/************************************************************************** * sun.c * * Written 1997 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 "../XGL/xgl.h" #include "../Time/fg_time.h" #include "../Main/views.h" #include "orbits.h" #include "sun.h" GLint sun_obj; static struct CelestialCoord sunPos; float xSun, ySun, zSun; struct SunPos fgCalcSunPos(struct OrbElements params) { double EccAnom, lonSun, xv, yv, v, r; struct SunPos solarPosition; /* calculate the eccentric anomaly */ EccAnom = fgCalcEccAnom(params.M, params.e); /* calculate the Suns distance (r) and its true anomaly (v) */ xv = cos(EccAnom) - params.e; yv = sqrt(1.0 - params.e*params.e) * sin(EccAnom); v = atan2(yv, xv); r = sqrt(xv*xv + yv*yv); /* calculate the the Sun's true longitude (lonsun) */ lonSun = v + params.w; /* convert true longitude and distance to ecliptic rectangular geocentric coordinates (xs, ys) */ solarPosition.xs = r * cos(lonSun); solarPosition.ys = r * sin(lonSun); solarPosition.dist = r; return solarPosition; } struct CelestialCoord fgCalculateSun(struct OrbElements params, struct fgTIME t) { struct CelestialCoord result; struct SunPos SolarPosition; double xe, ye, ze, ecl, actTime; /* calculate the angle between ecliptic and equatorial coordinate system */ actTime = fgCalcActTime(t); ecl = fgDegToRad(23.4393 - 3.563E-7 * actTime); // Angle now in Rads /* calculate the sun's ecliptic position */ SolarPosition = fgCalcSunPos(params); /* convert ecliptic coordinates to equatorial rectangular geocentric coordinates */ xe = SolarPosition.xs; ye = SolarPosition.ys * cos(ecl); ze = SolarPosition.ys * sin(ecl); /* and finally... Calulate Right Ascention and Declination */ result.RightAscension = atan2( ye, xe); result.Declination = atan2(ze, sqrt(xe*xe + ye*ye)); return result; } /* Initialize the Sun */ void fgSunInit() { static int dl_exists = 0; printf(" Initializing the Sun\n"); fgSolarSystemUpdate(&(pltOrbElements[0]), cur_time_params); sunPos = fgCalculateSun(pltOrbElements[0], cur_time_params); #ifdef DEBUG printf("Sun found at %f (ra), %f (dec)\n", sunPos.RightAscension, sunPos.Declination); #endif if ( !dl_exists ) { dl_exists = 1; /* printf("First time through, creating sun display list\n"); */ sun_obj = xglGenLists(1); xglNewList(sun_obj, GL_COMPILE ); xSun = 60000.0 * cos(sunPos.RightAscension) * cos(sunPos.Declination); ySun = 60000.0 * sin(sunPos.RightAscension) * cos(sunPos.Declination); zSun = 60000.0 * sin(sunPos.Declination); glutSolidSphere(1.0, 10, 10); xglEndList(); } } /* Draw the Sun */ void fgSunRender() { struct fgVIEW *v; struct fgTIME *t; struct fgLIGHT *l; /* GLfloat color[4] = { 0.85, 0.65, 0.05, 1.0 }; */ GLfloat color[4] = { 1.00, 1.00, 1.00, 1.00 }; double x_2, x_4, x_8, x_10; GLfloat ambient; GLfloat amb[3], diff[3]; t = &cur_time_params; v = ¤t_view; l = &cur_light_params; x_2 = l->sun_angle * l->sun_angle; x_4 = x_2 * x_2; x_8 = x_4 * x_4; x_10 = x_8 * x_2; ambient = (0.4 * pow(1.1, -x_10 / 30.0)); if ( ambient < 0.3 ) ambient = 0.3; if ( ambient > 1.0 ) ambient = 1.0; amb[0] = 0.50 + ((ambient * 6.66) - 1.6); amb[1] = 0.00 + ((ambient * 6.66) - 1.6); amb[2] = 0.00 + ((ambient * 6.66) - 1.6); amb[3] = 0.00; #ifdef DEBUG printf("Color of the sun: %f, %f, %f\n" "Ambient value : %f\n" "Sun Angle : %f\n" , amb[0], amb[1], amb[2], ambient, t->sun_angle); #endif diff[0] = 0.0; diff[1] = 0.0; diff[2] = 0.0; diff[3] = 1.0; /* set lighting parameters */ xglLightfv(GL_LIGHT0, GL_AMBIENT, color ); xglLightfv(GL_LIGHT0, GL_DIFFUSE, color ); xglMaterialfv(GL_FRONT, GL_AMBIENT, amb); xglMaterialfv(GL_FRONT, GL_DIFFUSE, diff); xglMaterialfv(GL_FRONT, GL_SHININESS, diff); xglMaterialfv(GL_FRONT, GL_EMISSION, diff); xglMaterialfv(GL_FRONT, GL_SPECULAR, diff); /* xglDisable( GL_LIGHTING ); */ xglPushMatrix(); xglTranslatef(xSun, ySun, zSun); xglScalef(1400, 1400, 1400); xglColor3f(0.85, 0.65, 0.05); xglCallList(sun_obj); xglPopMatrix(); /* xglEnable( GL_LIGHTING ); */ } /* $Log$ /* Revision 1.11 1997/12/30 23:09:40 curt /* Worked on winding problem without luck, so back to calling glFrontFace() /* 3 times for each scenery area. /* * Revision 1.10 1997/12/30 20:47:54 curt * Integrated new event manager with subsystem initializations. * * Revision 1.9 1997/12/30 16:36:54 curt * Merged in Durk's changes ... * * Revision 1.8 1997/12/19 23:35:00 curt * Lot's of tweaking with sky rendering and lighting. * * Revision 1.7 1997/12/17 23:12:16 curt * Fixed so moon and sun display lists aren't recreate periodically. * * Revision 1.6 1997/12/15 23:55:04 curt * Add xgl wrappers for debugging. * Generate terrain normals on the fly. * * Revision 1.5 1997/12/12 21:41:31 curt * More light/material property tweaking ... still a ways off. * * Revision 1.4 1997/12/10 22:37:53 curt * Prepended "fg" on the name of all global structures that didn't have it yet. * i.e. "struct WEATHER {}" became "struct fgWEATHER {}" * * Revision 1.3 1997/12/09 05:11:56 curt * Working on tweaking lighting. * * Revision 1.2 1997/11/25 19:25:39 curt * Changes to integrate Durk's moon/sun code updates + clean up. * * Revision 1.1 1997/10/25 03:16:11 curt * Initial revision of code contributed by Durk Talsma. * */