/************************************************************************** * bucketutils.c -- 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) **************************************************************************/ #include #include #include #include /* 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(struct fgBUCKET *p) { long index = 0; index = ((p->lon + 180) << 14) + ((p->lat + 90) << 6) + (p->y << 3) + p->x; /* printf(" generated index = %ld\n", index); */ return(index); } /* Parse a unique scenery tile index and find the lon, lat, x, and y */ void fgBucketParseIndex(long int index, struct fgBUCKET *p) { p->lon = index >> 14; index -= p->lon << 14; p->lon -= 180; p->lat = index >> 6; index -= p->lat << 6; p->lat -= 90; p->y = index >> 3; index -= p->y << 3; p->x = index; } /* Build a path name from an tile index */ void fgBucketGenBasePath(struct fgBUCKET *p, char *path) { long int index; int top_lon, top_lat, main_lon, main_lat; char hem, pole; index = fgBucketGenIndex(p); path[0] = '\0'; top_lon = p->lon / 10; main_lon = p->lon; if ( (p->lon < 0) && (top_lon * 10 != p->lon) ) { top_lon -= 1; } top_lon *= 10; if ( top_lon >= 0 ) { hem = 'e'; } else { hem = 'w'; top_lon *= -1; } if ( main_lon < 0 ) { main_lon *= -1; } top_lat = p->lat / 10; main_lat = p->lat; if ( (p->lat < 0) && (top_lat * 10 != p->lat) ) { top_lat -= 1; } top_lat *= 10; if ( top_lat >= 0 ) { pole = 'n'; } else { pole = 's'; top_lat *= -1; } if ( main_lat < 0 ) { main_lat *= -1; } sprintf(path, "%c%03d%c%03d/%c%03d%c%03d", hem, top_lon, pole, top_lat, hem, main_lon, pole, main_lat); } /* offset an bucket struct by the specified amounts in the X & Y direction */ void fgBucketOffset(struct fgBUCKET *in, struct fgBUCKET *out, int x, int y) { int diff, temp; int dist_lat; out->lon = in->lon; out->lat = in->lat; out->x = in->x; out->y = in->y; /* do X direction */ diff = out->x + x; /* printf(" reducing x (%d)\n", diff); */ if ( diff >= 0 ) { temp = diff / 8; } else if ( diff < -7 ) { temp = (diff + 1) / 8 - 1; } else { temp = diff / 8 - 1; } out->x = ((diff % 8) + 8) % 8; out->lon = ( (out->lon + 180 + 360 + temp) % 360 ) - 180; /* do Y direction */ diff = out->y + y; /* printf(" reducing x (%d)\n", diff); */ if ( diff >= 0 ) { temp = diff / 8; } else if ( diff < -7 ) { temp = (diff + 1) / 8 - 1; } else { temp = diff / 8 - 1; } out->y = ((diff % 8) + 8) % 8; out->lat = out->lat + temp; if ( out->lat >= 90 ) { dist_lat = out->lat - 90; /* printf(" +lat = %d +y = %d\n", dist_lat, out->y); */ out->lat = 90 - (dist_lat + 1); out->lon = ( (out->lon + 180 + 180) % 360 ) - 180; out->y = 7 - out->y; } if ( out->lat < -90 ) { dist_lat = -90 - out->lat; /* printf(" +lat = %d +y = %d\n", dist_lat, out->y); */ out->lat = -90 + (dist_lat - 1); out->lon = ( (out->lon + 180 + 180) % 360 ) - 180; out->y = 7 - out->y; } } /* Given a lat/lon, find the "bucket" or tile that it falls within */ void fgBucketFind(double lon, double lat, struct fgBUCKET *p) { double diff; diff = lon - (double)(int)lon; /* printf("diff = %.2f\n", diff); */ if ( (lon >= 0) || (fabs(diff) < FG_EPSILON) ) { p->lon = (int)lon; } else { p->lon = (int)lon - 1; } /* printf(" p->lon = %d\n", p->lon); */ diff = lat - (double)(int)lat; /* printf("diff = %.2f\n", diff); */ if ( (lat >= 0) || (fabs(diff) < FG_EPSILON) ) { p->lat = (int)lat; } else { p->lat = (int)lat - 1; } /* printf(" p->lat = %d\n", p->lat); */ p->x = (lon - p->lon) * 8; p->y = (lat - p->lat) * 8; printf("Bucket = lon,lat = %d,%d x,y index = %d,%d\n", p->lon, p->lat, p->x, p->y); } /* Given a lat/lon, fill in the local tile index array */ void fgBucketGenIdxArray(struct fgBUCKET *p1, struct fgBUCKET *tiles, int width, int height) { struct fgBUCKET *p2; int dw, dh, i, j; dh = height / 2; dw = width / 2; for ( j = 0; j < height; j++ ) { for ( i = 0; i < width; i++ ) { fgBucketOffset(p1, &tiles[(j*width)+i], i - dw, j - dh); p2 = &tiles[(j*width)+i]; printf(" bucket = %d %d %d %d index = %ld\n", p2->lon, p2->lat, p2->x, p2->y, fgBucketGenIndex(&tiles[(j*width)+i])); } } } /* sample main for testing int main() { struct fgBUCKET p1; long int tile[49]; char path[256]; double lon, lat; int i, j; p1.lon = 180; p1.lat = 90; p1.x = 7; p1.y = 7; printf("Max index = %ld\n", gen_index(&p1)); lon = -50.0; lat = -50.0; find_bucket(lon, lat, &p1); gen_idx_array(&p1, tile, 7, 7); for ( j = 0; j < 7; j++ ) { for ( i = 0; i < 7; i++ ) { gen_path(tile[(j*7)+i], path); printf(" path = %s\n", path); } } lon = 50.0; lat = 50.0; find_bucket(lon, lat, &p1); gen_idx_array(&p1, tile, 7, 7); for ( j = 0; j < 7; j++ ) { for ( i = 0; i < 7; i++ ) { gen_path(tile[(j*7)+i], path); printf(" path = %s\n", path); } } return(1); } */ /* $Log$ /* Revision 1.2 1998/01/24 00:03:28 curt /* Initial revision. /* * Revision 1.1 1998/01/23 20:06:51 curt * tileutils.* renamed to bucketutils.* * * Revision 1.6 1998/01/19 19:27:18 curt * Merged in make system changes from Bob Kuehne * This should simplify things tremendously. * * Revision 1.5 1998/01/14 02:19:04 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 00:01:47 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. * * */