1 /**************************************************************************
2 * newbucket.hxx -- new bucket routines for better world modeling
4 * Written by Curtis L. Olson, started February 1999.
6 * Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
8 * This library is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Library General Public
10 * License as published by the Free Software Foundation; either
11 * version 2 of the License, or (at your option) any later version.
13 * This library is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Library General Public License for more details.
18 * You should have received a copy of the GNU Library General Public
19 * License along with this library; if not, write to the
20 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
21 * Boston, MA 02111-1307, USA.
24 **************************************************************************/
34 #include <simgear/misc/sg_path.hxx>
36 #include "newbucket.hxx"
39 // default constructor
40 SGBucket::SGBucket() {
44 // constructor for specified location
45 SGBucket::SGBucket(const double dlon, const double dlat) {
46 set_bucket(dlon, dlat);
50 // create an impossible bucket if false
51 SGBucket::SGBucket(const bool is_good) {
59 // Parse a unique scenery tile index and find the lon, lat, x, and y
60 SGBucket::SGBucket(const long int bindex) {
61 long int index = bindex;
79 SGBucket::~SGBucket() {
83 // Set the bucket params for the specified lat and lon
84 void SGBucket::set_bucket( double *lonlat ) {
85 set_bucket( lonlat[0], lonlat[1] );
89 // Set the bucket params for the specified lat and lon
90 void SGBucket::set_bucket( double dlon, double dlat ) {
94 double span = sg_bucket_span( dlat );
95 double diff = dlon - (double)(int)dlon;
97 // cout << "diff = " << diff << " span = " << span << endl;
99 if ( (dlon >= 0) || (fabs(diff) < SG_EPSILON) ) {
105 // find subdivision or super lon if needed
106 if ( span < SG_EPSILON ) {
110 } else if ( span <= 1.0 ) {
111 x = (int)((dlon - lon) / span);
113 if ( (dlon >= 0) || (fabs(diff) < SG_EPSILON) ) {
114 lon = (int)( (int)(lon / span) * span);
116 // cout << " lon = " << lon
117 // << " tmp = " << (int)((lon-1) / span) << endl;
118 lon = (int)( (int)((lon + 1) / span) * span - span);
129 diff = dlat - (double)(int)dlat;
131 if ( (dlat >= 0) || (fabs(diff) < SG_EPSILON) ) {
136 y = (int)((dlat - lat) * 8);
140 // Build the path name for this bucket
141 string SGBucket::gen_base_path() const {
143 int top_lon, top_lat, main_lon, main_lat;
149 if ( (lon < 0) && (top_lon * 10 != lon) ) {
153 if ( top_lon >= 0 ) {
159 if ( main_lon < 0 ) {
165 if ( (lat < 0) && (top_lat * 10 != lat) ) {
169 if ( top_lat >= 0 ) {
175 if ( main_lat < 0 ) {
179 sprintf(raw_path, "%c%03d%c%02d/%c%03d%c%02d",
180 hem, top_lon, pole, top_lat,
181 hem, main_lon, pole, main_lat);
183 SGPath path( raw_path );
189 // return width of the tile in degrees
190 double SGBucket::get_width() const {
191 return sg_bucket_span( get_center_lat() );
195 // return height of the tile in degrees
196 double SGBucket::get_height() const {
197 return SG_BUCKET_SPAN;
201 // return width of the tile in meters
202 double SGBucket::get_width_m() const {
203 double clat = (int)get_center_lat();
205 clat = (int)clat + 0.5;
207 clat = (int)clat - 0.5;
209 double clat_rad = clat * SGD_DEGREES_TO_RADIANS;
210 double cos_lat = cos( clat_rad );
211 double local_radius = cos_lat * SG_EQUATORIAL_RADIUS_M;
212 double local_perimeter = 2.0 * local_radius * SGD_PI;
213 double degree_width = local_perimeter / 360.0;
215 return sg_bucket_span( get_center_lat() ) * degree_width;
219 // return height of the tile in meters
220 double SGBucket::get_height_m() const {
221 double perimeter = 2.0 * SG_EQUATORIAL_RADIUS_M * SGD_PI;
222 double degree_height = perimeter / 360.0;
224 return SG_BUCKET_SPAN * degree_height;
228 // find the bucket which is offset by the specified tile units in the
229 // X & Y direction. We need the current lon and lat to resolve
230 // ambiguities when going from a wider tile to a narrower one above or
231 // below. This assumes that we are feeding in
232 SGBucket sgBucketOffset( double dlon, double dlat, int dx, int dy ) {
233 SGBucket result( dlon, dlat );
234 double clat = result.get_center_lat() + dy * SG_BUCKET_SPAN;
236 // walk dy units in the lat direction
237 result.set_bucket( dlon, clat );
239 // find the lon span for the new latitude
240 double span = sg_bucket_span( clat );
242 // walk dx units in the lon direction
243 double tmp = dlon + dx * span;
244 while ( tmp < -180.0 ) {
247 while ( tmp >= 180.0 ) {
250 result.set_bucket( tmp, clat );
256 // calculate the offset between two buckets
257 void sgBucketDiff( const SGBucket& b1, const SGBucket& b2, int *dx, int *dy ) {
259 // Latitude difference
260 double c1_lat = b1.get_center_lat();
261 double c2_lat = b2.get_center_lat();
262 double diff_lat = c2_lat - c1_lat;
265 *dy = (int)rint( diff_lat / SG_BUCKET_SPAN );
267 if ( diff_lat > 0 ) {
268 *dy = (int)( diff_lat / SG_BUCKET_SPAN + 0.5 );
270 *dy = (int)( diff_lat / SG_BUCKET_SPAN - 0.5 );
274 // longitude difference
275 double c1_lon = b1.get_center_lon();
276 double c2_lon = b2.get_center_lon();
277 double diff_lon = c2_lon - c1_lon;
279 if ( sg_bucket_span(c1_lat) <= sg_bucket_span(c2_lat) ) {
280 span = sg_bucket_span(c1_lat);
282 span = sg_bucket_span(c2_lat);
286 *dx = (int)rint( diff_lon / span );
288 if ( diff_lon > 0 ) {
289 *dx = (int)( diff_lon / span + 0.5 );
291 *dx = (int)( diff_lon / span - 0.5 );