// stars.cxx -- data structures and routines for managing and rendering stars.
//
// Written by Curtis Olson, started August 1997.
//
// Copyright (C) 1997  Curtis L. Olson  - curt@me.umn.edu
//
// 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 <math.h>
#include <stdio.h>
#include <string.h>
#include <string>
#include <time.h>

#include <GL/glut.h>
#include <XGL/xgl.h>

#include <Aircraft/aircraft.h>
#include <Debug/fg_debug.h>
#include <Include/fg_constants.h>
#include <Include/fg_types.h>
#include <Misc/fgstream.hxx>
#include <Main/options.hxx>
#include <Main/views.hxx>
#include <Misc/stopwatch.hxx>
#include <Time/fg_time.hxx>

#include "stars.hxx"


#define EpochStart           (631065600)
#define DaysSinceEpoch(secs) (((secs)-EpochStart)*(1.0/(24*3600)))
#define FG_MAX_STARS 3500

// Define four structures, each with varying amounts of stars
static GLint stars[FG_STAR_LEVELS];


// Initialize the Star Management Subsystem
int fgStarsInit( void ) {
    fgPoint3d starlist[FG_MAX_STARS];
    // struct CelestialCoord pltPos;
    double right_ascension, declination, magnitude;
    double min_magnitude[FG_STAR_LEVELS];
    // double ra_save, decl_save;
    // double ra_save1, decl_save1;
    int i, j, starcount, count;

    fgPrintf( FG_ASTRO, FG_INFO, "Initializing stars\n");

    if ( FG_STAR_LEVELS < 4 ) {
	fgPrintf( FG_ASTRO, FG_EXIT, "Big whups in stars.cxx\n");
    }

    // build the full path name to the stars data base file
    string path = current_options.get_fg_root() + "/Astro/stars" + ".gz";

    fgPrintf( FG_ASTRO, FG_INFO, "  Loading stars from %s\n", path.c_str() );

    fg_gzifstream in( path );
    if ( ! in )
	fgPrintf( FG_ASTRO, FG_EXIT,
		  "Cannot open star file: '%s'\n", path.c_str() );

    starcount = 0;

    StopWatch timer;
    timer.start();

    // read in each line of the file
    while ( ! in.eof() && starcount < FG_MAX_STARS )
    {
	in.eat_comments();
	string name;
	char c = 0;
	getline( in.stream(), name, ',' );
	in.stream() >> starlist[starcount].x >> c;
	in.stream() >> starlist[starcount].y >> c;
	// in.stream() >> starlist[starcount].x; in.get(c);
	// in.stream() >> starlist[starcount].y; in.get(c);
	in.stream() >> starlist[starcount].z;
	++starcount;
    }

    timer.stop();
    cerr << "Loaded " << starcount << " stars in "
	 << timer.elapsedSeconds() << " seconds" << endl;

    min_magnitude[0] = 4.2;
    min_magnitude[1] = 3.6;
    min_magnitude[2] = 3.0;
    min_magnitude[3] = 2.4;
    min_magnitude[4] = 1.8;
    min_magnitude[5] = 1.2;
    min_magnitude[6] = 0.6;
    min_magnitude[7] = 0.0;

    // build the various star display lists
    for ( i = 0; i < FG_STAR_LEVELS; i++ ) {

	stars[i] = xglGenLists(1);
	xglNewList( stars[i], GL_COMPILE );
	xglBegin( GL_POINTS );

	count = 0;

	for ( j = 0; j < starcount; j++ ) {
	    magnitude = starlist[j].z;
	    // printf("magnitude = %.2f\n", magnitude);

	    if ( magnitude < min_magnitude[i] ) {
		right_ascension = starlist[j].x;
		declination = starlist[j].y;

		count++;

		// 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) * 0.042);
		  
		magnitude = magnitude * 0.9 + 
		    (((FG_STAR_LEVELS - 1) - i) * 0.014);
		// 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) );
	    }
	} // while

	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();
	    
	fgPrintf( FG_ASTRO, FG_INFO,
		  "  Loading %d stars brighter than %.2f\n", 
		  count, min_magnitude[i]);
    }

    return 1;  // OK, we got here because initialization worked.
}


// Draw the Stars
void fgStarsRender( void ) {
    fgFLIGHT *f;
    fgVIEW *v;
    fgLIGHT *l;
    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 + 10.0 * DEG_TO_RAD ) ) {
	    i = 0;
	} else if ( l->sun_angle > (FG_PI_2 + 8.8 * DEG_TO_RAD ) ) {
	    i = 1;
	} else if ( l->sun_angle > (FG_PI_2 + 7.5 * DEG_TO_RAD ) ) {
	    i = 2;
	} else if ( l->sun_angle > (FG_PI_2 + 7.0 * DEG_TO_RAD ) ) {
	    i = 3;
	} else if ( l->sun_angle > (FG_PI_2 + 6.5 * DEG_TO_RAD ) ) {
	    i = 4;
	} else if ( l->sun_angle > (FG_PI_2 + 6.0 * DEG_TO_RAD ) ) {
	    i = 5;
	} else if ( l->sun_angle > (FG_PI_2 + 5.5 * DEG_TO_RAD ) ) {
	    i = 6;
	} else {
	    i = 7;
	}

	// printf("RENDERING STARS = %d (night)\n", i);

	xglCallList(stars[i]);
    } else {
	// printf("not RENDERING STARS (day)\n");
    }
}


