286 lines
8.9 KiB
C++
286 lines
8.9 KiB
C++
/**************************************************************************
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* moon.c
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* Written by Durk Talsma. Started October 1997, for the flight gear project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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* (Log is kept at end of this file)
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**************************************************************************/
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#ifdef HAVE_WINDOWS_H
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# include <windows.h>
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#endif
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#include <math.h>
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#include <GL/glut.h>
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#include <XGL/xgl.h>
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#include <Aircraft/aircraft.h>
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#include <Debug/fg_debug.h>
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#include <Include/fg_constants.h>
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#include <Include/general.h>
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#include <Main/views.hxx>
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#include <Time/fg_time.hxx>
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#include "orbits.hxx"
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#include "moon.hxx"
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struct CelestialCoord moonPos;
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static float xMoon, yMoon, zMoon;
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static GLint moon = 0;
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/* --------------------------------------------------------------
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This section contains the code that calculates the actual
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position of the moon in the night sky.
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----------------------------------------------------------------*/
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struct CelestialCoord fgCalculateMoon(struct OrbElements params,
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struct OrbElements sunParams,
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fgTIME t)
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{
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struct CelestialCoord
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geocCoord, topocCoord;
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double
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eccAnom, ecl, lonecl, latecl, actTime,
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xv, yv, v, r, xh, yh, zh, xg, yg, zg, xe, ye, ze,
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Ls, Lm, D, F, mpar, gclat, rho, HA, g;
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fgAIRCRAFT *a;
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fgFLIGHT *f;
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a = ¤t_aircraft;
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f = a->flight;
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/* calculate the angle between ecliptic and equatorial coordinate
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* system, in Radians */
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actTime = fgCalcActTime(t);
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ecl = ((DEG_TO_RAD * 23.4393) - (DEG_TO_RAD * 3.563E-7) * actTime);
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/*ecl = 0.409093 - 6.2186E-9 * actTime; */
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/* calculate the eccentric anomaly */
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eccAnom = fgCalcEccAnom(params.M, params.e);
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/* calculate the moon's distance (r) and true anomaly (v) */
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xv = params.a * ( cos(eccAnom) - params.e);
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yv = params.a * ( sqrt(1.0 - params.e*params.e) * sin(eccAnom));
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v =atan2(yv, xv);
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r = sqrt(xv*xv + yv*yv);
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/* estimate the geocentric rectangular coordinates here */
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xh = r * (cos (params.N) * cos (v + params.w) -
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sin (params.N) * sin (v + params.w) * cos (params.i));
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yh = r * (sin (params.N) * cos (v + params.w) +
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cos (params.N) * sin (v + params.w) * cos (params.i));
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zh = r * (sin(v + params.w) * sin(params.i));
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/* calculate the ecliptic latitude and longitude here */
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lonecl = atan2( yh, xh);
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latecl = atan2( zh, sqrt( xh*xh + yh*yh));
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/* calculate a number of perturbations, i.e. disturbances caused by
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* the gravitational influence of the sun and the other mayor
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* planets. The largest of these even have their own names */
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Ls = sunParams.M + sunParams.w;
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Lm = params.M + params.w + params.N;
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D = Lm - Ls;
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F = Lm - params.N;
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lonecl += DEG_TO_RAD * (
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- 1.274 * sin (params.M - 2*D) /* the Evection */
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+ 0.658 * sin (2 * D) /* the Variation */
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- 0.186 * sin (sunParams.M) /* the yearly variation */
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- 0.059 * sin (2*params.M - 2*D)
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- 0.057 * sin (params.M - 2*D + sunParams.M)
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+ 0.053 * sin (params.M + 2*D)
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+ 0.046 * sin (2*D - sunParams.M)
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+ 0.041 * sin (params.M - sunParams.M)
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- 0.035 * sin (D) /* the Parallactic Equation */
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- 0.031 * sin (params.M + sunParams.M)
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- 0.015 * sin (2*F - 2*D)
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+ 0.011 * sin (params.M - 4*D)
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);
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latecl += DEG_TO_RAD * (
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- 0.173 * sin (F - 2*D)
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- 0.055 * sin (params.M - F - 2*D)
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- 0.046 * sin (params.M + F - 2*D)
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+ 0.033 * sin (F + 2*D)
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+ 0.017 * sin (2 * params.M + F)
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);
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r += (
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- 0.58 * cos(params.M - 2*D)
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- 0.46 * cos(2*D)
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);
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xg = r * cos(lonecl) * cos(latecl);
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yg = r * sin(lonecl) * cos(latecl);
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zg = r * sin(latecl);
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xe = xg;
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ye = yg * cos(ecl) - zg * sin(ecl);
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ze = yg * sin(ecl) + zg * cos(ecl);
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geocCoord.RightAscension = atan2(ye, xe);
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geocCoord.Declination = atan2(ze, sqrt(xe*xe + ye*ye));
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/* New since 25 december 1997 */
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/* Calculate the moon's topocentric position instead of it's geocentric! */
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/* calculate the moon's parrallax, i.e. the apparent size of the
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* (equatorial) radius of the Earth, as seen from the moon */
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mpar = asin( 1 / r);
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gclat = FG_Latitude - 0.083358 * sin (2 * DEG_TO_RAD * FG_Latitude);
