--- /dev/null
+/**************************************************************************
+ * areautils.c -- support routines to handle dynamic management of scenery areas
+ *
+ * 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)
+ **************************************************************************/
+
+
+#ifdef WIN32
+# include <windows.h>
+#endif
+
+#include <GL/glut.h>
+#include "../XGL/xgl.h"
+
+#include <math.h>
+
+#include "areautils.h"
+#include "../Include/constants.h"
+
+
+/* Generate the unique scenery area 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 area 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) */
+static long gen_index(struct bucket *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 area index and find the lon, lat, x, and y */
+static void parse_index(long int index, struct bucket *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 area index */
+static void gen_path(long int index, char *path) {
+ struct bucket p;
+ int top_lon, top_lat, main_lon, main_lat;
+ char hem, pole;
+
+ parse_index(index, &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;
+ main_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;
+ main_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/%ld.ter",
+ hem, top_lon, pole, top_lat,
+ hem, main_lon, pole, main_lat,
+ index);
+}
+
+
+/* offset an bucket struct by the specified amounts in the X & Y direction */
+static void offset_bucket(struct bucket *in, struct bucket *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 area that it falls within */
+static void find_bucket(double lon, double lat, struct bucket *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 area index array */
+static void gen_idx_array(struct bucket *p1, long int *area,
+ int width, int height) {
+ struct bucket p2;
+ int dw, dh, i, j;
+
+ dh = height / 2;
+ dw = width / 2;
+ for ( j = 0; j < height; j++ ) {
+ for ( i = 0; i < width; i++ ) {
+ offset_bucket(p1, &p2, i - dw, j - dh);
+ area[(j*width)+i] = gen_index(&p2);
+ printf(" bucket = %d %d %d %d index = %ld\n",
+ p2.lon, p2.lat, p2.x, p2.y, area[(j*width)+i]);
+ }
+ }
+}
+
+
+int main() {
+ struct bucket p1;
+ long int area[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, area, 7, 7);
+ for ( j = 0; j < 7; j++ ) {
+ for ( i = 0; i < 7; i++ ) {
+ gen_path(area[(j*7)+i], path);
+ printf(" path = %s\n", path);
+ }
+ }
+
+ lon = 50.0;
+ lat = 50.0;
+ find_bucket(lon, lat, &p1);
+ gen_idx_array(&p1, area, 7, 7);
+ for ( j = 0; j < 7; j++ ) {
+ for ( i = 0; i < 7; i++ ) {
+ gen_path(area[(j*7)+i], path);
+ printf(" path = %s\n", path);
+ }
+ }
+
+ return(1);
+}
+
+
+/* $Log$
+/* Revision 1.1 1998/01/07 23:23:40 curt
+/* Initial revision.
+/*
+ * */
+
+
--- /dev/null
+/**************************************************************************
+ * areautils.h -- support routines to handle dynamic management of scenery areas
+ *
+ * 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)
+ **************************************************************************/
+
+
+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 area 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 area 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) */
+static long gen_index(struct bucket *p);
+
+
+/* Parse a unique scenery area index and find the lon, lat, x, and y */
+static void parse_index(long int index, struct bucket *p);
+
+
+/* Build a path name from an area index */
+static void gen_path(long int index, char *path);
+
+
+/* offset an bucket struct by the specified amounts in the X & Y direction */
+static void offset_bucket(struct bucket *in, struct bucket *out, int x, int y);
+
+
+/* Given a lat/lon, find the "bucket" or area that it falls within */
+static void find_bucket(double lon, double lat, struct bucket *p);
+
+
+/* Given a lat/lon, fill in the local area index array */
+static void gen_idx_array(struct bucket *p1, long int *area,
+ int width, int height);
+
+
+/* $Log$
+/* Revision 1.1 1998/01/07 23:23:40 curt
+/* Initial revision.
+/*
+ * */
+
+
projects / flightgear.git / commitdiff