flightgear/src/ATC/towerlist.cxx

// towerlist.cxx -- ATC Tower data management class
//
// Written by David Luff, started March 2002.
// Based on navlist.cxx by Curtis Olson, started April 2000.
//
// Copyright (C) 2000  Curtis L. Olson - curt@flightgear.org
//
// 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.


#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <simgear/debug/logstream.hxx>
#include <simgear/misc/sgstream.hxx>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/math/sg_random.h>

#include "towerlist.hxx"

FGTowerList *current_towerlist;

// Constructor
FGTowerList::FGTowerList( void ) {
}


// Destructor
FGTowerList::~FGTowerList( void ) {
}


// load the navaids and build the map
bool FGTowerList::init( SGPath path ) {

    towerlist.erase( towerlist.begin(), towerlist.end() );

    sg_gzifstream in( path.str() );
    if ( !in.is_open() ) {
        SG_LOG( SG_GENERAL, SG_ALERT, "Cannot open file: " << path.str() );
        exit(-1);
    }

    // read in each line of the file

    in >> skipcomment;

#ifdef __MWERKS__
    char c = 0;
    while ( in.get(c) && c != '\0' ) {
        in.putback(c);
#else
    while ( !in.eof() ) {
#endif

	FGTower t;
        in >> t;
	if ( t.get_type() == '[' ) {
	    break;
	}

	//cout << "id = " << t.GetIdent() << endl;
	//cout << " type = " << t.get_type() << endl;
	//cout << " lon = " << t.get_lon() << endl;
	//cout << " lat = " << t.get_lat() << endl;
	//cout << " elev = " << t.get_elev() << endl;
	//cout << " freq = " << t.get_freq() << endl;
 	//cout << " range = " << t.get_range() << endl;

	towerlist[t.get_freq()].push_back(t);
        in >> skipcomment;
    }

    return true;
}


// query the database for the specified frequency, lon and lat are in
// degrees, elev is in meters
bool FGTowerList::query( double lon, double lat, double elev, double freq,
		       FGTower *t )
{
    lon *= SGD_DEGREES_TO_RADIANS;
    lat *= SGD_DEGREES_TO_RADIANS;
    //cout << "lon = " << lon << '\n';
    //cout << "lat = " << lat << '\n';
    //cout << "elev = " << elev << '\n';
    //cout << "freq = " << freq << '\n';

    tower_list_type stations = towerlist[(int)(freq*100.0 + 0.5)];

    tower_list_iterator current = stations.begin();
    tower_list_iterator last = stations.end();

    // double az1, az2, s;
    Point3D aircraft = sgGeodToCart( Point3D(lon, lat, elev) );
    Point3D station;
    double d;
    for ( ; current != last ; ++current ) {
	//cout << "testing " << current->GetIdent() << endl;
	station = Point3D(current->get_x(), current->get_y(), current->get_z());
	//cout << "aircraft = " << aircraft << endl;
	//cout << "station = " << station << endl;

	d = aircraft.distance3Dsquared( station );

	//cout << "  dist = " << sqrt(d)
	//     << "  range = " << current->get_range() * SG_NM_TO_METER << endl;

	// match up to twice the published range so we can model
	// reduced signal strength
	if ( d < (2 * current->get_range() * SG_NM_TO_METER 
		  * 2 * current->get_range() * SG_NM_TO_METER ) ) {
	    //cout << "matched = " << current->GetIdent() << endl;
	    *t = *current;
	    return true;
	}
    }

    return false;
}