flightgear/Scenery/stars.c

/**************************************************************************
 * 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"


#define EpochStart           (631065600)
#define DaysSinceEpoch(secs) (((secs)-EpochStart)*(1.0/(24*3600)))


static GLint stars;


/* 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;
    double ra_save2, decl_save2;
    int count;

    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");

    printf("Loading Stars: %s\n", path);

    if ( (fd = fopen(path, "r")) == NULL ) {
	printf("Cannot open star file: '%s'\n", path);
	return;
    }

    stars = glGenLists(1);
    glNewList( stars, GL_COMPILE );
    glBegin( GL_POINTS );

    /* read in each line of the file */
    count = 0;
    while ( (fgets(line, 256, fd) != NULL) && (count < FG_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, "Merak") == 0 ) {
		printf("\n*** Marking %s\n\n", name);
		ra_save = right_ascension;
		decl_save = declination;
	    }

	    if ( strcmp(name, "Rastaban") == 0 ) {
		printf("\n*** Marking %s\n\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 * 0.8 + 0.2;

	    printf("Found star: %d %s, %.3f %.3f %.3f\n", count,
	       name, right_ascension, declination, magnitude);

	    glColor3f( magnitude, magnitude, magnitude );
	    glVertex3f( 190000.0 * sin(right_ascension) * cos(declination),
			-190000.0 * cos(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 * sin(ra_save-0.2) * cos(decl_save-0.2),
		    -190000.0 * cos(ra_save-0.2) * cos(decl_save-0.2),
		    190000.0 * sin(decl_save-0.2) );
	glVertex3f( 190000.0 * sin(ra_save+0.2) * cos(decl_save-0.2),
		    -190000.0 * cos(ra_save+0.2) * cos(decl_save-0.2),
		    190000.0 * sin(decl_save-0.2) );
 	glVertex3f( 190000.0 * sin(ra_save+0.2) * cos(decl_save+0.2),
		    -190000.0 * cos(ra_save+0.2) * cos(decl_save+0.2),
		    190000.0 * sin(decl_save+0.2) );
 	glVertex3f( 190000.0 * sin(ra_save-0.2) * cos(decl_save+0.2),
		    -190000.0 * cos(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 * sin(ra_save1-0.2) * cos(decl_save1-0.2),
		    -190000.0 * cos(ra_save1-0.2) * cos(decl_save1-0.2),
		    190000.0 * sin(decl_save1-0.2) );
	glVertex3f( 190000.0 * sin(ra_save1+0.2) * cos(decl_save1-0.2),
		    -190000.0 * cos(ra_save1+0.2) * cos(decl_save1-0.2),
		    190000.0 * sin(decl_save1-0.2) );
 	glVertex3f( 190000.0 * sin(ra_save1+0.2) * cos(decl_save1+0.2),
		    -190000.0 * cos(ra_save1+0.2) * cos(decl_save1+0.2),
		    190000.0 * sin(decl_save1+0.2) );
 	glVertex3f( 190000.0 * sin(ra_save1-0.2) * cos(decl_save1+0.2),
		    -190000.0 * cos(ra_save1-0.2) * cos(decl_save1+0.2),
		    190000.0 * sin(decl_save1+0.2) );
    glEnd();
       
    glEndList();
}


/* Draw the Stars */
void fgStarsRender() {
    struct FLIGHT *f;
    struct VIEW *v;
    double angle;
    static double warp = 0;

    f = &current_aircraft.flight;
    v = &current_view;

    printf("RENDERING STARS\n");

    glDisable( GL_FOG );
    glDisable( GL_LIGHTING );
    glPushMatrix();

    glTranslatef( v->view_pos.x, v->view_pos.y, v->view_pos.z );

    angle = FG_2PI * fmod(DaysSinceEpoch(time(NULL)), 1.0);
    warp += 0.5 * DEG_TO_RAD;
    warp = 240.0 * DEG_TO_RAD;
    glRotatef( -(angle+warp) * RAD_TO_DEG, 0.0, 0.0, 1.0 );
    printf("Rotating stars by %.2f + %.2f\n", -angle * RAD_TO_DEG,
	warp * RAD_TO_DEG);

    glCallList(stars);

    glPopMatrix();
    glEnable( GL_LIGHTING );
    glEnable( GL_FOG );
}


/* $Log$
/* 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.
 *
 */