This patch implements the defocus node for the Realtime Compositor. The
implementation does not match the CPU compositor implementation, but
uses a new formulation that is more physically accurate and consistent
with Blender's render engines.
The existing CPU implementation is questionable starting from its circle
of confusion calculation, to the morphological operations applied on the
CoC radius, to ignoring the maximum CoC radius in the search kernel, and
ending with the threshold parameter used to reduce artifacts. Therefore,
it should be reimplemented along with this same implementation using a
more consistent methodology.
EEVEE and Workbench already have a GPU defocus method, which can be
ported to the compositor and used as the preview defocus algorithm.
While this implementation will be updated to be a more accurate method
that produces the same structure as the ported EEVEE implementation.
The new formulation ignores the threshold parameter for now, as well as
the preview parameter.
Pull Request: https://projects.blender.org/blender/blender/pulls/116391
e055db6605