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simgear/Bucket/newbucket.hxx
curt bc2ae82e81 Added some informational methods.
1999-03-12 22:51:18 +00:00

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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 - 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.
*
* $Id$
* (Log is kept at end of this file)
**************************************************************************/
#ifndef _NEWBUCKET_HXX
#define _NEWBUCKET_HXX
#include <Include/compiler.h>
#include STL_STRING
FG_USING_STD(string);
#include <stdio.h> // sprintf()
#include <Include/fg_constants.h>
#define FG_BUCKET_SPAN 0.125 // 1/8 of a degree
#define FG_HALF_BUCKET_SPAN 0.0625 // 1/2 of 1/8 of a degree = 1/16 = 0.0625
class FGBucket {
private:
double cx, cy; // centerpoint (lon, lat) in degrees of bucket
int lon; // longitude index (-180 to 179)
int lat; // latitude index (-90 to 89)
int x; // x subdivision (0 to 7)
int y; // y subdivision (0 to 7)
public:
// default constructor
FGBucket();
// create a bucket which would contain the specified lon/lat
FGBucket(const double lon, const double lat);
// create a bucket based on "long int" index
FGBucket(const long int bindex);
~FGBucket();
// Set the bucket params for the specified lat and lon
void set_bucket( double dlon, double dlat );
// Generate the unique scenery tile index for this bucket
long int gen_index();
// Build the path name for this bucket
string gen_base_path();
// return the center lon of a tile
double get_center_lon() const;
// return width of the tile
double get_width() const;
// return the center lat of a tile
double get_center_lat() const;
// return height of the tile
double get_height() const;
// Informational methods
inline int get_lon() const { return lon; }
inline int get_lat() const { return lat; }
inline int get_x() const { return x; }
inline int get_y() const { return y; }
// friends
friend ostream& operator<< ( ostream&, const FGBucket& );
friend bool operator== ( const FGBucket&, const FGBucket& );
};
// return the horizontal tile span factor based on latitude
inline double bucket_span( double l ) {
if ( l >= 89.0 ) {
return 0.0;
} 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 0.0;
}
}
// Set the bucket params for the specified lat and lon
inline void FGBucket::set_bucket( double dlon, double dlat ) {
//
// latitude first
//
double span = bucket_span( dlat );
double diff = dlon - (double)(int)dlon;
// cout << "diff = " << diff << " span = " << span << endl;
if ( (dlon >= 0) || (fabs(diff) < FG_EPSILON) ) {
lon = (int)dlon;
} else {
lon = (int)dlon - 1;
}
// find subdivision or super lon if needed
if ( span < FG_EPSILON ) {
// polar cap
lon = 0;
x = 0;
} else if ( span <= 1.0 ) {
x = (int)((dlon - lon) / span);
} else {
if ( (dlon >= 0) || (fabs(diff) < FG_EPSILON) ) {
lon = (int)( (int)(lon / span) * span);
} else {
// cout << " lon = " << lon
// << " tmp = " << (int)((lon-1) / span) << endl;
lon = (int)( (int)((lon + 1) / span) * span - span);
if ( lon < -180 ) {
lon = -180;
}
}
x = 0;
}
//
// then latitude
//
diff = dlat - (double)(int)dlat;
if ( (dlat >= 0) || (fabs(diff) < FG_EPSILON) ) {
lat = (int)dlat;
} else {
lat = (int)dlat - 1;
}
y = (int)((dlat - lat) * 8);
}
// default constructor
inline FGBucket::FGBucket() {}
// constructor for specified location
inline FGBucket::FGBucket(const double dlon, const double dlat) {
set_bucket(dlon, dlat);
}
// Parse a unique scenery tile index and find the lon, lat, x, and y
inline FGBucket::FGBucket(const long int bindex) {
long int index = bindex;
lon = index >> 14;
index -= lon << 14;
lon -= 180;
lat = index >> 6;
index -= lat << 6;
lat -= 90;
y = index >> 3;
index -= y << 3;
x = index;
}
// default destructor
inline FGBucket::~FGBucket() {}
// Generate the unique scenery tile index for this bucket
//
// The index is constructed as follows:
//
// 9 bits - to represent 360 degrees of longitude (-180 to 179)
// 8 bits - to represent 180 degrees of latitude (-90 to 89)
//
// Each 1 degree by 1 degree tile is further broken down into an 8x8
// grid. So we also need:
//
// 3 bits - to represent x (0 to 7)
// 3 bits - to represent y (0 to 7)
inline long int FGBucket::gen_index() {
return ((lon + 180) << 14) + ((lat + 90) << 6) + (y << 3) + x;
}
// return the center lon of a tile
inline double FGBucket::get_center_lon() const {
double span = bucket_span( lat + y / 8.0 + FG_HALF_BUCKET_SPAN );
if ( span >= 1.0 ) {
return lon + span / 2.0;
} else {
return lon + x * span + span / 2.0;
}
}
// return width of the tile
inline double FGBucket::get_width() const {
return bucket_span( get_center_lat() );
}
// return the center lat of a tile
inline double FGBucket::get_center_lat() const {
return lat + y / 8.0 + FG_HALF_BUCKET_SPAN;
}
// return height of the tile
inline double FGBucket::get_height() const {
return FG_BUCKET_SPAN;
}
// offset a bucket struct by the specified tile units in the X & Y
// direction
FGBucket fgBucketOffset( double dlon, double dlat, int x, int y );
// calculate the offset between two buckets
void fgBucketDiff( const FGBucket& b1, const FGBucket& b2, int *dx, int *dy );
/*
// Given a lat/lon, fill in the local tile index array
void fgBucketGenIdxArray(fgBUCKET *p1, fgBUCKET *tiles, int width, int height);
*/
inline ostream&
operator<< ( ostream& out, const FGBucket& b )
{
return out << b.lon << ":" << b.x << ", " << b.lat << ":" << b.y;
}
inline bool
operator== ( const FGBucket& b1, const FGBucket& b2 )
{
return ( b1.lon == b2.lon &&
b1.lat == b2.lat &&
b1.x == b2.x &&
b1.y == b2.y );
}
/*
inline string
fgBucketGenIndex( const fgBUCKET& p )
{
char index_str[256];
sprintf( index_str, "%ld", fgBucketGenIndex( &p ) );
return string( index_str );
}
*/
#endif // _NEWBUCKET_HXX
// $Log$
// Revision 1.5 1999/03/12 22:51:18 curt
// Added some informational methods.
//
// Revision 1.4 1999/03/02 01:01:43 curt
// Tweaks for compiling with native SGI compilers.
//
// Revision 1.3 1999/02/26 22:07:55 curt
// Added initial support for native SGI compilers.
//
// Revision 1.2 1999/02/11 01:09:34 curt
// Added a routine to calculate the offset in bucket units between two buckets.
//
// Revision 1.1 1999/02/08 23:52:16 curt
// Added a new "newbucket.[ch]xx" FGBucket class to replace the old
// fgBUCKET struct and C routines. This FGBucket class adjusts the tile
// width towards the poles to ensure the tiles are at least 8 miles wide.
//
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