newbucket.hxx

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/**************************************************************************
 * newbucket.hxx -- new bucket routines for better world modeling
 *
 * Written by Curtis L. Olson, started February 1999.
 *
 * Copyright (C) 1999  Curtis L. Olson - http://www.flightgear.org/~curt
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * $Id: newbucket_8hxx-source.html,v 1.17 2008/12/18 22:32:14 curt Exp $
 **************************************************************************/

#ifndef _NEWBUCKET_HXX
#define _NEWBUCKET_HXX

#include <simgear/compiler.h>
#include <simgear/constants.h>
#include <simgear/math/SGMath.hxx>

#include <cmath>
#include <cstdio> // sprintf()
#include <ostream>
#include <string>

#define SG_BUCKET_SPAN      0.125

#define SG_HALF_BUCKET_SPAN ( 0.5 * SG_BUCKET_SPAN )


// return the horizontal tile span factor based on latitude
static double sg_bucket_span( double l ) {
    if ( l >= 89.0 ) {
        return 360.0;
    } else if ( l >= 88.0 ) {
        return 8.0;
    } else if ( l >= 86.0 ) {
        return 4.0;
    } else if ( l >= 83.0 ) {
        return 2.0;
    } else if ( l >= 76.0 ) {
        return 1.0;
    } else if ( l >= 62.0 ) {
        return 0.5;
    } else if ( l >= 22.0 ) {
        return 0.25;
    } else if ( l >= -22.0 ) {
        return 0.125;
    } else if ( l >= -62.0 ) {
        return 0.25;
    } else if ( l >= -76.0 ) {
        return 0.5;
    } else if ( l >= -83.0 ) {
        return 1.0;
    } else if ( l >= -86.0 ) {
        return 2.0;
    } else if ( l >= -88.0 ) {
        return 4.0;
    } else if ( l >= -89.0 ) {
        return 8.0;
    } else {
        return 360.0;
    }
}


class SGBucket {

private:
    double cx, cy;  // centerpoint (lon, lat) in degrees of bucket
    short lon;        // longitude index (-180 to 179)
    short lat;        // latitude index (-90 to 89)
    char x;          // x subdivision (0 to 7)
    char y;          // y subdivision (0 to 7)

public:

    SGBucket();

    SGBucket(const double dlon, const double dlat);

    SGBucket(const SGGeod& geod);

    SGBucket(const bool is_good);

    SGBucket(const long int bindex);

    void set_bucket( double dlon, double dlat );

    void set_bucket( double *lonlat );

    void set_bucket(const SGGeod& geod);

    inline void make_bad() {
        set_bucket(0.0, 0.0);
        lon = -1000;
    }

    inline long int gen_index() const {
        return ((lon + 180) << 14) + ((lat + 90) << 6) + (y << 3) + x;
    }

    inline std::string gen_index_str() const {
        char tmp[20];
        std::sprintf(tmp, "%ld", 
                     (((long)lon + 180) << 14) + ((lat + 90) << 6)
                     + (y << 3) + x);
        return (std::string)tmp;
    }

    std::string gen_base_path() const;

    inline double get_center_lon() const {
        double span = sg_bucket_span( lat + y / 8.0 + SG_HALF_BUCKET_SPAN );

        if ( span >= 1.0 ) {
            return lon + span / 2.0;
        } else {
            return lon + x * span + span / 2.0;
        }
    }

    inline double get_center_lat() const {
        return lat + y / 8.0 + SG_HALF_BUCKET_SPAN;
    }

    double get_width() const;

    double get_height() const;

    double get_width_m() const; 

    double get_height_m() const;

    SGGeod get_center() const
    { return SGGeod::fromDeg(get_center_lon(), get_center_lat()); }

    SGGeod get_corner(unsigned num) const
    {
        double lonFac = ((num + 1) & 2) ? 0.5 : -0.5;
        double latFac = ((num    ) & 2) ? 0.5 : -0.5;
        return SGGeod::fromDeg(get_center_lon() + lonFac*get_width(),
                               get_center_lat() + latFac*get_height());
    }

    // Informational methods.

    inline int get_chunk_lon() const { return lon; }

    inline int get_chunk_lat() const { return lat; }

    inline int get_x() const { return x; }

    inline int get_y() const { return y; }

    // friends

    friend std::ostream& operator<< ( std::ostream&, const SGBucket& );
    friend bool operator== ( const SGBucket&, const SGBucket& );
};

inline bool operator!= (const SGBucket& lhs, const SGBucket& rhs)
    {
        return !(lhs == rhs);
    }


SGBucket sgBucketOffset( double dlon, double dlat, int x, int y );


void sgBucketDiff( const SGBucket& b1, const SGBucket& b2, int *dx, int *dy );


inline std::ostream&
operator<< ( std::ostream& out, const SGBucket& b )
{
    return out << b.lon << ":" << b.x << ", " << b.lat << ":" << b.y;
}


inline bool
operator== ( const SGBucket& b1, const SGBucket& b2 )
{
    return ( b1.lon == b2.lon &&
             b1.lat == b2.lat &&
             b1.x == b2.x &&
             b1.y == b2.y );
}


#endif // _NEWBUCKET_HXX

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