Scene building specific representation of a spatial node, which is a much
lighter subset of a full spatial node constructed and used for frame building
Defines the content of a spatial node. If the values in the descriptor don’t
change, that means the rest of the fields in a spatial node will end up with
the same result
The kind of a spatial node uid. These are required because we currently create external
nodes during DL building, but the internal nodes aren’t created until scene building.
TODO(gw): The internal scroll and reference frames are not used in any important way
Snap an offset to be incorporated into a transform, where the local space
may be considered the world space. We assume raster scale is 1.0, which
may not always be correct if there are intermediate surfaces used, however
those are either cases where snapping is not important (e.g. has perspective
or is not axis aligned), or an edge case (e.g. SVG filters) which we can accept
imperfection for now.