1 /**************************************************************************
3 * Written by Durk Talsma. Started October 1997, for the flight gear project.
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License as
7 * published by the Free Software Foundation; either version 2 of the
8 * License, or (at your option) any later version.
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 * (Log is kept at end of this file)
21 **************************************************************************/
26 #include "../XGL/xgl.h"
31 #include "../Aircraft/aircraft.h"
32 #include "../Include/general.h"
33 #include "../Main/views.h"
34 #include "../Time/fg_time.h"
36 struct CelestialCoord moonPos;
38 static float xMoon, yMoon, zMoon;
42 static GLfloat vdata[12][3] =
44 {-X, 0.0, Z }, { X, 0.0, Z }, {-X, 0.0, -Z}, {X, 0.0, -Z },
45 { 0.0, Z, X }, { 0.0, Z, -X}, {0.0, -Z, -X}, {0.0, -Z, -X},
46 { Z, X, 0.0 }, { -Z, X, 0.0}, {Z, -X, 0.0 }, {-Z, -X, 0.0}
49 static GLuint tindices[20][3] =
51 {0,4,1}, {0,9,4}, {9,5,4}, {4,5,8}, {4,8,1},
52 {8,10,1}, {8,3,10}, {5,3,8}, {5,2,3}, {2,7,3},
53 {7,10,3}, {7,6,10}, {7,11,6}, {11,0,6}, {0,1,6},
54 {6,1,10}, {9,0,11}, {9,11,2}, {9,2,5}, {7,2,11}
57 /* -------------------------------------------------------------
58 This section contains the code that generates a yellow
59 Icosahedron. It's under development... (of Course)
60 ______________________________________________________________*/
62 void NormalizeVector(float v[3])
64 GLfloat d = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
67 printf("zero length vector\n");
75 void drawTriangle(float *v1, float *v2, float *v3)
78 //xglBegin(GL_POINTS);
88 void subdivide(float *v1, float *v2, float *v3, long depth)
90 GLfloat v12[3], v23[3], v31[3];
95 drawTriangle(v1, v2, v3);
98 for (i = 0; i < 3; i++)
100 v12[i] = (v1[i] + v2[i]);
101 v23[i] = (v2[i] + v3[i]);
102 v31[i] = (v3[i] + v1[i]);
104 NormalizeVector(v12);
105 NormalizeVector(v23);
106 NormalizeVector(v31);
107 subdivide(v1, v12, v31, depth - 1);
108 subdivide(v2, v23, v12, depth - 1);
109 subdivide(v3, v31, v23, depth - 1);
110 subdivide(v12, v23, v31,depth - 1);
117 xglClear(GL_COLOR_BUFFER_BIT);
119 xglRotatef(spin, 0.0, 0.0, 0.0);
120 xglColor3f(1.0, 1.0, 0.0);
121 // xglBegin(GL_LINE_LOOP);
122 for (i = 0; i < 20; i++)
125 //xglVertex3fv(&vdata[tindices[i][0]][0]);
126 //xglVertex3fv(&vdata[tindices[i][1]][0]);
127 //xglVertex3fv(&vdata[tindices[i][2]][0]);
129 subdivide(&vdata[tindices[i][0]][0],
130 &vdata[tindices[i][1]][0],
131 &vdata[tindices[i][2]][0], 3);
141 /* --------------------------------------------------------------
143 This section contains the code that calculates the actual
144 position of the moon in the night sky.
146 ----------------------------------------------------------------*/
148 struct CelestialCoord fgCalculateMoon(struct OrbElements params,
149 struct OrbElements sunParams,
152 struct CelestialCoord
153 geocCoord, topocCoord;
157 eccAnom, ecl, lonecl, latecl, actTime,
158 xv, yv, v, r, xh, yh, zh, xg, yg, zg, xe, ye, ze,
159 Ls, Lm, D, F, mpar, gclat, rho, HA, g;
161 struct fgAIRCRAFT *a;
164 a = ¤t_aircraft;
167 /* calculate the angle between ecliptic and equatorial coordinate system */
168 actTime = fgCalcActTime(t);
169 ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime); // in radians of course
171 /* calculate the eccentric anomaly */
172 eccAnom = fgCalcEccAnom(params.M, params.e);
174 /* calculate the moon's distance (d) and true anomaly (v) */
175 xv = params.a * ( cos(eccAnom) - params.e);
176 yv = params.a * ( sqrt(1.0 - params.e*params.e) * sin(eccAnom));
178 r = sqrt(xv*xv + yv*yv);
180 /* estimate the geocentric rectangular coordinates here */
181 xh = r * (cos(params.N) * cos(v + params.w) - sin(params.N) * sin(v + params.w) * cos(params.i));
182 yh = r * (sin(params.N) * cos(v + params.w) + cos(params.N) * sin(v + params.w) * cos(params.i));
183 zh = r * (sin(v + params.w) * sin(params.i));
185 /* calculate the ecliptic latitude and longitude here */
186 lonecl = atan2( yh, xh);
187 latecl = atan2( zh, sqrt( xh*xh + yh*yh));
189 /* calculate a number of perturbations */
190 Ls = sunParams.M + sunParams.w;
191 Lm = params.M + params.w + params.N;
195 lonecl += fgDegToRad(
196 - 1.274 * sin (params.M - 2*D) // the Evection
197 + 0.658 * sin (2 * D) // the Variation
198 - 0.186 * sin (sunParams.M) // the yearly variation
199 - 0.059 * sin (2*params.M - 2*D)
200 - 0.057 * sin (params.M - 2*D + sunParams.M)
201 + 0.053 * sin (params.M + 2*D)
202 + 0.046 * sin (2*D - sunParams.M)
203 + 0.041 * sin (params.M - sunParams.M)
204 - 0.035 * sin (D) // the Parallactic Equation
205 - 0.031 * sin (params.M + sunParams.M)
206 - 0.015 * sin (2*F - 2*D)
207 + 0.011 * sin (params.M - 4*D)
209 latecl += fgDegToRad(
210 - 0.173 * sin (F - 2*D)
211 - 0.055 * sin (params.M - F - 2*D)
212 - 0.046 * sin (params.M + F - 2*D)
213 + 0.033 * sin (F + 2*D)
214 + 0.017 * sin (2 * params.M + F)
218 - 0.58 * cos(params.M - 2*D)
222 xg = r * cos(lonecl) * cos(latecl);
223 yg = r * sin(lonecl) * cos(latecl);
224 zg = r * sin(latecl);
227 ye = yg * cos(ecl) - zg * sin(ecl);
228 ze = yg * sin(ecl) + zg * cos(ecl);
233 geocCoord.RightAscension = atan2(ye, xe);
234 geocCoord.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
236 /* New since 25 december 1997 */
237 /* Calculate the moon's topocentric position instead of it's geocentric! */
239 mpar = asin( 1 / r); /* calculate the moon's parrallax, i.e. the apparent size of the
240 (equatorial) radius of the Earth, as seen from the moon */
241 gclat = FG_Latitude - 0.083358 * sin (2 * fgDegToRad( FG_Latitude));
242 rho = 0.99883 + 0.00167 * cos(2 * fgDegToRad(FG_Latitude));
244 if (geocCoord.RightAscension < 0)
245 geocCoord.RightAscension += (2*M_PI);
247 HA = t.lst - (3.8197186 * geocCoord.RightAscension);
249 g = atan (tan(gclat) / cos( (HA / 3.8197186)));
253 topocCoord.RightAscension = geocCoord.RightAscension - mpar * rho * cos(gclat) * sin(HA) / cos(geocCoord.Declination);
254 topocCoord.Declination = geocCoord.Declination - mpar * rho * sin(gclat) * sin(g - geocCoord.Declination) / sin(g);
261 static int dl_exists = 0;
263 l = &cur_light_params;
265 /* position the moon */
266 fgSolarSystemUpdate(&(pltOrbElements[1]), cur_time_params);
267 moonPos = fgCalculateMoon(pltOrbElements[1], pltOrbElements[0],
270 printf("Moon found at %f (ra), %f (dec)\n", moonPos.RightAscension,
271 moonPos.Declination);
277 /* printf("First time through, creating moon display list\n"); */
279 moon = xglGenLists(1);
280 xglNewList(moon, GL_COMPILE );
282 /* xglMaterialfv(GL_FRONT, GL_AMBIENT, l->scene_clear);
283 xglMaterialfv(GL_FRONT, GL_DIFFUSE, moon_color); */
286 xMoon = 60000.0 * cos(moonPos.RightAscension) *
287 cos(moonPos.Declination);
288 yMoon = 60000.0 * sin(moonPos.RightAscension) *
289 cos(moonPos.Declination);
290 zMoon = 60000.0 * sin(moonPos.Declination);
292 glutSolidSphere(1.0, 10, 10);
300 void fgMoonRender() {
302 GLfloat white[4] = { 1.0, 1.0, 1.0, 1.0 };
304 l = &cur_light_params;
306 xglMaterialfv(GL_FRONT, GL_AMBIENT, l->sky_color );
307 xglMaterialfv(GL_FRONT, GL_DIFFUSE, white);
310 xglTranslatef(xMoon, yMoon, zMoon);
311 xglScalef(1400, 1400, 1400);