A node in the hierarchy of coordinate system
transforms.
An id that identifies coordinate systems in the SpatialTree. Each
coordinate system has an id and those ids will be shared when the coordinates
system are the same or are in the same axis-aligned space. This allows
for optimizing mask generation.
The representation of the spatial tree during scene building, which is
mostly write-only, with a small number of queries for snapping,
picture cache building
Represents the spatial tree during frame building, which is mostly
read-only, apart from the tree update at the start of the frame
The delta updates to apply after building a new scene to the retained frame building
tree.