Assets: Store Action sub-type in asset metadata

Blender 3.0 will only support single-frame Actions in the pose library.
The goal of this patch is to lay the groundwork for making it possible
for the Asset Browser to reject/hide "animation snippet" Action assets.

Determining whether an Action has one or more frames (i.e. whether it
has a single pose or animation) requires inspecting the Action itself,
and thus loading the data-block itself. This would make it impossible to
quickly determine from the asset browser.

To solve this, the Action is inspected before saving, and a
`"is_single_frame"` boolean (well, 0/1 integer) IDProperty is added.

Reviewed by: Severin

Differential Revision: https://developer.blender.org/D13202

1 files changed, 10 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_action.h b/source/blender/blenkernel/BKE_action.h
index 9f69c5e3976..db55daddba6 100644
--- a/source/blender/blenkernel/BKE_action.h
+++ b/source/blender/blenkernel/BKE_action.h
@@ -125,6 +125,16 @@ struct bActionGroup *BKE_action_group_find_name(struct bAction *act, const char
 /* Clear all 'temp' flags on all groups */
 void action_groups_clear_tempflags(struct bAction *act);
 
+/**
+ * Return whether the action has one unique point in time keyed.
+ *
+ * This is mostly for the pose library, which will have different behaviour depending on whether an
+ * Action corresponds to a "pose" (one keyframe) or "animation snippet" (multiple keyframes).
+ *
+ * \return `false` when there is no keyframe at all or keys on different points in time, `true`
+ * when exactly one point in time is keyed. */
+bool BKE_action_has_single_frame(const struct bAction *act);
+
 /* Pose API ----------------- */
 
 void BKE_pose_channel_free(struct bPoseChannel *pchan);