/************************************************************************** * moon.c * Written by Durk Talsma. Started October 1997, for the flight gear project. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * $Id$ * (Log is kept at end of this file) **************************************************************************/ #include #include #include "../XGL/xgl.h" #include "orbits.h" #include "moon.h" #include "../Aircraft/aircraft.h" #include "../Include/constants.h" #include "../Include/general.h" #include "../Main/views.h" #include "../Time/fg_time.h" struct CelestialCoord moonPos; static float xMoon, yMoon, zMoon; static GLint moon; /* static GLfloat vdata[12][3] = { {-X, 0.0, Z }, { X, 0.0, Z }, {-X, 0.0, -Z}, {X, 0.0, -Z }, { 0.0, Z, X }, { 0.0, Z, -X}, {0.0, -Z, -X}, {0.0, -Z, -X}, { Z, X, 0.0 }, { -Z, X, 0.0}, {Z, -X, 0.0 }, {-Z, -X, 0.0} }; static GLuint tindices[20][3] = { {0,4,1}, {0,9,4}, {9,5,4}, {4,5,8}, {4,8,1}, {8,10,1}, {8,3,10}, {5,3,8}, {5,2,3}, {2,7,3}, {7,10,3}, {7,6,10}, {7,11,6}, {11,0,6}, {0,1,6}, {6,1,10}, {9,0,11}, {9,11,2}, {9,2,5}, {7,2,11} };*/ /* ------------------------------------------------------------- This section contains the code that generates a yellow Icosahedron. It's under development... (of Course) ______________________________________________________________*/ /* void NormalizeVector(float v[3]) { GLfloat d = sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]); if (d == 0.0) { printf("zero length vector\n"); return; } v[0] /= d; v[1] /= d; v[2] /= d; } void drawTriangle(float *v1, float *v2, float *v3) { xglBegin(GL_POLYGON); //xglBegin(GL_POINTS); xglNormal3fv(v1); xglVertex3fv(v1); xglNormal3fv(v2); xglVertex3fv(v2); xglNormal3fv(v3); xglVertex3fv(v3); xglEnd(); } void subdivide(float *v1, float *v2, float *v3, long depth) { GLfloat v12[3], v23[3], v31[3]; GLint i; if (!depth) { drawTriangle(v1, v2, v3); return; } for (i = 0; i < 3; i++) { v12[i] = (v1[i] + v2[i]); v23[i] = (v2[i] + v3[i]); v31[i] = (v3[i] + v1[i]); } NormalizeVector(v12); NormalizeVector(v23); NormalizeVector(v31); subdivide(v1, v12, v31, depth - 1); subdivide(v2, v23, v12, depth - 1); subdivide(v3, v31, v23, depth - 1); subdivide(v12, v23, v31,depth - 1); } */ /* void display(void) { int i; xglClear(GL_COLOR_BUFFER_BIT); xglPushMatrix(); xglRotatef(spin, 0.0, 0.0, 0.0); xglColor3f(1.0, 1.0, 0.0); // xglBegin(GL_LINE_LOOP); for (i = 0; i < 20; i++) { //xglVertex3fv(&vdata[tindices[i][0]][0]); //xglVertex3fv(&vdata[tindices[i][1]][0]); //xglVertex3fv(&vdata[tindices[i][2]][0]); subdivide(&vdata[tindices[i][0]][0], &vdata[tindices[i][1]][0], &vdata[tindices[i][2]][0], 3); } // xglEnd(); // xglFlush(); xglPopMatrix(); glutSwapBuffers(); } */ /* -------------------------------------------------------------- This section contains the code that calculates the actual position of the moon in the night sky. ----------------------------------------------------------------*/ struct CelestialCoord fgCalculateMoon(struct OrbElements params, struct OrbElements sunParams, struct fgTIME t) { struct CelestialCoord geocCoord, topocCoord; double eccAnom, ecl, lonecl, latecl, actTime, xv, yv, v, r, xh, yh, zh, xg, yg, zg, xe, ye, ze, Ls, Lm, D, F, mpar, gclat, rho, HA, g; struct fgAIRCRAFT *a; struct fgFLIGHT *f; a = ¤t_aircraft; f = &a->flight; /* calculate the angle between ecliptic and equatorial coordinate system */ actTime = fgCalcActTime(t); ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime); // in radians of course /* calculate the eccentric anomaly */ eccAnom = fgCalcEccAnom(params.M, params.e); /* calculate the moon's distance (d) and true anomaly (v) */ xv = params.a * ( cos(eccAnom) - params.e); yv = params.a * ( sqrt(1.0 - params.e*params.e) * sin(eccAnom)); v =atan2(yv, xv); r = sqrt(xv*xv + yv*yv); /* estimate the geocentric rectangular coordinates here */ xh = r * (cos(params.N) * cos(v + params.w) - sin(params.N) * sin(v + params.w) * cos(params.i)); yh = r * (sin(params.N) * cos(v + params.w) + cos(params.N) * sin(v + params.w) * cos(params.i)); zh = r * (sin(v + params.w) * sin(params.i)); /* calculate the ecliptic latitude and longitude here */ lonecl = atan2( yh, xh); latecl = atan2( zh, sqrt( xh*xh + yh*yh)); /* calculate a number of perturbations */ Ls = sunParams.M + sunParams.w; Lm = params.M + params.w + params.N; D = Lm - Ls; F = Lm - params.N; lonecl += fgDegToRad( - 1.274 * sin (params.M - 2*D) // the Evection + 0.658 * sin (2 * D) // the Variation - 0.186 * sin (sunParams.M) // the yearly variation - 0.059 * sin (2*params.M - 2*D) - 0.057 * sin (params.M - 2*D + sunParams.M) + 0.053 * sin (params.M + 2*D) + 0.046 * sin (2*D - sunParams.M) + 0.041 * sin (params.M - sunParams.M) - 0.035 * sin (D) // the Parallactic Equation - 0.031 * sin (params.M + sunParams.M) - 0.015 * sin (2*F - 2*D) + 0.011 * sin (params.M - 4*D) ); /* Pheeuuwwww */ latecl += fgDegToRad( - 0.173 * sin (F - 2*D) - 0.055 * sin (params.M - F - 2*D) - 0.046 * sin (params.M + F - 2*D) + 0.033 * sin (F + 2*D) + 0.017 * sin (2 * params.M + F) ); /* Yep */ r += ( - 0.58 * cos(params.M - 2*D) - 0.46 * cos(2*D) ); /* Ok! */ xg = r * cos(lonecl) * cos(latecl); yg = r * sin(lonecl) * cos(latecl); zg = r * sin(latecl); xe = xg; ye = yg * cos(ecl) - zg * sin(ecl); ze = yg * sin(ecl) + zg * cos(ecl); geocCoord.RightAscension = atan2(ye, xe); geocCoord.Declination = atan2(ze, sqrt(xe*xe + ye*ye)); /* New since 25 december 1997 */ /* Calculate the moon's topocentric position instead of it's geocentric! */ mpar = asin( 1 / r); /* calculate the moon's parrallax, i.e. the apparent size of the (equatorial) radius of the Earth, as seen from the moon */ gclat = FG_Latitude - 0.083358 * sin (2 * fgDegToRad( FG_Latitude)); rho = 0.99883 + 0.00167 * cos(2 * fgDegToRad(FG_Latitude)); if (geocCoord.RightAscension < 0) geocCoord.RightAscension += (2*FG_PI); HA = t.lst - (3.8197186 * geocCoord.RightAscension); g = atan (tan(gclat) / cos( (HA / 3.8197186))); topocCoord.RightAscension = geocCoord.RightAscension - mpar * rho * cos(gclat) * sin(HA) / cos(geocCoord.Declination); topocCoord.Declination = geocCoord.Declination - mpar * rho * sin(gclat) * sin(g - geocCoord.Declination) / sin(g); return topocCoord; } void fgMoonInit() { struct fgLIGHT *l; static int dl_exists = 0; printf("Initializing the Moon\n"); l = &cur_light_params; /* position the moon */ fgSolarSystemUpdate(&(pltOrbElements[1]), cur_time_params); moonPos = fgCalculateMoon(pltOrbElements[1], pltOrbElements[0], cur_time_params); #ifdef DEBUG printf("Moon found at %f (ra), %f (dec)\n", moonPos.RightAscension, moonPos.Declination); #endif xMoon = 60000.0 * cos(moonPos.RightAscension) * cos(moonPos.Declination); yMoon = 60000.0 * sin(moonPos.RightAscension) * cos(moonPos.Declination); zMoon = 60000.0 * sin(moonPos.Declination); if ( !dl_exists ) { dl_exists = 1; /* printf("First time through, creating moon display list\n"); */ moon = xglGenLists(1); xglNewList(moon, GL_COMPILE ); /* xglMaterialfv(GL_FRONT, GL_AMBIENT, l->scene_clear); xglMaterialfv(GL_FRONT, GL_DIFFUSE, moon_color); */ glutSolidSphere(1.0, 10, 10); xglEndList(); } } /* Draw the moon */ void fgMoonRender() { struct fgLIGHT *l; GLfloat white[4] = { 1.0, 1.0, 1.0, 1.0 }; /* printf("Rendering moon\n"); */ l = &cur_light_params; xglMaterialfv(GL_FRONT, GL_AMBIENT, l->sky_color ); xglMaterialfv(GL_FRONT, GL_DIFFUSE, white); xglPushMatrix(); xglTranslatef(xMoon, yMoon, zMoon); xglScalef(1400, 1400, 1400); xglCallList(moon); xglPopMatrix(); } /* $Log$ /* Revision 1.16 1998/01/06 01:20:24 curt /* Tweaks to help building with MSVC++ /* * Revision 1.15 1998/01/05 18:44:35 curt * Add an option to advance/decrease time from keyboard. * * Revision 1.14 1997/12/30 20:47:50 curt * Integrated new event manager with subsystem initializations. * * Revision 1.13 1997/12/30 16:41:00 curt * Added log at end of file. * */