simgear/Bucket/bucketutils.h

// bucketutils.h -- support routines to handle fgBUCKET operations
//
// Written by Curtis Olson, started January 1998.
//
// 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)


#ifndef _BUCKETUTILS_H
#define _BUCKETUTILS_H


#ifdef __cplusplus                                                          
extern "C" {                            
#endif                                   


typedef struct {
    int lon;  // longitude (-180 to 179)
    int lat;  // latitude (-90 to 89)
    int x;    // x (0 to 7)
    int y;    // y (0 to 7)
} fgBUCKET;


/* Generate the unique scenery tile index containing the specified
   lon/lat parameters.

   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) */
long int fgBucketGenIndex( const fgBUCKET *p);


// Parse a unique scenery tile index and find the lon, lat, x, and y
void fgBucketParseIndex(long int index, fgBUCKET *p);


// Build a path name from an tile index
void fgBucketGenBasePath( const fgBUCKET *p, char *path);


// offset an bucket struct by the specified amounts in the X & Y direction
void fgBucketOffset(fgBUCKET *in, fgBUCKET *out, int x, int y);


// Given a lat/lon in degrees, find the "bucket" or tile that it falls
// within
void fgBucketFind(double lon, double lat, fgBUCKET *p);


// Given a lat/lon, fill in the local tile index array
void fgBucketGenIdxArray(fgBUCKET *p1, fgBUCKET *tiles, int width, int height);


#ifdef __cplusplus
}
#endif


#endif // _BUCKETUTILS_H


// $Log$
// Revision 1.4  1998/12/09 18:48:09  curt
// Use C++ style comments.
//
// Revision 1.3  1998/12/07 21:08:03  curt
// Added a const in a couple places to get rid of annoying compiler warnings.
//
// Revision 1.2  1998/07/04 00:46:48  curt
// typedef'd struct fgBUCKET.
//
// Revision 1.1  1998/04/08 23:28:59  curt
// Adopted Gnu automake/autoconf system.
//
// Revision 1.2  1998/01/24 00:03:28  curt
// Initial revision.
//
// Revision 1.1  1998/01/23 20:06:52  curt
// tileutils.* renamed to bucketutils.*
//
// Revision 1.6  1998/01/22 02:59:42  curt
// Changed #ifdef FILE_H to #ifdef _FILE_H
//
// Revision 1.5  1998/01/14 02:19:05  curt
// Makde offset_bucket visible to outside.
//
// Revision 1.4  1998/01/13 00:23:12  curt
// Initial changes to support loading and management of scenery tiles.  Note,
// there's still a fair amount of work left to be done.
//
// Revision 1.3  1998/01/10 00:01:48  curt
// Misc api changes and tweaks.
//
// Revision 1.2  1998/01/08 02:22:28  curt
// Continue working on basic features.
//
// Revision 1.1  1998/01/07 23:50:52  curt
// "area" renamed to "tile"
//
// Revision 1.1  1998/01/07 23:23:40  curt
// Initial revision.
//