For an NLA strip to use a slotted Action, it needs to specify which slot
to use in that action. This is now handled by two new properties on the
strip in DNA & RNA: `action_slot_handle` and `action_slot_name`.
These serve the same purpose as their counterparts on the `AnimData`
struct.
Note that this commit does NOT add NLA evaluation support for slotted
Actions. It merely allows assigning them. Evaluation, tweak mode
support, etc. will be implemented in future commits.
Pull Request: https://projects.blender.org/blender/blender/pulls/127359
Fix linking & library-overriding with NLA Tweak Mode enabled. This is a
two-pronged approach:
- When linking an animated ID from a library file, and it happens to be
in NLA Tweak Mode, it is forced out of tweak mode. This ensures that
the correct Action is loaded, and that all the NLA flags are set
correctly to display the NLA animation (instead of only the tweaked
strip).
- For library overrides there is now a post-process step that runs after
all 'apply' functions have been run. This is necessary to ensure that
all the flags and pointers that NLA Tweak Mode depends on are actually
set correctly and consistently.
This also adds one utility function `BKE_nla_debug_print_flags()` that
is by now unused. It was very useful in debugging this, though, and I
think it'll be useful in the future as well.
Design task: #120573
Pull Request: https://projects.blender.org/blender/blender/pulls/120830
Seems to work OK in basic cases, but needs more work when copying
outside of Main at least.
Note: There is no behavioral changes expected from this commit.
Note that there are at least two known usecases for this change:
* Liboverrides, as with recursive resync and proxies conversion it
often ends up creating 'virtual' linked data that does not actually
exists in the library blend files.
* Complex versionning code (`do_versions_after_setup`) when it needs
to create new IDs (currently handling linked data that way is just not
supported!).
Implements #107847.
