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);
67 struct CelestialCoord fgCalculateSun(struct OrbElements params, struct fgTIME t)
74 xe, ye, ze, ecl, actTime;
76 /* calculate the angle between ecliptic and equatorial coordinate system */
77 actTime = fgCalcActTime(t);
78 ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime); // Angle now in Rads
80 /* calculate the sun's ecliptic position */
81 SolarPosition = fgCalcSunPos(params);
83 /* convert ecliptic coordinates to equatorial rectangular geocentric coordinates */
84 xe = SolarPosition.xs;
85 ye = SolarPosition.ys * cos(ecl);
86 ze = SolarPosition.ys * sin(ecl);
88 /* and finally... Calulate Right Ascention and Declination */
89 result.RightAscension = atan2( ye, xe);
90 result.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
95 /* Initialize the Sun */
97 static int dl_exists = 0;
99 fgSolarSystemUpdate(&(pltOrbElements[0]), cur_time_params);
100 sunPos = fgCalculateSun(pltOrbElements[0], cur_time_params);
102 printf("Sun found at %f (ra), %f (dec)\n", sunPos.RightAscension,
109 /* printf("First time through, creating sun display list\n"); */
111 sun_obj = xglGenLists(1);
112 xglNewList(sun_obj, GL_COMPILE );
114 xSun = 60000.0 * cos(sunPos.RightAscension) * cos(sunPos.Declination);
115 ySun = 60000.0 * sin(sunPos.RightAscension) * cos(sunPos.Declination);
116 zSun = 60000.0 * sin(sunPos.Declination);
118 glutSolidSphere(1.0, 10, 10);
129 GLfloat color[4] = { 0.85, 0.65, 0.05, 1.0 };
130 /* double x_2, x_4, x_8, x_10; */
131 /* GLfloat ambient; */
132 /* GLfloat amb[3], diff[3]; */
135 t = &cur_time_params;
138 /* x_2 = t->sun_angle * t->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;
146 amb[0] = 0.50 + ((ambient * 6.66) - 1.6);
147 amb[1] = 0.00 + ((ambient * 6.66) - 1.6);
148 amb[2] = 0.00 + ((ambient * 6.66) - 1.6);
151 printf("Color of the sun: %f, %f, %f\n"
152 "Ambient value : %f\n"
153 "Sun Angle : %f\n" , amb[0], amb[1], amb[2], ambient, t->sun_angle);
160 /* set lighting parameters */
161 /* xglLightfv(GL_LIGHT0, GL_AMBIENT, color );
162 xglLightfv(GL_LIGHT0, GL_DIFFUSE, color );
163 xglMaterialfv(GL_FRONT, GL_AMBIENT, amb);
164 xglMaterialfv(GL_FRONT, GL_DIFFUSE, diff); */
166 xglDisable( GL_LIGHTING );
169 xglTranslatef(xSun, ySun, zSun);
170 xglScalef(1400, 1400, 1400);
172 xglColor3f(0.85, 0.65, 0.05);
174 /* xglColor3fv( color ); */
175 /* xglutSolidSphere(1.0, 25, 25); */
176 xglCallList(sun_obj);
180 xglEnable( GL_LIGHTING );
185 /* Revision 1.7 1997/12/17 23:12:16 curt
186 /* Fixed so moon and sun display lists aren't recreate periodically.
188 * Revision 1.6 1997/12/15 23:55:04 curt
189 * Add xgl wrappers for debugging.
190 * Generate terrain normals on the fly.
192 * Revision 1.5 1997/12/12 21:41:31 curt
193 * More light/material property tweaking ... still a ways off.
195 * Revision 1.4 1997/12/10 22:37:53 curt
196 * Prepended "fg" on the name of all global structures that didn't have it yet.
197 * i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
199 * Revision 1.3 1997/12/09 05:11:56 curt
200 * Working on tweaking lighting.
202 * Revision 1.2 1997/11/25 19:25:39 curt
203 * Changes to integrate Durk's moon/sun code updates + clean up.
205 * Revision 1.1 1997/10/25 03:16:11 curt
206 * Initial revision of code contributed by Durk Talsma.