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flightgear/Scenery/tileutils.h

101 lines
3 KiB
C

/**************************************************************************
* tileutils.h -- support routines to handle dynamic management of scenery tiles
*
* 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 TILEUTILS_H
#define TILEUTILS_H
struct bucket {
int lon; /* longitude (-180 to 179) */
int lat; /* latitude (-90 to 89) */
int x; /* x (0 to 7) */
int y; /* y (0 to 7) */
};
/* 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 gen_index(struct bucket *p);
/* Parse a unique scenery tile index and find the lon, lat, x, and y */
void parse_index(long int index, struct bucket *p);
/* Build a path name from an tile index */
void gen_base_path(struct bucket *p, char *path);
/* offset an bucket struct by the specified amounts in the X & Y direction */
void offset_bucket(struct bucket *in, struct bucket *out, int x, int y);
/* Given a lat/lon, find the "bucket" or tile that it falls within */
void find_bucket(double lon, double lat, struct bucket *p);
/* Given a lat/lon, fill in the local tile index array */
void gen_idx_array(struct bucket *p1, struct bucket *tiles,
int width, int height);
#endif /* TILEUTILS_H */
/* $Log$
/* 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.
*
* */