function during bulk index load from a feature iterator
Allows single-iteration of a source for dual purposes simultaneously,
e.g. doing other feature-based operations while still gaining the full
advantage of the bulk loaded spatial index without having to do multiple
feature iterations
nearest neighbor search based on QgsGeometry to QgsGeometries
Previously only point - geometry was possible. But with this
change, you can safely and accurately use QgsSpatialIndex
to determine the nearest neighbours between any types of
geometries.
This potentially avoids a second expensive feature request after
building a spatial index and later needing to re-request features
which match spatial index search.
It's non-default, as it requires the index to store all feature
geometries, so it's more memory expensive.
A very fast static spatial index for 2D points based on a flat KD-tree,
using https://github.com/mourner/kdbush.hpp
Compared to QgsSpatialIndex, this index:
- supports single point features only (no multipoints)
- is static (features cannot be added or removed from the index after construction)
- is much faster!
- supports true "distance based" searches, i.e. return all points within a radius
from a search point