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rho = 0.99883 + 0.00167 * cos(2 * DEG_TO_RAD * FG_Latitude);
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if (geocCoord.RightAscension < 0)
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geocCoord.RightAscension += (2*FG_PI);
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HA = t.lst - (3.8197186 * geocCoord.RightAscension);
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g = atan (tan(gclat) / cos( (HA / 3.8197186)));
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topocCoord.RightAscension = geocCoord.RightAscension -
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mpar * rho * cos (gclat) * sin (HA) / cos (geocCoord.Declination);
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topocCoord.Declination = geocCoord.Declination -
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mpar * rho * sin (gclat) * sin (g - geocCoord.Declination) / sin (g);
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return topocCoord;
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}
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void fgMoonInit( void ) {
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fgPrintf( FG_ASTRO, FG_INFO, "Initializing the Moon\n");
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fgSolarSystemUpdate(&(pltOrbElements[1]), cur_time_params);
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moonPos = fgCalculateMoon(pltOrbElements[1], pltOrbElements[0],
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cur_time_params);
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fgPrintf( FG_ASTRO, FG_DEBUG,
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"Moon found at %f (ra), %f (dec)\n", moonPos.RightAscension,
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moonPos.Declination);
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xMoon = 60000.0 * cos(moonPos.RightAscension) * cos(moonPos.Declination);
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yMoon = 60000.0 * sin(moonPos.RightAscension) * cos(moonPos.Declination);
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zMoon = 60000.0 * sin(moonPos.Declination);
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if (moon) {
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xglDeleteLists (moon, 1);
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}
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moon = xglGenLists (1);
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xglNewList (moon, GL_COMPILE);
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xglPushMatrix ();
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xglTranslatef (xMoon, yMoon, zMoon);
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// xglScalef (1400, 1400, 1400);
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// glutSolidSphere (1.0, 10, 10);
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glutSolidSphere (1200.0, 10, 10);
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xglPopMatrix ();
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xglEndList ();
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}
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/* Draw the moon */
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void fgMoonRender( void ) {
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GLfloat moonColor[4] = {0.85, 0.75, 0.35, 1.0};
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GLfloat black[4] = { 0.0, 0.0, 0.0, 1.0 };
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xglMaterialfv (GL_FRONT, GL_AMBIENT, black);
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xglMaterialfv (GL_FRONT, GL_DIFFUSE, moonColor);
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xglCallList(moon);
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}
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/* $Log$
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/* Revision 1.6 1998/09/03 21:25:39 curt
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/* log file tweak.
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/*
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* Revision 1.5 1998/07/30 23:43:30 curt
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* Eliminated glScale call so that glutSolidSphere normals are preserved
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* correctly. Also made the sun & moon a bit smaller.
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*
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* Revision 1.4 1998/04/28 01:18:59 curt
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* Type-ified fgTIME and fgVIEW
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*
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* Revision 1.3 1998/04/25 22:06:24 curt
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* Edited cvs log messages in source files ... bad bad bad!
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*
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* Revision 1.2 1998/04/24 00:45:00 curt
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* Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
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* Fixed a bug when generating sky colors.
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*
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* Revision 1.1 1998/04/22 13:21:28 curt
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* C++ - ifing the code a bit.
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*
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* Revision 1.9 1998/04/18 04:13:56 curt
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* Moved fg_debug.c to it's own library.
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*
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* Revision 1.8 1998/04/03 21:52:49 curt
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* Converting to Gnu autoconf system.
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*
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* Revision 1.7 1998/02/23 19:07:54 curt
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* Incorporated Durk's Astro/ tweaks. Includes unifying the sun position
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* calculation code between sun display, and other FG sections that use this
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* for things like lighting.
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*
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* Revision 1.6 1998/02/07 15:29:32 curt
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* Incorporated HUD changes and struct/typedef changes from Charlie Hotchkiss
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* <chotchkiss@namg.us.anritsu.com>
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*
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* Revision 1.5 1998/02/02 20:53:21 curt
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* To version 0.29
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*
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* Revision 1.4 1998/01/27 00:47:46 curt
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* Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
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* system and commandline/config file processing code.
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*
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* Revision 1.3 1998/01/19 19:26:57 curt
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* Merged in make system changes from Bob Kuehne <rpk@sgi.com>
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* This should simplify things tremendously.
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*
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* Revision 1.2 1998/01/19 18:40:16 curt
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* Tons of little changes to clean up the code and to remove fatal errors
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* when building with the c++ compiler.
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*
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* Revision 1.1 1998/01/07 03:16:16 curt
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* Moved from .../Src/Scenery/ to .../Src/Astro/
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*
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* Revision 1.16 1998/01/06 01:20:24 curt
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* Tweaks to help building with MSVC++
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*
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* Revision 1.15 1998/01/05 18:44:35 curt
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* Add an option to advance/decrease time from keyboard.
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*
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* Revision 1.14 1997/12/30 20:47:50 curt
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* Integrated new event manager with subsystem initializations.
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*
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* Revision 1.13 1997/12/30 16:41:00 curt
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* Added log at end of file.
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*
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*/
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