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
