*
* Written by Curtis L. Olson, started February 1999.
*
- * Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
+ * Copyright (C) 1999 Curtis L. Olson - http://www.flightgear.org/~curt/
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
- * You should have received a copy of the GNU Library General Public
- * License along with this library; if not, write to the
- * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $Id$
**************************************************************************/
+#ifdef HAVE_CONFIG_H
+# include <simgear_config.h>
+#endif
+
#include <math.h>
#include <simgear/misc/sg_path.hxx>
set_bucket(dlon, dlat);
}
+SGBucket::SGBucket(const SGGeod& geod) {
+ set_bucket(geod);
+}
// create an impossible bucket if false
SGBucket::SGBucket(const bool is_good) {
}
-// default destructor
-SGBucket::~SGBucket() {
-}
-
-
// Set the bucket params for the specified lat and lon
void SGBucket::set_bucket( double *lonlat ) {
set_bucket( lonlat[0], lonlat[1] );
// cout << "diff = " << diff << " span = " << span << endl;
+ /* Calculate the greatest integral longitude less than
+ * or equal to the given longitude (floor(dlon)),
+ * but attribute coordinates near the east border
+ * to the next tile.
+ */
if ( (dlon >= 0) || (fabs(diff) < SG_EPSILON) ) {
lon = (int)dlon;
} else {
// find subdivision or super lon if needed
if ( span < SG_EPSILON ) {
+ /* sg_bucket_span() never returns 0.0
+ * or anything near it, so this really
+ * should not occur at any time.
+ */
// polar cap
lon = 0;
x = 0;
} else if ( span <= 1.0 ) {
+ /* We have more than one tile per degree of
+ * longitude, so we need an x offset.
+ */
x = (int)((dlon - lon) / span);
} else {
- if ( (dlon >= 0) || (fabs(diff) < SG_EPSILON) ) {
- lon = (int)( (int)(lon / span) * span);
- } else {
- // cout << " lon = " << lon
- // << " tmp = " << (int)((lon-1) / span) << endl;
- lon = (int)( (int)((lon + 1) / span) * span - span);
- if ( lon < -180 ) {
- lon = -180;
- }
- }
+ /* We have one or more degrees per tile,
+ * so we need to find the base longitude
+ * of that tile.
+ *
+ * First we calculate the integral base longitude
+ * (e.g. -85.5 => -86) and then find the greatest
+ * multiple of span that is less than or equal to
+ * that longitude.
+ *
+ * That way, the Greenwich Meridian is always
+ * a tile border.
+ *
+ * This gets us into trouble with the polar caps,
+ * which have width 360 and thus either span
+ * the range from 0 to 360 or from -360 to 0
+ * degrees, depending on whether lon is positive
+ * or negative!
+ *
+ * We also get into trouble with the 8 degree tiles
+ * north of 88N and south of 88S, because the west-
+ * and east-most tiles in that range will cover 184W
+ * to 176W and 176E to 184E respectively, with their
+ * center at 180E/W!
+ */
+ lon=(int)floor(floor((lon+SG_EPSILON)/span)*span);
+ /* Correct the polar cap issue */
+ if ( lon < -180 ) {
+ lon = -180;
+ }
x = 0;
}
//
diff = dlat - (double)(int)dlat;
+ /* Again, a modified floor() function (see longitude) */
if ( (dlat >= 0) || (fabs(diff) < SG_EPSILON) ) {
lat = (int)dlat;
} else {
lat = (int)dlat - 1;
}
+ /* Latitude base and offset are easier, as
+ * tiles always are 1/8 degree of latitude wide.
+ */
y = (int)((dlat - lat) * 8);
}
+void SGBucket::set_bucket(const SGGeod& geod)
+{
+ set_bucket(geod.getLongitudeDeg(), geod.getLatitudeDeg());
+}
+
// Build the path name for this bucket
-string SGBucket::gen_base_path() const {
+std::string SGBucket::gen_base_path() const {
// long int index;
int top_lon, top_lat, main_lon, main_lat;
char hem, pole;
// return width of the tile in degrees
double SGBucket::get_width() const {
+ if (lon==-180 && (lat==-89 || lat==88) ) {
+ /* Normally the tile at 180W in 88N and 89S
+ * would cover 184W to 176W and the next
+ * on the east side starts at 176W.
+ * To correct, make this a special tile
+ * from 180W to 176W with 4 degrees width
+ * instead of the normal 8 degrees at
+ * that latitude.
+ */
+ return 4.0;
+ }
return sg_bucket_span( get_center_lat() );
}
double clat_rad = clat * SGD_DEGREES_TO_RADIANS;
double cos_lat = cos( clat_rad );
double local_radius = cos_lat * SG_EQUATORIAL_RADIUS_M;
- double local_perimeter = 2.0 * local_radius * SGD_PI;
+ double local_perimeter = local_radius * SGD_2PI;
double degree_width = local_perimeter / 360.0;
- return sg_bucket_span( get_center_lat() ) * degree_width;
+ return get_width() * degree_width;
}
// return height of the tile in meters
double SGBucket::get_height_m() const {
- double perimeter = 2.0 * SG_EQUATORIAL_RADIUS_M * SGD_PI;
+ double perimeter = SG_EQUATORIAL_RADIUS_M * SGD_2PI;
double degree_height = perimeter / 360.0;
return SG_BUCKET_SPAN * degree_height;
#endif
// longitude difference
- double c1_lon = b1.get_center_lon();
- double c2_lon = b2.get_center_lon();
- double diff_lon = c2_lon - c1_lon;
- double span;
- if ( sg_bucket_span(c1_lat) <= sg_bucket_span(c2_lat) ) {
+ double diff_lon=0.0;
+ double span=0.0;
+
+ SGBucket tmp_bucket;
+ // To handle crossing the bucket size boundary
+ // we need to account for different size buckets.
+
+ if ( sg_bucket_span(c1_lat) <= sg_bucket_span(c2_lat) )
+ {
span = sg_bucket_span(c1_lat);
} else {
span = sg_bucket_span(c2_lat);
}
+ diff_lon = b2.get_center_lon() - b1.get_center_lon();
+
+ if (diff_lon <0.0)
+ {
+ diff_lon -= b1.get_width()*0.5 + b2.get_width()*0.5 - span;
+ }
+ else
+ {
+ diff_lon += b1.get_width()*0.5 + b2.get_width()*0.5 - span;
+ }
+
+
#ifdef HAVE_RINT
*dx = (int)rint( diff_lon / span );
#else
projects / simgear.git / blobdiff