/************************************************************************** * moon.c * * 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 "orbits.h" #include "moon.h" #include "../Time/fg_time.h" #include "../GLUT/views.h" /* #include "../Aircraft/aircraft.h"*/ #include "../general.h" static GLint moon; struct CelestialCoord fgCalculateMoon(struct OrbElements params, struct OrbElements sunParams, struct fgTIME t) { struct CelestialCoord result; double eccAnom, ecl, lonecl, latecl, actTime, xv, yv, v, r, xh, yh, zh, xg, yg, zg, xe, ye, ze, Ls, Lm, D, F; /* 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) ); 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); result.RightAscension = atan2(ye, xe); result.Declination = atan2(ze, sqrt(xe*xe + ye*ye)); return result; } void fgMoonInit() { struct CelestialCoord moonPos; moon = glGenLists(1); glNewList(moon, GL_COMPILE ); glBegin( GL_POINTS ); moonPos = fgCalculateMoon(pltOrbElements[1], pltOrbElements[0], cur_time_params); printf("Moon found at %f (ra), %f (dec)\n", moonPos.RightAscension, moonPos.Declination); /* give the moon a temporary color, for testing purposes */ glColor3f( 0.0, 1.0, 0.0); glVertex3f( 190000.0 * cos(moonPos.RightAscension) * cos(moonPos.Declination), 190000.0 * sin(moonPos.RightAscension) * cos(moonPos.Declination), 190000.0 * sin(moonPos.Declination) ); glEnd(); glEndList(); } void fgMoonRender() { double angle; static double warp = 0; struct VIEW *v; struct fgTIME *t; t = &cur_time_params; v = ¤t_view; glDisable( GL_FOG ); glDisable( GL_LIGHTING ); glPushMatrix(); glTranslatef( v->view_pos.x, v->view_pos.y, v->view_pos.z ); angle = t->gst * 15.0; /* 15 degrees per hour rotation */ /* warp += 1.0; */ /* warp = 15.0; */ warp = 0.0; glRotatef( (angle+warp), 0.0, 0.0, -1.0 ); printf("Rotating moon by %.2f degrees + %.2f degrees\n",angle,warp); glCallList(moon); glPopMatrix(); glEnable( GL_LIGHTING ); glEnable( GL_FOG ); } /* $Log$ /* Revision 1.1 1997/10/25 03:16:08 curt /* Initial revision of code contributed by Durk Talsma. /* */