Collections and groups unification

OVERVIEW

* In 2.7 terminology, all layers and groups are now collection datablocks.
* These collections are nestable, linkable, instanceable, overrideable, ..
  which opens up new ways to set up scenes and link + override data.
* Viewport/render visibility and selectability are now a part of the collection
  and shared across all view layers and linkable.
* View layers define which subset of the scene collection hierarchy is excluded
  for each. For many workflows one view layer can be used, these are more of an
  advanced feature now.

OUTLINER

* The outliner now has a "View Layer" display mode instead of "Collections",
  which can display the collections and/or objects in the view layer.
* In this display mode, collections can be excluded with the right click menu.
  These will then be greyed out and their objects will be excluded.
* To view collections not linked to any scene, the "Blender File" display mode
  can be used, with the new filtering option to just see Colleciton datablocks.
* The outliner right click menus for collections and objects were reorganized.
* Drag and drop still needs to be improved. Like before, dragging the icon or
  text gives different results, we'll unify this later.

LINKING AND OVERRIDES

* Collections can now be linked into the scene without creating an instance,
  with the link/append operator or from the collections view in the outliner.
* Collections can get static overrides with the right click menu in the outliner,
  but this is rather unreliable and not clearly communicated at the moment.
* We still need to improve the make override operator to turn collection instances
  into collections with overrides directly in the scene.

PERFORMANCE

* We tried to make performance not worse than before and improve it in some
  cases. The main thing that's still a bit slower is multiple scenes, we have to
  change the layer syncing to only updated affected scenes.
* Collections keep a list of their parent collections for faster incremental
  updates in syncing and caching.
* View layer bases are now in a object -> base hash to avoid quadratic time
  lookups internally and in API functions like visible_get().

VERSIONING

* Compatibility with 2.7 files should be improved due to the new visibility
  controls. Of course users may not want to set up their scenes differently
  now to avoid having separate layers and groups.
* Compatibility with 2.8 is mostly there, and was tested on Eevee demo and Hero
  files. There's a few things which are know to be not quite compatible, like
  nested layer collections inside groups.
* The versioning code for 2.8 files is quite complicated, and isolated behind
  #ifdef so it can be removed at the end of the release cycle.

KNOWN ISSUES

* The G-key group operators in the 3D viewport were left mostly as is, they
  need to be modified still to fit better.
* Same for the groups panel in the object properties. This needs to be updated
  still, or perhaps replaced by something better.
* Collections must all have a unique name. Less restrictive namespacing is to
  be done later, we'll have to see how important this is as all objects within
  the collections must also have a unique name anyway.
* Full scene copy and delete scene are exactly doing the right thing yet.

Differential Revision: https://developer.blender.org/D3383

https://code.blender.org/2018/05/collections-and-groups/

1 files changed, 38 insertions, 57 deletions

diff --git a/source/blender/blenkernel/intern/library_remap.c b/source/blender/blenkernel/intern/library_remap.c
index 983f6781572..cf2a001daaa 100644
--- a/source/blender/blenkernel/intern/library_remap.c
+++ b/source/blender/blenkernel/intern/library_remap.c
@@ -77,7 +77,6 @@
 #include "BKE_curve.h"
 #include "BKE_fcurve.h"
 #include "BKE_font.h"
-#include "BKE_group.h"
 #include "BKE_gpencil.h"
 #include "BKE_idprop.h"
 #include "BKE_image.h"
@@ -271,25 +270,27 @@ static void libblock_remap_data_preprocess_scene_object_unlink(
 		r_id_remap_data->skipped_refcounted++;
 	}
 	else {
-		BKE_collections_object_remove(r_id_remap_data->bmain, &sce->id, ob, false);
+		/* Remove object from all collections in the scene. free_use is false
+		 * to avoid recursively calling object free again. */
+		BKE_scene_collections_object_remove(r_id_remap_data->bmain, sce, ob, false);
 		if (!is_indirect) {
 			r_id_remap_data->status |= ID_REMAP_IS_LINKED_DIRECT;
 		}
 	}
 }
 
