/************************************************************************** * moon.cxx * Written by Durk Talsma. Originally started October 1997, for distribution * with the FlightGear project. Version 2 was written in August and * September 1998. This code is based upon algorithms and data kindly * provided by Mr. Paul Schlyter. (pausch@saaf.se). * * 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 "moon.hxx" #include #include static GLuint moon_texid; static GLubyte *moon_texbuf; /************************************************************************* * Moon::Moon(fgTIME *t) * Public constructor for class Moon. Initializes the orbital elements and * sets up the moon texture. * Argument: The current time. * the hard coded orbital elements for Moon are passed to * CelestialBody::CelestialBody(); ************************************************************************/ Moon::Moon(fgTIME *t) : CelestialBody(125.1228, -0.0529538083, 5.1454, 0.00000, 318.0634, 0.1643573223, 60.266600, 0.000000, 0.054900, 0.000000, 115.3654, 13.0649929509, t) { string tpath, fg_tpath; int width, height; fgPrintf( FG_GENERAL, FG_INFO, "Initializing Moon Texture\n"); #ifdef GL_VERSION_1_1 xglGenTextures(1, &moon_texid); xglBindTexture(GL_TEXTURE_2D, moon_texid); #elif GL_EXT_texture_object xglGenTexturesEXT(1, &moon_texid); xglBindTextureEXT(GL_TEXTURE_2D, moon_texid); #else # error port me #endif glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); // load in the texture data tpath = current_options.get_fg_root() + "/Textures/" + "moon.rgb"; if ( (moon_texbuf = read_rgb_texture(tpath.c_str(), &width, &height)) == NULL ) { // Try compressed fg_tpath = tpath + ".gz"; if ( (moon_texbuf = read_rgb_texture(fg_tpath.c_str(), &width, &height)) == NULL ) { fgPrintf( FG_GENERAL, FG_EXIT, "Error in loading moon texture %s\n", tpath.c_str() ); exit(1); } } glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, 256, 256, 0, GL_RGB, GL_UNSIGNED_BYTE, moon_texbuf); } /***************************************************************************** * void Moon::updatePosition(fgTIME *t, Star *ourSun) * this member function calculates the actual topocentric position (i.e.) * the position of the moon as seen from the current position on the surface * of the moon. ****************************************************************************/ void Moon::updatePosition(fgTIME *t, Star *ourSun) { 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, geoRa, geoDec; fgAIRCRAFT *air; fgFLIGHT *f; air = ¤t_aircraft; f = air->flight; updateOrbElements(t); actTime = fgCalcActTime(t); // calculate the angle between ecliptic and equatorial coordinate system // in Radians ecl = ((DEG_TO_RAD * 23.4393) - (DEG_TO_RAD * 3.563E-7) * actTime); eccAnom = fgCalcEccAnom(M, e); // Calculate the eccentric anomaly xv = a * (cos(eccAnom) - e); yv = a * (sqrt(1.0 - e*e) * sin(eccAnom)); v = atan2(yv, xv); // the moon's true anomaly r = sqrt (xv*xv + yv*yv); // and its distance // estimate the geocentric rectangular coordinates here xh = r * (cos(N) * cos (v+w) - sin (N) * sin(v+w) * cos(i)); yh = r * (sin(N) * cos (v+w) + cos (N) * sin(v+w) * cos(i)); zh = r * (sin(v+w) * sin(i)); // calculate the ecliptic latitude and longitude here lonecl = atan2 (yh, xh); latecl = atan2(zh, sqrt(xh*xh + yh*yh)); /* Calculate a number of perturbatioin, i.e. disturbances caused by the * gravitational infuence of the sun and the other major planets. * The largest of these even have a name */ Ls = ourSun->getM() + ourSun->getw(); Lm = M + w + N; D = Lm - Ls; F = Lm - N; lonecl += DEG_TO_RAD * (-1.274 * sin (M - 2*D) +0.658 * sin (2*D) -0.186 * sin(ourSun->getM()) -0.059 * sin(2*M - 2*D) -0.057 * sin(M - 2*D + ourSun->getM()) +0.053 * sin(M + 2*D) +0.046 * sin(2*D - ourSun->getM()) +0.041 * sin(M - ourSun->getM()) -0.035 * sin(D) -0.031 * sin(M + ourSun->getM()) -0.015 * sin(2*F - 2*D) +0.011 * sin(M - 4*D) ); latecl += DEG_TO_RAD * (-0.173 * sin(F-2*D) -0.055 * sin(M - F - 2*D) -0.046 * sin(M + F - 2*D) +0.033 * sin(F + 2*D) +0.017 * sin(2*M + F) ); r += (-0.58 * cos(M - 2*D) -0.46 * cos(2*D) ); fgPrintf(FG_GENERAL, FG_INFO, "Running moon update\n"); 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); geoRa = atan2(ye, xe); geoDec = atan2(ze, sqrt(xe*xe + ye*ye)); // Given the moon's geocentric ra and dec, calculate its // topocentric ra and dec. i.e. the position as seen from the // surface of the earth, instead of the center of the earth // First calculates the moon's parrallax, that is, the apparent size of the // (equatorial) radius of the earth, as seen from the moon mpar = asin ( 1 / r); gclat = FG_Latitude - 0.003358 * sin (2 * DEG_TO_RAD * FG_Latitude); rho = 0.99883 + 0.00167 * cos(2 * DEG_TO_RAD * FG_Latitude); if (geoRa < 0) geoRa += (2*FG_PI); HA = t->lst - (3.8197186 * geoRa); g = atan (tan(gclat) / cos ((HA / 3.8197186))); rightAscension = geoRa - mpar * rho * cos(gclat) * sin(HA) / cos (geoDec); declination = geoDec - mpar * rho * sin (gclat) * sin (g - geoDec) / sin(g); } /************************************************************************ * void Moon::newImage(float ra, float dec) * * This function regenerates a new visual image of the moon, which is added to * solarSystem display list. * * Arguments: Right Ascension and declination * * return value: none **************************************************************************/ void Moon::newImage(float ra, float dec) { glEnable(GL_TEXTURE_2D); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); glBindTexture(GL_TEXTURE_2D, moon_texid); //xglRotatef(-90, 0.0, 0.0, 1.0); xglRotatef(((RAD_TO_DEG * ra)- 90.0), 0.0, 0.0, 1.0); xglRotatef((RAD_TO_DEG * dec), 1.0, 0.0, 0.0); fgPrintf( FG_GENERAL, FG_INFO, "Ra = (%f), Dec= (%f)", (RAD_TO_DEG *ra), (RAD_TO_DEG *dec) ); xglTranslatef(0.0, 58600.0, 0.0); Object = gluNewQuadric(); gluQuadricTexture( Object, GL_TRUE ); gluSphere( Object, 1367, 12, 12 ); glDisable(GL_TEXTURE_2D); }