LibOverride: Add initial support for adding new NLA tracks.

Also makes NLA tracks and strips overridable.

User can either edit existing strips in existing NLA tracks (but not add or remove them), and/or add new NLA tracks after those comming from the linked data.

Most of the work was as usual checking operators and adding protections against illegal operations in override context.

Note that since we can only rely on indices to deal with local added tracks, we forbid any local track being before any linked/original track.

Maniphest Tasks: T72629

Differential Revision: https://developer.blender.org/D9611

1 files changed, 67 insertions, 3 deletions

diff --git a/source/blender/makesrna/intern/rna_animation.c b/source/blender/makesrna/intern/rna_animation.c
index 0a9f2ff4819..10f86fe2671 100644
--- a/source/blender/makesrna/intern/rna_animation.c
+++ b/source/blender/makesrna/intern/rna_animation.c
@@ -587,7 +587,7 @@ static void rna_KeyingSet_paths_clear(KeyingSet *keyingset, ReportList *reports)
 /* needs wrapper function to push notifier */
 static NlaTrack *rna_NlaTrack_new(ID *id, AnimData *adt, Main *bmain, bContext *C, NlaTrack *track)
 {
-  NlaTrack *new_track = BKE_nlatrack_add(adt, track);
+  NlaTrack *new_track = BKE_nlatrack_add(adt, track, ID_IS_OVERRIDE_LIBRARY(id));
 
   WM_event_add_notifier(C, NC_ANIMATION | ND_NLA | NA_ADDED, NULL);
 
@@ -732,6 +732,60 @@ bool rna_AnimaData_override_apply(Main *UNUSED(bmain),
   return false;
 }
 
+bool rna_NLA_tracks_override_apply(Main *bmain,
+                                   PointerRNA *ptr_dst,
+                                   PointerRNA *ptr_src,
+                                   PointerRNA *UNUSED(ptr_storage),
+                                   PropertyRNA *UNUSED(prop_dst),
+                                   PropertyRNA *UNUSED(prop_src),
+                                   PropertyRNA *UNUSED(prop_storage),
+                                   const int UNUSED(len_dst),
+                                   const int UNUSED(len_src),
+                                   const int UNUSED(len_storage),
+                                   PointerRNA *UNUSED(ptr_item_dst),
+                                   PointerRNA *UNUSED(ptr_item_src),
+                                   PointerRNA *UNUSED(ptr_item_storage),
+                                   IDOverrideLibraryPropertyOperation *opop)
+{
+  BLI_assert(opop->operation == IDOVERRIDE_LIBRARY_OP_INSERT_AFTER &&
+             "Unsupported RNA override operation on constraints collection");
+
+  AnimData *anim_data_dst = (AnimData *)ptr_dst->data;
+  AnimData *anim_data_src = (AnimData *)ptr_src->data;
+
+  /* Remember that insertion operations are defined and stored in correct order, which means that
+   * even if we insert several items in a row, we always insert first one, then second one, etc.
+   * So we should always find 'anchor' track in both _src *and* _dst. */
+  NlaTrack *nla_track_anchor = NULL;
+#  if 0
+  /* This is not working so well with index-based insertion, especially in case some tracks get
+   * added to lib linked data. So we simply add locale tracks at the end of the list always, order
+   * of override operations should ensure order of local tracks is preserved properly. */
+  if (opop->subitem_local_index >= 0) {
+    nla_track_anchor = BLI_findlink(&anim_data_dst->nla_tracks, opop->subitem_local_index);
+  }
+  /* Otherwise we just insert in first position. */
+#  else
+  nla_track_anchor = anim_data_dst->nla_tracks.last;
+#  endif
+
+  NlaTrack *nla_track_src = NULL;
+  if (opop->subitem_local_index >= 0) {
+    nla_track_src = BLI_findlink(&anim_data_src->nla_tracks, opop->subitem_local_index);
+  }
+  nla_track_src = nla_track_src ? nla_track_src->next : anim_data_src->nla_tracks.first;
+
+  BLI_assert(nla_track_src != NULL);
+
+  NlaTrack *nla_track_dst = BKE_nlatrack_copy(bmain, nla_track_src, true, 0);
+
+  /* This handles NULL anchor as expected by adding at head of list. */
+  BLI_insertlinkafter(&anim_data_dst->nla_tracks, nla_track_anchor, nla_track_dst);
+
+  // printf("%s: We inserted a NLA Track...\n", __func__);
+  return true;
+}
+
 #else
 
 /* helper function for Keying Set -> keying settings */
@@ -1251,14 +1305,19 @@ static void rna_def_animdata(BlenderRNA *brna)
   RNA_def_property_collection_sdna(prop, NULL, "nla_tracks", NULL);
   RNA_def_property_struct_type(prop, "NlaTrack");
   RNA_def_property_ui_text(prop, "NLA Tracks", "NLA Tracks (i.e. Animation Layers)");
+  RNA_def_property_override_flag(prop,
+                                 PROPOVERRIDE_OVERRIDABLE_LIBRARY |
+                                     PROPOVERRIDE_LIBRARY_INSERTION | PROPOVERRIDE_NO_PROP_NAME);
+  RNA_def_property_override_funcs(prop, NULL, NULL, "rna_NLA_tracks_override_apply");
 
   rna_api_animdata_nla_tracks(brna, prop);
 
+  RNA_define_lib_overridable(true);
+
   /* Active Action */
   prop = RNA_def_property(srna, "action", PROP_POINTER, PROP_NONE);
   /* this flag as well as the dynamic test must be defined for this to be editable... */
   RNA_def_property_flag(prop, PROP_EDITABLE | PROP_ID_REFCOUNT);
-  RNA_def_property_override_flag(prop, PROPOVERRIDE_OVERRIDABLE_LIBRARY);
   RNA_def_property_pointer_funcs(
       prop, NULL, "rna_AnimData_action_set", NULL, "rna_Action_id_poll");
   RNA_def_property_editable_func(prop, "rna_AnimData_action_editable");
@@ -1297,11 +1356,14 @@ static void rna_def_animdata(BlenderRNA *brna)
   prop = RNA_def_property(srna, "drivers", PROP_COLLECTION, PROP_NONE);
   RNA_def_property_collection_sdna(prop, NULL, "drivers", NULL);
   RNA_def_property_struct_type(prop, "FCurve");
-  RNA_def_property_override_flag(prop, PROPOVERRIDE_OVERRIDABLE_LIBRARY);
   RNA_def_property_ui_text(prop, "Drivers", "The Drivers/Expressions for this data-block");
 
+  RNA_define_lib_overridable(false);
+
   rna_api_animdata_drivers(brna, prop);
 
+  RNA_define_lib_overridable(true);
+
   /* General Settings */
   prop = RNA_def_property(srna, "use_nla", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_boolean_negative_sdna(prop, NULL, "flag", ADT_NLA_EVAL_OFF);
@@ -1322,6 +1384,8 @@ static void rna_def_animdata(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Pin in Graph Editor", "");
   RNA_def_property_update(prop, NC_ANIMATION | ND_ANIMCHAN | NA_EDITED, NULL);
 
+  RNA_define_lib_overridable(false);
+
   /* Animation Data API */
   RNA_api_animdata(srna);
 }