-static void libblock_remap_data_preprocess_group_unlink(
+static void libblock_remap_data_preprocess_collection_unlink(
         IDRemap *r_id_remap_data, Object *ob, const bool skip_indirect, const bool is_indirect)
 {
 	Main *bmain = r_id_remap_data->bmain;
-	for (Group *group = bmain->group.first; group; group = group->id.next) {
-		if (BKE_group_object_exists(group, ob)) {
+	for (Collection *collection = bmain->collection.first; collection; collection = collection->id.next) {
+		if (!BKE_collection_is_in_scene(collection) && BKE_collection_has_object(collection, ob)) {
 			if (skip_indirect && is_indirect) {
 				r_id_remap_data->skipped_indirect++;
 				r_id_remap_data->skipped_refcounted++;
 			}
 			else {
-				BKE_collections_object_remove(bmain, &group->id, ob, false);
+				BKE_collection_object_remove(bmain, collection, ob, false);
 				if (!is_indirect) {
 					r_id_remap_data->status |= ID_REMAP_IS_LINKED_DIRECT;
 				}
@@ -311,12 +312,14 @@ static void libblock_remap_data_preprocess(IDRemap *r_id_remap_data)
 
 				/* In case we are unlinking... */
 				if (!r_id_remap_data->old_id) {
+					/* TODO: how is it valid to iterator over a scene while
+					 * removing objects from it? can't this crash? */
 					/* ... everything from scene. */
 					FOREACH_SCENE_OBJECT_BEGIN(sce, ob_iter)
 					{
 						libblock_remap_data_preprocess_scene_object_unlink(
 						            r_id_remap_data, sce, ob_iter, skip_indirect, is_indirect);
-						libblock_remap_data_preprocess_group_unlink(
+						libblock_remap_data_preprocess_collection_unlink(
 						            r_id_remap_data, ob_iter, skip_indirect, is_indirect);
 					}
 					FOREACH_SCENE_OBJECT_END;
@@ -326,7 +329,7 @@ static void libblock_remap_data_preprocess(IDRemap *r_id_remap_data)
 					Object *old_ob = (Object *)r_id_remap_data->old_id;
 					libblock_remap_data_preprocess_scene_object_unlink(
 					            r_id_remap_data, sce, old_ob, skip_indirect, is_indirect);
-					libblock_remap_data_preprocess_group_unlink(
+					libblock_remap_data_preprocess_collection_unlink(
 					            r_id_remap_data, old_ob, skip_indirect, is_indirect);
 				}
 
@@ -360,23 +363,16 @@ static void libblock_remap_data_preprocess(IDRemap *r_id_remap_data)
 
 static void libblock_remap_data_postprocess_object_update(Main *bmain, Object *old_ob, Object *new_ob)
 {
-	if (old_ob->flag & OB_FROMGROUP) {
-		/* Note that for Scene's BaseObject->flag, either we:
-		 *     - unlinked old_ob (i.e. new_ob is NULL), in which case scenes' bases have been removed already.
-		 *     - remapped old_ob by new_ob, in which case scenes' bases are still valid as is.
-		 * So in any case, no need to update them here. */
-		if (BKE_group_object_find(NULL, old_ob) == NULL) {
-			old_ob->flag &= ~OB_FROMGROUP;
-		}
-		if (new_ob == NULL) {  /* We need to remove NULL-ified groupobjects... */
-			for (Group *group = bmain->group.first; group; group = group->id.next) {
-				BKE_group_object_unlink(group, NULL);
-			}
-		}
-		else {
-			new_ob->flag |= OB_FROMGROUP;
-		}
+	if (new_ob == NULL) {
+		 /* In case we unlinked old_ob (new_ob is NULL), the object has already
+		  * been removed from the scenes and their collections. We still have
+		  * to remove the NULL children from collections not used in any scene. */
+		BKE_collections_object_remove_nulls(bmain);
 	}
+	else {
+		BKE_main_collection_sync_remap(bmain);
+	}
+
 	if (old_ob->type == OB_MBALL) {
 		for (Object *ob = bmain->object.first; ob; ob = ob->id.next) {
 			if (ob->type == OB_MBALL && BKE_mball_is_basis_for(ob, old_ob)) {
@@ -386,27 +382,20 @@ static void libblock_remap_data_postprocess_object_update(Main *bmain, Object *o
 	}
 }
 
