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 **************************************************************************/
26 #include "../XGL/xgl.h"
28 #include "../Time/fg_time.h"
29 #include "../Main/views.h"
35 static struct CelestialCoord sunPos;
37 float xSun, ySun, zSun;
39 struct SunPos fgCalcSunPos(struct OrbElements params)
47 /* calculate the eccentric anomaly */
48 EccAnom = fgCalcEccAnom(params.M, params.e);
50 /* calculate the Suns distance (r) and its true anomaly (v) */
51 xv = cos(EccAnom) - params.e;
52 yv = sqrt(1.0 - params.e*params.e) * sin(EccAnom);
54 r = sqrt(xv*xv + yv*yv);
56 /* calculate the the Sun's true longitude (lonsun) */
57 lonSun = v + params.w;
59 /* convert true longitude and distance to ecliptic rectangular geocentric
60 coordinates (xs, ys) */
61 solarPosition.xs = r * cos(lonSun);
62 solarPosition.ys = r * sin(lonSun);
63 solarPosition.dist = r;
68 struct CelestialCoord fgCalculateSun(struct OrbElements params, struct fgTIME t)
75 xe, ye, ze, ecl, actTime;
77 /* calculate the angle between ecliptic and equatorial coordinate system */
78 actTime = fgCalcActTime(t);
79 ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime); // Angle now in Rads
81 /* calculate the sun's ecliptic position */
82 SolarPosition = fgCalcSunPos(params);
84 /* convert ecliptic coordinates to equatorial rectangular geocentric coordinates */
85 xe = SolarPosition.xs;
86 ye = SolarPosition.ys * cos(ecl);
87 ze = SolarPosition.ys * sin(ecl);
89 /* and finally... Calulate Right Ascention and Declination */
90 result.RightAscension = atan2( ye, xe);
91 result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
96 /* Initialize the Sun */
98 static int dl_exists = 0;
100 printf(" Initializing the Sun\n");
102 fgSolarSystemUpdate(&(pltOrbElements[0]), cur_time_params);
103 sunPos = fgCalculateSun(pltOrbElements[0], cur_time_params);
105 printf("Sun found at %f (ra), %f (dec)\n", sunPos.RightAscension,
109 xSun = 60000.0 * cos(sunPos.RightAscension) * cos(sunPos.Declination);
110 ySun = 60000.0 * sin(sunPos.RightAscension) * cos(sunPos.Declination);
111 zSun = 60000.0 * sin(sunPos.Declination);
116 /* printf("First time through, creating sun display list\n"); */
118 sun_obj = xglGenLists(1);
119 xglNewList(sun_obj, GL_COMPILE );
121 glutSolidSphere(1.0, 10, 10);
133 /* GLfloat color[4] = { 0.85, 0.65, 0.05, 1.0 }; */
134 GLfloat color[4] = { 1.00, 1.00, 1.00, 1.00 };
135 double x_2, x_4, x_8, x_10;
137 GLfloat amb[3], diff[3];
140 t = &cur_time_params;
142 l = &cur_light_params;
144 x_2 = l->sun_angle * l->sun_angle;
149 ambient = (0.4 * pow(1.1, -x_10 / 30.0));
150 if ( ambient < 0.3 ) ambient = 0.3;
151 if ( ambient > 1.0 ) ambient = 1.0;
153 amb[0] = 0.50 + ((ambient * 6.66) - 1.6);
154 amb[1] = 0.00 + ((ambient * 6.66) - 1.6);
155 amb[2] = 0.00 + ((ambient * 6.66) - 1.6);
158 printf("Color of the sun: %f, %f, %f\n"
159 "Ambient value : %f\n"
160 "Sun Angle : %f\n" , amb[0], amb[1], amb[2], ambient, t->sun_angle);
167 /* set lighting parameters */
168 xglLightfv(GL_LIGHT0, GL_AMBIENT, color );
169 xglLightfv(GL_LIGHT0, GL_DIFFUSE, color );
170 xglMaterialfv(GL_FRONT, GL_AMBIENT, amb);
171 xglMaterialfv(GL_FRONT, GL_DIFFUSE, diff);
172 xglMaterialfv(GL_FRONT, GL_SHININESS, diff);
173 xglMaterialfv(GL_FRONT, GL_EMISSION, diff);
174 xglMaterialfv(GL_FRONT, GL_SPECULAR, diff);
176 /* xglDisable( GL_LIGHTING ); */
179 xglTranslatef(xSun, ySun, zSun);
180 xglScalef(1400, 1400, 1400);
182 xglColor3f(0.85, 0.65, 0.05);
184 xglCallList(sun_obj);
188 /* xglEnable( GL_LIGHTING ); */
193 /* Revision 1.1 1998/01/07 03:16:20 curt
194 /* Moved from .../Src/Scenery/ to .../Src/Astro/
196 * Revision 1.12 1998/01/05 18:44:36 curt
197 * Add an option to advance/decrease time from keyboard.
199 * Revision 1.11 1997/12/30 23:09:40 curt
200 * Worked on winding problem without luck, so back to calling glFrontFace()
201 * 3 times for each scenery area.
203 * Revision 1.10 1997/12/30 20:47:54 curt
204 * Integrated new event manager with subsystem initializations.
206 * Revision 1.9 1997/12/30 16:36:54 curt
207 * Merged in Durk's changes ...
209 * Revision 1.8 1997/12/19 23:35:00 curt
210 * Lot's of tweaking with sky rendering and lighting.
212 * Revision 1.7 1997/12/17 23:12:16 curt
213 * Fixed so moon and sun display lists aren't recreate periodically.
215 * Revision 1.6 1997/12/15 23:55:04 curt
216 * Add xgl wrappers for debugging.
217 * Generate terrain normals on the fly.
219 * Revision 1.5 1997/12/12 21:41:31 curt
220 * More light/material property tweaking ... still a ways off.
222 * Revision 1.4 1997/12/10 22:37:53 curt
223 * Prepended "fg" on the name of all global structures that didn't have it yet.
224 * i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
226 * Revision 1.3 1997/12/09 05:11:56 curt
227 * Working on tweaking lighting.
229 * Revision 1.2 1997/11/25 19:25:39 curt
230 * Changes to integrate Durk's moon/sun code updates + clean up.
232 * Revision 1.1 1997/10/25 03:16:11 curt
233 * Initial revision of code contributed by Durk Talsma.