Add-on: add support for the use_all_linked_data_direct option

Add support for Blender's `use_all_linked_data_direct` experimental
option. This is a workaround for an issue with BAT, for which a quick
solution is required by the Blender Studio (production crunch).

Flamenco writes the `.flamenco.blend` file with
`preferences.experimental.use_all_linked_data_direct` set to `True`, so
that BAT has an easier time finding linked assets.

CHANGELOG.md

@@ -11,6 +11,7 @@ bugs in actually-released versions.
 - Add-on: Do a "pre-submission check" before sending files to the farm. This should provide submission errors earlier in the process, without waiting for files to be collected.
 - Worker: better handling of long lines from Blender/FFmpeg, splitting them up at character boundaries.
 - Manager: change SQLite parameters to have write-through-log journalling and less filesystem synchronisation. This reduces I/O load on the Manager.
+- Add-on: Set Blender's experimental flag `use_all_linked_data_direct` to `True` on submitted files, to work around a shortcoming in BAT. See [Blender commit b8c7e93a6504](https://developer.blender.org/rBb8c7e93a6504833ee1e617523dfe2921c4fd0816) for the introduction of that flag.
 
 ## 3.1 - released 2022-10-18
 

addon/flamenco/operators.py

@@ -252,11 +252,15 @@ class FLAMENCO_OT_submit_job(FlamencoOpMixin, bpy.types.Operator):
         We can compress, since this file won't be managed by SVN and doesn't need diffability.
         """
         render = context.scene.render
+        prefs = context.preferences
 
         # Remember settings we need to restore after saving.
         old_use_file_extension = render.use_file_extension
         old_use_overwrite = render.use_overwrite
         old_use_placeholder = render.use_placeholder
+        old_use_all_linked_data_direct = getattr(
+            prefs.experimental, "use_all_linked_data_direct", None
+        )
 
         # TODO: see about disabling the denoiser (like the old Blender Cloud addon did).
 
@@ -269,6 +273,17 @@ class FLAMENCO_OT_submit_job(FlamencoOpMixin, bpy.types.Operator):
             render.use_overwrite = False
             render.use_placeholder = False
 
+            # To work around a shortcoming of BAT, ensure that all
+            # indirectly-linked data is still saved as directly-linked.
+            #
+            # See `133dde41bb5b: Improve handling of (in)direclty linked status
+            # for linked IDs` in Blender's Git repository.
+            if old_use_all_linked_data_direct is not None:
+                self.log.info(
+                    "Overriding prefs.experimental.use_all_linked_data_direct = True"
+                )
+                prefs.experimental.use_all_linked_data_direct = True
+
             filepath = Path(context.blend_data.filepath).with_suffix(".flamenco.blend")
             self.log.info("Saving copy to temporary file %s", filepath)
             bpy.ops.wm.save_as_mainfile(
@@ -281,6 +296,12 @@ class FLAMENCO_OT_submit_job(FlamencoOpMixin, bpy.types.Operator):
             render.use_overwrite = old_use_overwrite
             render.use_placeholder = old_use_placeholder
 
+            # Only restore if the property exists to begin with:
+            if old_use_all_linked_data_direct is not None:
+                prefs.experimental.use_all_linked_data_direct = (
+                    old_use_all_linked_data_direct
+                )
+
         return filepath
 
     def _submit_files(self, context: bpy.types.Context, blendfile: Path) -> set[str]: