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simgear/Astro/stars.c

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/**************************************************************************
* stars.c -- data structures and routines for managing and rendering stars.
*
* Written by Curtis Olson, started August 1997.
*
* Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
*
* 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 WIN32
# include <windows.h>
#endif
#include <math.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <GL/glut.h>
#include "../XGL/xgl.h"
#include "orbits.h"
#include "planets.h"
#include "stars.h"
#include "../Include/constants.h"
#include "../Include/general.h"
#include "../Aircraft/aircraft.h"
#include "../Main/views.h"
#include "../Time/fg_time.h"
#define EpochStart (631065600)
#define DaysSinceEpoch(secs) (((secs)-EpochStart)*(1.0/(24*3600)))
/* Define four structures, each with varying amounts of stars */
/* static */ GLint stars[FG_STAR_LEVELS];
/* Initialize the Star Management Subsystem */
void fgStarsInit() {
FILE *fd;
struct fgGENERAL *g;
struct CelestialCoord pltPos;
char path[1024];
char line[256], name[256];
char *front, *end;
double right_ascension, declination, magnitude;
double ra_save, decl_save;
double ra_save1, decl_save1;
int count, i, j, max_stars;
printf("Initializing stars\n");
g = &general;
/* build the full path name to the stars data base file */
path[0] = '\0';
strcat(path, g->root_dir);
strcat(path, "/Scenery/");
strcat(path, "Stars.dat");
max_stars = FG_MAX_STARS;
for ( i = 0; i < FG_STAR_LEVELS; i++ ) {
printf(" Loading %d Stars: %s\n", max_stars, path);
if ( (fd = fopen(path, "r")) == NULL ) {
printf("Cannot open star file: '%s'\n", path);
return;
}
stars[i] = xglGenLists(1);
xglNewList( stars[i], GL_COMPILE );
xglBegin( GL_POINTS );
/* read in each line of the file */
count = 0;
while ( (fgets(line, 256, fd) != NULL) && (count < max_stars) ) {
front = line;
/* printf(" Read line = %s", front); */
/* advance to first non-whitespace character */
while ( (front[0] == ' ') || (front[0] == '\t') ) {
front++;
}
/* printf(" Line length (after trimming) = %d\n", strlen(front));*/
if ( front[0] == '#' ) {
/* comment */
} else if ( strlen(front) <= 1 ) {
/* blank line */
} else {
/* star data line */
/* get name */
end = front;
while ( end[0] != ',' ) {
end++;
}
end[0] = '\0';
strcpy(name, front);
front = end;
front++;
sscanf(front, "%lf,%lf,%lf\n",
&right_ascension, &declination, &magnitude);
/*
if ( strcmp(name, "Betelgeuse") == 0 ) {
printf(" *** Marking %s\n", name);
ra_save = right_ascension;
decl_save = declination;
}
*/
/*
if ( strcmp(name, "Alnilam") == 0 ) {
printf(" *** Marking %s\n", name);
ra_save1 = right_ascension;
decl_save1 = declination;
}
*/
/* scale magnitudes to (0.0 - 1.0) */
magnitude = (0.0 - magnitude) / 5.0 + 1.0;
/* scale magnitudes again so they look ok */
if ( magnitude > 1.0 ) { magnitude = 1.0; }
if ( magnitude < 0.0 ) { magnitude = 0.0; }
magnitude =
magnitude * 0.7 + (((FG_STAR_LEVELS - 1) - i) * 0.1);
/* printf(" Found star: %d %s, %.3f %.3f %.3f\n", count,
name, right_ascension, declination, magnitude); */
xglColor3f( magnitude, magnitude, magnitude );
/*xglColor3f(0,0,0);*/
xglVertex3f( 50000.0 * cos(right_ascension) * cos(declination),
50000.0 * sin(right_ascension) * cos(declination),
50000.0 * sin(declination) );
count++;
} /* if valid line */
} /* while */
fclose(fd);
/* Add the planets to all four display lists */
for ( j = 2; j < 9; j++ ) {
pltPos = fgCalculatePlanet(pltOrbElements[j],
pltOrbElements[0], cur_time_params, j);
/* give the planets a temporary color, for testing purposes */
/* xglColor3f( 1.0, 0.0, 0.0); */
/* scale magnitudes to (0.0 - 1.0) */
magnitude = (0.0 - pltPos.magnitude) / 5.0 + 1.0;
/* scale magnitudes again so they look ok */
if ( magnitude > 1.0 ) { magnitude = 1.0; }
if ( magnitude < 0.0 ) { magnitude = 0.0; }
magnitude =
magnitude * 0.7 + (((FG_STAR_LEVELS - 1) - i) * 0.1);
xglColor3f(magnitude, magnitude, magnitude);
xglVertex3f( 50000.0 * cos(pltPos.RightAscension) *
cos(pltPos.Declination),
50000.0 * sin(pltPos.RightAscension) *
cos(pltPos.Declination),
50000.0 * sin(pltPos.Declination) );
}
xglEnd();
/*
xglBegin(GL_LINE_LOOP);
xglColor3f(1.0, 0.0, 0.0);
xglVertex3f( 50000.0 * cos(ra_save-0.2) * cos(decl_save-0.2),
50000.0 * sin(ra_save-0.2) * cos(decl_save-0.2),
50000.0 * sin(decl_save-0.2) );
