From ce358e2313a23002b546955e334db2a0bf507e7f Mon Sep 17 00:00:00 2001
From: Peter Sadrozinski <psadrozinski@gmail.com>
Date: Sat, 7 May 2016 07:43:22 -0400
Subject: [PATCH] add siblings function to bucket. At some latitudes, buckets
can have multiple siblings.
---
simgear/bucket/newbucket.cxx | 48 ++++++++++++++++++++++++++++++++++++
simgear/bucket/newbucket.hxx | 5 ++++
2 files changed, 53 insertions(+)
diff --git a/simgear/bucket/newbucket.cxx b/simgear/bucket/newbucket.cxx
index fb9a62a1..97b09490 100644
--- a/simgear/bucket/newbucket.cxx
+++ b/simgear/bucket/newbucket.cxx
@@ -286,6 +286,54 @@ double SGBucket::get_height_m() const {
return SG_BUCKET_SPAN * degree_height;
}
+unsigned int SGBucket::siblings( int dx, int dy, std::vector<SGBucket>& buckets ) const
+{
+ if (!isValid()) {
+ SG_LOG(SG_TERRAIN, SG_WARN, "SGBucket::sibling: requesting sibling of invalid bucket");
+ return 0;
+ }
+
+ double src_span = sg_bucket_span( get_center_lat() );
+
+ double clat = get_center_lat() + dy * SG_BUCKET_SPAN;
+ // return invalid here instead of clipping, so callers can discard
+ // invalid buckets without having to check if it's an existing one
+ if ((clat < -90.0) || (clat > 90.0)) {
+ return 0;
+ }
+
+ // find the lon span for the new latitude
+ double trg_span = sg_bucket_span( clat );
+
+ // if target span < src_span, return multiple buckets...
+ if ( trg_span < src_span ) {
+ // calc center longitude of westernmost sibling
+ double start_lon = get_center_lat() - src_span/2 + trg_span/2;
+
+ unsigned int num_buckets = src_span/trg_span;
+ for ( unsigned int x = 0; x < num_buckets; x++ ) {
+ double tmp = start_lon + x * trg_span;
+ tmp = SGMiscd::normalizePeriodic(-180.0, 180.0, tmp);
+
+ SGBucket b;
+ b.innerSet(tmp, clat);
+
+ buckets.push_back( b );
+ }
+ } else {
+ // just return the single sibling
+ double tmp = get_center_lon() + dx * trg_span;
+ tmp = SGMiscd::normalizePeriodic(-180.0, 180.0, tmp);
+
+ SGBucket b;
+ b.innerSet(tmp, clat);
+
+ buckets.push_back( b );
+ }
+
+ return buckets.size();
+}
+
SGBucket SGBucket::sibling(int dx, int dy) const
{
if (!isValid()) {
diff --git a/simgear/bucket/newbucket.hxx b/simgear/bucket/newbucket.hxx
index fe0bbbc4..e31c9935 100644
--- a/simgear/bucket/newbucket.hxx
+++ b/simgear/bucket/newbucket.hxx
@@ -288,6 +288,11 @@ public:
*/
SGBucket sibling(int dx, int dy) const;
+ /**
+ * @return multiple buckets offset from this by dx,dy
+ */
+ unsigned int siblings(int dz, int dy, std::vector<SGBucket>& buckets) const;
+
// friends
friend std::ostream& operator<< ( std::ostream&, const SGBucket& );
--
2.39.5