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flightgear/Astro/sun.cxx

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/**************************************************************************
* 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)
**************************************************************************/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#ifdef HAVE_WINDOWS_H
# include <windows.h>
#endif
#include <GL/glut.h>
#include <XGL/xgl.h>
#include <Debug/fg_debug.h>
#include <Include/fg_constants.h>
#include <Main/views.hxx>
#include <Time/fg_time.hxx>
#include <Time/sunpos.hxx>
#include "orbits.hxx"
#include "sun.hxx"
GLint sun_obj = 0;
static struct CelestialCoord sunPos;
fgSUNPOS solarPosition;
void fgCalcSunPos(struct OrbElements params)
{
double EccAnom, xv, yv, v, r;
/* 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) */
solarPosition.lonSun = v + params.w;
/* convert true longitude and distance to ecliptic rectangular
geocentric coordinates (xs, ys) */
solarPosition.xs = r * cos (solarPosition.lonSun);
solarPosition.ys = r * sin (solarPosition.lonSun);
solarPosition.dist = r;
/* return solarPosition; */
}
struct CelestialCoord fgCalculateSun (struct OrbElements params,
struct fgTIME t)
{
struct CelestialCoord result;
double xe, ye, ze, ecl, actTime;
/* calculate the angle between ecliptic and equatorial coordinate
* system */
actTime = fgCalcActTime (t);
ecl = DEG_TO_RAD * (23.4393 - 3.563E-7 * actTime); // Angle now in Rads
/* calculate the sun's ecliptic position */
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( void ) {
fgLIGHT *l;
struct fgTIME *t;
struct fgVIEW *v;
float xSun, ySun, zSun;
/* GLfloat color[4] = { 1.00, 1.00, 1.00, 1.00 }; */
double x_2, x_4, x_8, x_10;
GLfloat ambient;
GLfloat amb[4];
l = &cur_light_params;
t = &cur_time_params;
v = &current_view;
fgPrintf( FG_ASTRO, FG_INFO, " Initializing the Sun\n");
// Calculate basic sun position
fgSolarSystemUpdate(&(pltOrbElements[0]), cur_time_params);
sunPos = fgCalculateSun(pltOrbElements[0], cur_time_params);
// Calculate additional sun position parameters based on the above
// position that are needed by other parts of FG
fgUpdateSunPos();
fgPrintf( FG_ASTRO, FG_INFO,
"Sun found at %f (ra), %f (dec)\n",
sunPos.RightAscension, sunPos.Declination);
xSun = 60000.0 * cos(sunPos.RightAscension) * cos(sunPos.Declination);
ySun = 60000.0 * sin(sunPos.RightAscension) * cos(sunPos.Declination);
zSun = 60000.0 * sin(sunPos.Declination);
if (sun_obj) {
xglDeleteLists(sun_obj, 1);
}
/* printf("First time through, creating sun display list\n"); */
sun_obj = xglGenLists(1);
xglNewList(sun_obj, GL_COMPILE );
t = &cur_time_params;
v = &current_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] = 0.00 + ((ambient * 6.0) - 1.0); /* minimum val = 0.8 */
amb[1] = 0.00 + ((ambient * 11.0) - 3.0); /* minimum val = 0.3 */
amb[2] = 0.00 + ((ambient * 12.0) - 3.6); /* minimum val = 0.0 */
amb[3] = 1.00;
if (amb[0] > 1.0) amb[0] = 1.0;
if (amb[1] > 1.0) amb[1] = 1.0;
if (amb[2] > 1.0) amb[2] = 1.0;
fgPrintf( FG_ASTRO, FG_DEBUG,
"Color of the sun: %f, %f, %f\n"
"Ambient value : %f\n"
"Sun Angle : %f\n" ,
amb[0], amb[1], amb[2], ambient, l->sun_angle);
xglPushMatrix();
xglTranslatef(xSun, ySun, zSun);
xglScalef(1400, 1400, 1400);
xglColor3f(amb[0], amb[1], amb[2]);
glutSolidSphere(1.0, 10, 10);
xglPopMatrix();
xglEndList();
}
/* Draw the Sun */
void fgSunRender( void ) {
xglCallList(sun_obj);
}
/* $Log$
/* Revision 1.4 1998/04/26 05:10:02 curt
/* "struct fgLIGHT" -> "fgLIGHT" because fgLIGHT is typedef'd.
/*
* Revision 1.3 1998/04/25 22:06:26 curt
* Edited cvs log messages in source files ... bad bad bad!
*
* Revision 1.2 1998/04/24 00:45:04 curt
* Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
* Fixed a bug when generating sky colors.
*
* Revision 1.1 1998/04/22 13:21:36 curt
* C++ - ifing the code a bit.
*
* Revision 1.10 1998/04/18 04:13:58 curt
* Moved fg_debug.c to it's own library.
*
* Revision 1.9 1998/04/03 21:52:51 curt
* Converting to Gnu autoconf system.
*
* Revision 1.8 1998/03/09 22:47:25 curt
* Incorporated Durk's updates.
*
* Revision 1.7 1998/02/23 19:07:56 curt
* Incorporated Durk's Astro/ tweaks. Includes unifying the sun position
* calculation code between sun display, and other FG sections that use this
* for things like lighting.
*
* Revision 1.6 1998/02/12 21:59:39 curt
* Incorporated code changes contributed by Charlie Hotchkiss
* <chotchkiss@namg.us.anritsu.com>
*
* Revision 1.5 1998/02/02 20:53:24 curt
* To version 0.29
*
* Revision 1.4 1998/01/27 00:47:50 curt
* Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
* system and commandline/config file processing code.
*
* Revision 1.3 1998/01/19 19:27:00 curt
* Merged in make system changes from Bob Kuehne <rpk@sgi.com>
* This should simplify things tremendously.
*
* Revision 1.2 1998/01/19 18:40:18 curt
* Tons of little changes to clean up the code and to remove fatal errors
* when building with the c++ compiler.
*
* Revision 1.1 1998/01/07 03:16:20 curt
* Moved from .../Src/Scenery/ to .../Src/Astro/
*
* Revision 1.12 1998/01/05 18:44:36 curt
* Add an option to advance/decrease time from keyboard.
*
* 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.
*
*/
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