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Phil Cazzola:

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This is a minor bug fix for sgBucketDiff().
If you crossed the bucket size boundary, the answer for dx could be wrong.

E.g.
 going from   0:0, 21:7  to 0:7, 21:7   would give you dx = 7 (correct)
 but going from 0:0, 21:7 to 0:3, 22:0 would give you dx = 6 (instead of 7)

Previously it differenced the center longitudes of the buckets.  When you
cross a boundary, the center point of the larger bucket now lies on the edge of the smaller bucket.

The result was a dx with an integer + 1/2 bucket, which rint() was rounding to the nearest even int.

This function only seems to be used in TerraGear.
This commit is contained in:
ehofman
2005-05-01 08:50:39 +00:00
parent 3bd810fedc
commit dea7b9050d
1 changed files with 21 additions and 5 deletions
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26
simgear/bucket/newbucket.cxx
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@@ -271,16 +271,32 @@ void sgBucketDiff( const SGBucket& b1, const SGBucket& b2, int *dx, int *dy ) {
#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