-static void libblock_remap_data_postprocess_group_scene_unlink(Main *UNUSED(bmain), Scene *sce, ID *old_id)
+static void libblock_remap_data_postprocess_collection_update(Main *bmain, Collection *old_collection, Collection *new_collection)
 {
-	/* Note that here we assume no object has no base (i.e. all objects are assumed instanced
-	 * in one scene...). */
-	FOREACH_SCENE_OBJECT_BEGIN(sce, ob)
-	{
-		if (ob->flag & OB_FROMGROUP) {
-			Group *grp = BKE_group_object_find(NULL, ob);
-
-			/* Unlinked group (old_id) is still in bmain... */
-			if (grp && (&grp->id == old_id || grp->id.us == 0)) {
-				grp = BKE_group_object_find(grp, ob);
-			}
-			if (!grp) {
-				ob->flag &= ~OB_FROMGROUP;
-			}
-		}
+	if (new_collection == NULL) {
+		 /* In case we unlinked old_collection (new_collection is NULL), we need
+		  * to remove any collection children that have been set to NULL in the
+		  * because of pointer replacement. */
+		BKE_collections_child_remove_nulls(bmain, old_collection);
+	}
+	else {
+		BKE_main_collection_sync_remap(bmain);
 	}
-	FOREACH_SCENE_OBJECT_END;
 }
 
+
 static void libblock_remap_data_postprocess_obdata_relink(Main *UNUSED(bmain), Object *ob, ID *new_id)
 {
 	if (ob->data == new_id) {
@@ -588,11 +577,7 @@ void BKE_libblock_remap_locked(
 			libblock_remap_data_postprocess_object_update(bmain, (Object *)old_id, (Object *)new_id);
 			break;
 		case ID_GR:
-			if (!new_id) {  /* Only affects us in case group was unlinked. */
-				for (Scene *sce = bmain->scene.first; sce; sce = sce->id.next) {
-					libblock_remap_data_postprocess_group_scene_unlink(bmain, sce, old_id);
-				}
-			}
+			libblock_remap_data_postprocess_collection_update(bmain, (Collection *)old_id, (Collection *)new_id);
 			break;
 		case ID_ME:
 		case ID_CU:
@@ -689,8 +674,6 @@ void BKE_libblock_relink_ex(
 	switch (GS(id->name)) {
 		case ID_SCE:
 		{
-			Scene *sce = (Scene *)id;
-
 			if (old_id) {
 				switch (GS(old_id->name)) {
 					case ID_OB:
@@ -699,21 +682,19 @@ void BKE_libblock_relink_ex(
 						break;
 					}
 					case ID_GR:
-						if (!new_id) {  /* Only affects us in case group was unlinked. */
-							libblock_remap_data_postprocess_group_scene_unlink(bmain, sce, old_id);
-						}
+						libblock_remap_data_postprocess_collection_update(bmain, (Collection *)old_id, (Collection *)new_id);
 						break;
 					default:
 						break;
 				}
 			}
 			else {
-				/* No choice but to check whole objects/groups. */
+				/* No choice but to check whole objects/collections. */
 				for (Object *ob = bmain->object.first; ob; ob = ob->id.next) {
 					libblock_remap_data_postprocess_object_update(bmain, ob, NULL);
 				}
-				for (Group *grp = bmain->group.first; grp; grp = grp->id.next) {
-					libblock_remap_data_postprocess_group_scene_unlink(bmain, sce, NULL);
+				for (Collection *collection = bmain->collection.first; collection; collection = collection->id.next) {
+					libblock_remap_data_postprocess_collection_update(bmain, collection, NULL);
 				}
 			}
 			break;
@@ -843,7 +824,7 @@ void BKE_libblock_free_datablock(ID *id, const int UNUSED(flag))
 			BKE_sound_free((bSound *)id);
 			break;
 		case ID_GR:
-			BKE_group_free((Group *)id);
+			BKE_collection_free((Collection *)id);
 			break;
 		case ID_AR:
 			BKE_armature_free((bArmature *)id);
@@ -1038,8 +1019,8 @@ void BKE_libblock_free_us(Main *bmain, void *idv)      /* test users */
 	
 	id_us_min(id);
 
-	/* XXX This is a temp (2.77) hack so that we keep same behavior as in 2.76 regarding groups when deleting an object.
-	 *     Since only 'user_one' usage of objects is groups, and only 'real user' usage of objects is scenes,
+	/* XXX This is a temp (2.77) hack so that we keep same behavior as in 2.76 regarding collections when deleting an object.
+	 *     Since only 'user_one' usage of objects is collections, and only 'real user' usage of objects is scenes,
 	 *     removing that 'user_one' tag when there is no more real (scene) users of an object ensures it gets
 	 *     fully unlinked.
 	 *     But only for local objects, not linked ones!