// $Log$
// Revision 1.17  1998/09/24 15:36:19  curt
// Converted to c++ style comments.
//
// Revision 1.16  1998/09/24 15:25:24  curt
// Miscellaneous tweaks.
//
//
// Revision 1.15  1998/09/17 18:25:12  curt
// Fixed output message.
//
// Revision 1.14  1998/09/15 04:26:22  curt
// New textured moon and rewritten/restructured Astro code contributed by Durk
// Talsma.
//
// Revision 1.13  1998/09/01 19:03:04  curt
// Changes contributed by Bernie Bright <bbright@c031.aone.net.au>
//  - The new classes in libmisc.tgz define a stream interface into zlib.
//    I've put these in a new directory, Lib/Misc.  Feel free to rename it
//    to something more appropriate.  However you'll have to change the
//    include directives in all the other files.  Additionally you'll have
//    add the library to Lib/Makefile.am and Simulator/Main/Makefile.am.
//
//    The StopWatch class in Lib/Misc requires a HAVE_GETRUSAGE autoconf
//    test so I've included the required changes in config.tgz.
//
//    There are a fair few changes to Simulator/Objects as I've moved
//    things around.  Loading tiles is quicker but thats not where the delay
//    is.  Tile loading takes a few tenths of a second per file on a P200
//    but it seems to be the post-processing that leads to a noticeable
//    blip in framerate.  I suppose its time to start profiling to see where
//    the delays are.
//
//    I've included a brief description of each archives contents.
//
// Lib/Misc/
//   zfstream.cxx
//   zfstream.hxx
//     C++ stream interface into zlib.
//     Taken from zlib-1.1.3/contrib/iostream/.
//     Minor mods for STL compatibility.
//     There's no copyright associated with these so I assume they're
//     covered by zlib's.
//
//   fgstream.cxx
//   fgstream.hxx
//     FlightGear input stream using gz_ifstream.  Tries to open the
//     given filename.  If that fails then filename is examined and a
//     ".gz" suffix is removed or appended and that file is opened.
//
//   stopwatch.hxx
//     A simple timer for benchmarking.  Not used in production code.
//     Taken from the Blitz++ project.  Covered by GPL.
//
//   strutils.cxx
//   strutils.hxx
//     Some simple string manipulation routines.
//
// Simulator/Airports/
//   Load airports database using fgstream.
//   Changed fgAIRPORTS to use set<> instead of map<>.
//   Added bool fgAIRPORTS::search() as a neater way doing the lookup.
//   Returns true if found.
//
// Simulator/Astro/
//   Modified fgStarsInit() to load stars database using fgstream.
//
// Simulator/Objects/
//   Modified fgObjLoad() to use fgstream.
//   Modified fgMATERIAL_MGR::load_lib() to use fgstream.
//   Many changes to fgMATERIAL.
//   Some changes to fgFRAGMENT but I forget what!
//
// Revision 1.12  1998/08/27 17:02:01  curt
// Contributions from Bernie Bright <bbright@c031.aone.net.au>
// - use strings for fg_root and airport_id and added methods to return
//   them as strings,
// - inlined all access methods,
// - made the parsing functions private methods,
// - deleted some unused functions.
// - propogated some of these changes out a bit further.
//
// Revision 1.11  1998/08/25 20:53:29  curt
// Shuffled $FG_ROOT file layout.
//
// Revision 1.10  1998/08/10 20:33:09  curt
// Rewrote star loading and rendering to:
//   1. significantly improve load speed
//   2. transition from no stars to stars through eight stages.
//
// Revision 1.9  1998/08/06 12:45:20  curt
// Modified to bring in stars in 8 increments based on magnitude, not number
// of stars.
//
// Revision 1.8  1998/07/13 21:00:10  curt
// Wrote access functions for current fgOPTIONS.
//
// Revision 1.7  1998/05/29 20:35:42  curt
// Added zlib support for reading in compressed data files.
//
// Revision 1.6  1998/05/13 18:25:35  curt
// Root path info moved to fgOPTIONS.
//
// Revision 1.5  1998/04/28 01:19:03  curt
// Type-ified fgTIME and fgVIEW
//
// 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 00:45:03  curt
// Wrapped "#include <config.h>" in "#ifdef HAVE_CONFIG_H"
// Fixed a bug when generating sky colors.
//
// Revision 1.1  1998/04/22 13:21:34  curt
// C++ - ifing the code a bit.
//
// Revision 1.11  1998/04/18 04:13:58  curt
// Moved fg_debug.c to it's own library.
//
// Revision 1.10  1998/04/03 21:52:51  curt
// Converting to Gnu autoconf system.
//
// Revision 1.9  1998/03/14 00:27:12  curt
// Updated fgGENERAL to a "type" of struct.
//
// Revision 1.8  1998/02/12 21:59:38  curt
// Incorporated code changes contributed by Charlie Hotchkiss
// <chotchkiss@namg.us.anritsu.com>
//
// Revision 1.7  1998/02/09 15:07:48  curt
// Minor tweaks.
//
// Revision 1.6  1998/02/02 20:53:23  curt
// To version 0.29
//
// Revision 1.5  1998/01/27 18:35:53  curt
// Minor tweaks.
//
// Revision 1.4  1998/01/27 00:47:49  curt
// Incorporated Paul Bleisch's <pbleisch@acm.org> new debug message
// system and commandline/config file processing code.
//
// Revision 1.3  1998/01/19 19:26:59  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 1.24  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.