xglVertex3f( 50000.0 * cos(ra_save+0.2) * cos(decl_save-0.2),
50000.0 * sin(ra_save+0.2) * cos(decl_save-0.2),
50000.0 * sin(decl_save-0.2) );
xglVertex3f( 50000.0 * cos(ra_save+0.2) * cos(decl_save+0.2),
50000.0 * sin(ra_save+0.2) * cos(decl_save+0.2),
50000.0 * sin(decl_save+0.2) );
xglVertex3f( 50000.0 * cos(ra_save-0.2) * cos(decl_save+0.2),
50000.0 * sin(ra_save-0.2) * cos(decl_save+0.2),
50000.0 * sin(decl_save+0.2) );
xglEnd();
*/
/*
xglBegin(GL_LINE_LOOP);
xglColor3f(0.0, 1.0, 0.0);
xglVertex3f( 50000.0 * cos(ra_save1-0.2) * cos(decl_save1-0.2),
50000.0 * sin(ra_save1-0.2) * cos(decl_save1-0.2),
50000.0 * sin(decl_save1-0.2) );
xglVertex3f( 50000.0 * cos(ra_save1+0.2) * cos(decl_save1-0.2),
50000.0 * sin(ra_save1+0.2) * cos(decl_save1-0.2),
50000.0 * sin(decl_save1-0.2) );
xglVertex3f( 50000.0 * cos(ra_save1+0.2) * cos(decl_save1+0.2),
50000.0 * sin(ra_save1+0.2) * cos(decl_save1+0.2),
50000.0 * sin(decl_save1+0.2) );
xglVertex3f( 50000.0 * cos(ra_save1-0.2) * cos(decl_save1+0.2),
50000.0 * sin(ra_save1-0.2) * cos(decl_save1+0.2),
50000.0 * sin(decl_save1+0.2) );
xglEnd();
*/
xglEndList();
max_stars /= 2;
}
}
/* Draw the Stars */
void fgStarsRender() {
struct fgFLIGHT *f;
struct fgVIEW *v;
struct fgLIGHT *l;
struct fgTIME *t;
int i;
f = &current_aircraft.flight;
l = &cur_light_params;
t = &cur_time_params;
v = &current_view;
/* FG_PI_2 + 0.1 is about 6 degrees after sundown and before sunrise */
/* t->sun_angle = 3.0; */ /* to force stars to be drawn (for testing) */
/* render the stars */
if ( l->sun_angle > (FG_PI_2 + 5 * DEG_TO_RAD ) ) {
/* determine which star structure to draw */
if ( l->sun_angle > (FG_PI_2 + 7.25 * DEG_TO_RAD ) ) {
i = 0;
} else if ( l->sun_angle > (FG_PI_2 + 6.50 * DEG_TO_RAD ) ) {
i = 1;
} else if ( l->sun_angle > (FG_PI_2 + 5.75 * DEG_TO_RAD ) ) {
i = 2;
} else {
i = 3;
}
/* printf("RENDERING STARS = %d (night)\n", i); */
xglCallList(stars[i]);
} else {
/* printf("not RENDERING STARS (day)\n"); */
}
}
/* $Log$
/* Revision 1.1 1998/01/07 03:16:20 curt
/* Moved from .../Src/Scenery/ to .../Src/Astro/
/*
* Revision 1.24 1997/12/30 22:22:39 curt
* Further integration of event manager.
*
* Revision 1.23 1997/12/30 20:47:53 curt
* Integrated new event manager with subsystem initializations.
*
* Revision 1.22 1997/12/30 16:36:53 curt
* Merged in Durk's changes ...
*
* Revision 1.21 1997/12/19 23:35:00 curt
* Lot's of tweaking with sky rendering and lighting.
*
* Revision 1.20 1997/12/15 23:55:03 curt
* Add xgl wrappers for debugging.
* Generate terrain normals on the fly.
*
* Revision 1.19 1997/12/12 19:53:00 curt
* Working on lightling and material properties.
*
* Revision 1.18 1997/12/10 22:37:52 curt
* Prepended "fg" on the name of all global structures that didn't have it yet.
* i.e. "struct WEATHER {}" became "struct fgWEATHER {}"
*
* Revision 1.17 1997/12/09 04:25:33 curt
* Working on adding a global lighting params structure.
*
* Revision 1.16 1997/11/25 19:25:38 curt
* Changes to integrate Durk's moon/sun code updates + clean up.
*
* Revision 1.15 1997/10/30 12:38:45 curt
* Working on new scenery subsystem.
*
* Revision 1.14 1997/10/28 21:00:22 curt
* Changing to new terrain format.
*
* Revision 1.13 1997/10/25 03:18:28 curt
* Incorporated sun, moon, and planet position and rendering code contributed
* by Durk Talsma.
*
* Revision 1.12 1997/09/23 00:29:43 curt
* Tweaks to get things to compile with gcc-win32.
*
* Revision 1.11 1997/09/22 14:44:21 curt
* Continuing to try to align stars correctly.
*
* Revision 1.10 1997/09/20 03:34:32 curt
* Still trying to get those durned stars aligned properly.
*
* Revision 1.9 1997/09/18 16:20:09 curt
* At dusk/dawn add/remove stars in stages.
*
* Revision 1.8 1997/09/16 22:14:52 curt
* Tweaked time of day lighting equations. Don't draw stars during the day.
*
* Revision 1.7 1997/09/16 15:50:31 curt
* Working on star alignment and time issues.
*
* Revision 1.6 1997/09/05 14:17:31 curt
* More tweaking with stars.
*
* Revision 1.5 1997/09/05 01:35:59 curt
* Working on getting stars right.
*
* Revision 1.4 1997/09/04 02:17:38 curt
* Shufflin' stuff.
*
* Revision 1.3 1997/08/29 17:55:28 curt
* Worked on properly aligning the stars.
*
* Revision 1.2 1997/08/27 21:32:30 curt
* Restructured view calculation code. Added stars.
*
* Revision 1.1 1997/08/27 03:34:48 curt
* Initial revision.
*
*/
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