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flightgear/Scenery/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 "stars.h"
#include "../constants.h"
#include "../general.h"
#include "../GLUT/views.h"
#include "../Aircraft/aircraft.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 GENERAL *g;
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, max_stars;
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] = glGenLists(1);
glNewList( stars[i], GL_COMPILE );
glBegin( 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); */
glColor3f( magnitude, magnitude, magnitude );
glVertex3f( 190000.0 * cos(right_ascension) * cos(declination),
190000.0 * sin(right_ascension) * cos(declination),
190000.0 * sin(declination) );
count++;
} /* if valid line */
} /* while */
fclose(fd);
glEnd();
glBegin(GL_LINE_LOOP);
glColor3f(1.0, 0.0, 0.0);
glVertex3f( 190000.0 * cos(ra_save-0.2) * cos(decl_save-0.2),
190000.0 * sin(ra_save-0.2) * cos(decl_save-0.2),
190000.0 * sin(decl_save-0.2) );
glVertex3f( 190000.0 * cos(ra_save+0.2) * cos(decl_save-0.2),
190000.0 * sin(ra_save+0.2) * cos(decl_save-0.2),
190000.0 * sin(decl_save-0.2) );
glVertex3f( 190000.0 * cos(ra_save+0.2) * cos(decl_save+0.2),
190000.0 * sin(ra_save+0.2) * cos(decl_save+0.2),
190000.0 * sin(decl_save+0.2) );
glVertex3f( 190000.0 * cos(ra_save-0.2) * cos(decl_save+0.2),
190000.0 * sin(ra_save-0.2) * cos(decl_save+0.2),
190000.0 * sin(decl_save+0.2) );
glEnd();
glBegin(GL_LINE_LOOP);
glColor3f(0.0, 1.0, 0.0);
glVertex3f( 190000.0 * cos(ra_save1-0.2) * cos(decl_save1-0.2),
190000.0 * sin(ra_save1-0.2) * cos(decl_save1-0.2),
190000.0 * sin(decl_save1-0.2) );
glVertex3f( 190000.0 * cos(ra_save1+0.2) * cos(decl_save1-0.2),
190000.0 * sin(ra_save1+0.2) * cos(decl_save1-0.2),
190000.0 * sin(decl_save1-0.2) );
glVertex3f( 190000.0 * cos(ra_save1+0.2) * cos(decl_save1+0.2),
190000.0 * sin(ra_save1+0.2) * cos(decl_save1+0.2),
190000.0 * sin(decl_save1+0.2) );
glVertex3f( 190000.0 * cos(ra_save1-0.2) * cos(decl_save1+0.2),
190000.0 * sin(ra_save1-0.2) * cos(decl_save1+0.2),
190000.0 * sin(decl_save1+0.2) );
glEnd();
glEndList();
max_stars /= 2;
}
}
/* Draw the Stars */
void fgStarsRender() {
struct FLIGHT *f;
struct VIEW *v;
struct fgTIME *t;
double angle;
static double warp = 0;
int i;
f = &current_aircraft.flight;
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; /* force stars (for testing) */
if ( t->sun_angle > (FG_PI_2 + 5 * DEG_TO_RAD ) ) {
/* determine which star structure to draw */
if ( t->sun_angle > (FG_PI_2 + 7.25 * DEG_TO_RAD ) ) {
i = 0;
} else if ( t->sun_angle > (FG_PI_2 + 6.50 * DEG_TO_RAD ) ) {
i = 1;
} else if ( t->sun_angle > (FG_PI_2 + 5.75 * DEG_TO_RAD ) ) {
i = 2;
} else {
i = 3;
}
printf("RENDERING STARS = %d (night)\n", i);
glDisable( GL_FOG );
glDisable( GL_LIGHTING );
glPushMatrix();
glTranslatef( v->view_pos.x, v->view_pos.y, v->view_pos.z );
angle = t->gst * 15.0; /* 15 degrees per hour rotation */
/* warp += 1.0; */
/* warp = 15.0; */
warp = 0.0;
glRotatef( (angle+warp), 0.0, 0.0, -1.0 );
printf("Rotating stars by %.2f degrees + %.2f degrees\n",angle,warp);
glCallList(stars[i]);
glPopMatrix();
glEnable( GL_LIGHTING );
glEnable( GL_FOG );
} else {
printf("not RENDERING STARS (day)\n");
}
}
/* $Log$
/* 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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