revision 1.8 1997/12/19 23:35:00 curt
225 * Lot's of tweaking with sky rendering and lighting.
227 * Revision 1.7 1997/12/17 23:12:16 curt
228 * Fixed so moon and sun display lists aren't recreate periodically.
230 * Revision 1.6 1997/12/15 23:55:04 curt
231 * Add xgl wrappers for debugging.
232 * Generate terrain normals on the fly.
234 * Revision 1.5 1997/12/12 21:41:31 curt
235 * More light/material property tweaking ... still a ways off.
237 * Revision 1.4 1997/12/10 22:37:53 curt
238 * Prepended "fg" on the name of all global structures that didn't have it yet.
239 * i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
241 * Revision 1.3 1997/12/09 05:11:56 curt
242 * Working on tweaking lighting.
244 * Revision 1.2 1997/11/25 19:25:39 curt
245 * Changes to integrate Durk's moon/sun code updates + clean up.
247 * Revision 1.1 1997/10/25 03:16:11 curt
248 * Initial revision of code contributed by Durk Talsma.