/** \file newbucket.hxx
* A class and associated utiltity functions to manage world scenery tiling.
+ *
+ * Tile borders are aligned along circles of latitude and longitude.
+ * All tiles are 1/8 degree of latitude high and their width in degrees
+ * longitude depends on their latitude, adjusted in such a way that
+ * all tiles cover about the same amount of area of the earth surface.
*/
#ifndef _NEWBUCKET_HXX
#include <cstdio> // sprintf()
#include <ostream>
#include <string>
+#include <vector>
/**
* standard size of a bucket in degrees (1/8 of a degree)
// return the horizontal tile span factor based on latitude
static double sg_bucket_span( double l ) {
if ( l >= 89.0 ) {
- return 360.0;
- } else if ( l >= 88.0 ) {
- return 8.0;
+ return 12.0;
} else if ( l >= 86.0 ) {
return 4.0;
} else if ( l >= 83.0 ) {
return 1.0;
} else if ( l >= -86.0 ) {
return 2.0;
- } else if ( l >= -88.0 ) {
- return 4.0;
} else if ( l >= -89.0 ) {
- return 8.0;
+ return 4.0;
} else {
- return 360.0;
+ return 12.0;
}
}
class SGBucket {
private:
- double cx, cy; // centerpoint (lon, lat) in degrees of bucket
short lon; // longitude index (-180 to 179)
short lat; // latitude index (-90 to 89)
char x; // x subdivision (0 to 7)
double span = sg_bucket_span( lat + y / 8.0 + SG_HALF_BUCKET_SPAN );
if ( span >= 1.0 ) {
- return lon + span / 2.0;
+ return lon + get_width() / 2.0;
} else {
- return lon + x * span + span / 2.0;
+ return lon + x * span + get_width() / 2.0;
}
}
void sgBucketDiff( const SGBucket& b1, const SGBucket& b2, int *dx, int *dy );
+/**
+ * \relates SGBucket
+ * retrieve a list of buckets in the given bounding box
+ * @param min min lon,lat of bounding box in degrees
+ * @param max max lon,lat of bounding box in degrees
+ * @param list standard vector of buckets within the bounding box
+ */
+void sgGetBuckets( const SGGeod& min, const SGGeod& max, std::vector<SGBucket>& list );
+
/**
* Write the bucket lon, lat, x, and y to the output stream.
* @param out output stream
inline std::ostream&
operator<< ( std::ostream& out, const SGBucket& b )
{
- return out << b.lon << ":" << b.x << ", " << b.lat << ":" << b.y;
+ return out << b.lon << ":" << (int)b.x << ", " << b.lat << ":" << (int)b.y;
}