Previously when there was a single mesh/curve/point cloud/grease pencil
input, the code would still do a deep copy of the entire geometry. Not
only does this waste time and memory usage, it also inhibits the
benefits of the shared cache system, causing normals and other derived
data to be recalculated more than necessary.
This commit makes the realize instance node "free" in those cases.
When the instance has a non-identity transform it only copies and
transforms the positions; the rest of the geometry is untouched.
For the implementation it was simpler to still copy the ID data-block
and rely on implicit sharing to avoid the expense of copying attributes.
That's because we don't have access to the original geometry set
components after all the preprocessing has happened.
Pull Request: https://projects.blender.org/blender/blender/pulls/127867
079a8b395e