The new/experimental, layered `Animation` data-block is merged with the
existing `bAction` data-block.
The `Animation` data-block is considerably newer than `bAction`, so the
supporting code that was written for it is also more modern. When moving
that code into `bAction`, I chose to keep the modernity where possible,
and thus some of the old code has been updated as well. Things like
preferring references over pointers.
The `Animation` data-block is now gone from DNA, the main database, etc.
As this was still an experimental feature, there is no versioning code
to convert any of that to Actions.
The DNA struct `bAction` now has a C++ wrapper `animrig::Action`, that
can be obtained via `some_action->wrap()`.
`animrig::Action` has functions `is_empty()`, `is_action_legacy()`, and
`is_action_layered()`. They **all** return `true` when the Action is
empty, as in that case none of the data that makes an action either
'legacy' or 'layered' is there.
The 'animation filtering' code (for showing things in the dope sheet,
graph editor, etc) that I wrote for `Animation` is intentionally kept
around. These types now target 'layered actions' and the
already-existing ones 'legacy actions'. A future PR may merge these two
together, but given how much work it was to add something new there, I'd
rather wait until the dust has settled on this commit.
There are plenty of variables (and some comments) named `anim` or
`animation` that now are of type `animrig::Action`. I haven't renamed
them all, to keep the noise level low in this commit (it's already big
enough). This can be done in a followup, non-functional PR.
Related task: #121355
Pull Request: https://projects.blender.org/blender/blender/pulls/121357
Include Animation data-block handling in Blender's animation evaluation
stack. If an `Animation` is assigned to an `ID`, it will take precedence
over the NLA and/or any `Action` that might be assigned as well.
For more info, see #113594.
Pull Request: https://projects.blender.org/blender/blender/pulls/118677
