79 lines
2.4 KiB
C
79 lines
2.4 KiB
C
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/**************************************************************************
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* areautils.h -- support routines to handle dynamic management of scenery areas
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*
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* Written by Curtis Olson, started January 1998.
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*
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* Copyright (C) 1997 Curtis L. Olson - curt@infoplane.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* $Id$
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* (Log is kept at end of this file)
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**************************************************************************/
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struct bucket {
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int lon; /* longitude (-180 to 179) */
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int lat; /* latitude (-90 to 89) */
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int x; /* x (0 to 7) */
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int y; /* y (0 to 7) */
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};
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/* Generate the unique scenery area index containing the specified
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lon/lat parameters.
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The index is constructed as follows:
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9 bits - to represent 360 degrees of longitude (-180 to 179)
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8 bits - to represent 180 degrees of latitude (-90 to 89)
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Each 1 degree by 1 degree area is further broken down into an 8x8
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grid. So we also need:
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3 bits - to represent x (0 to 7)
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3 bits - to represent y (0 to 7) */
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static long gen_index(struct bucket *p);
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/* Parse a unique scenery area index and find the lon, lat, x, and y */
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static void parse_index(long int index, struct bucket *p);
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/* Build a path name from an area index */
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static void gen_path(long int index, char *path);
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/* offset an bucket struct by the specified amounts in the X & Y direction */
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static void offset_bucket(struct bucket *in, struct bucket *out, int x, int y);
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/* Given a lat/lon, find the "bucket" or area that it falls within */
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static void find_bucket(double lon, double lat, struct bucket *p);
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/* Given a lat/lon, fill in the local area index array */
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static void gen_idx_array(struct bucket *p1, long int *area,
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int width, int height);
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/* $Log$
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/* Revision 1.1 1998/01/07 23:23:40 curt
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/* Initial revision.
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/*
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* */
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