Groups and collection: initial integration

Since we are ditching layers from Blender (2.8) we need a replacement to
control groups visibility. This commit introduces collections as the building
blocks for groups, allowing users to control visibility as well as overrides
for groups.

Features
========

* Groups now have collections
    This way you can change the visibility of a collection inside a group, and add
    overrides which are part of the group and are prioritized over other overrides.

* Outliner
    Groups can inspect their collections, change visibility, and add/remove members.

    To change an override of a group collection, you need to select an instance of
    the group, and then you can choose "group" in the collection properties editor
    to edit this group active collection instead of the view layer one.

* Dupli groups overrides
    We can now have multiple instances of the same group with an original "override"
    and different overrides depending on the collection the instanced object is part
    of.

Technical
=========

* Layers
    We use the same api for groups and scene as much as possible.

Reviewers: sergey (depsgraph), mont29 (read/write and user count)
Differential Revision: https://developer.blender.org/D2892

1 files changed, 21 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_group.h b/source/blender/blenkernel/BKE_group.h
index 1d35e6ab9fc..ac436876dc4 100644
--- a/source/blender/blenkernel/BKE_group.h
+++ b/source/blender/blenkernel/BKE_group.h
@@ -41,6 +41,7 @@ struct Object;
 struct Scene;
 
 void          BKE_group_free(struct Group *group);
+void          BKE_group_init(struct Group *group);
 struct Group *BKE_group_add(struct Main *bmain, const char *name);
 void          BKE_group_copy_data(struct Main *bmain, struct Group *group_dst, const struct Group *group_src, const int flag);
 struct Group *BKE_group_copy(struct Main *bmain, const struct Group *group);
@@ -54,4 +55,24 @@ bool          BKE_group_is_animated(struct Group *group, struct Object *parent);
 
 void          BKE_group_handle_recalc_and_update(const struct EvaluationContext *eval_ctx, struct Scene *scene, struct Object *parent, struct Group *group);
 
+#define FOREACH_GROUP_BASE(_group, _base)                         \
+	for (Base *_base = (Base *)(_group)->view_layer->object_bases.first; \
+	     _base;                                                   \
+		 _base = _base->next)                                     \
+	{
+
+#define FOREACH_GROUP_BASE_END                                    \
+	}
+
+#define FOREACH_GROUP_OBJECT(_group, _object)                     \
+	for (Base *_base = (Base *)(_group)->view_layer->object_bases.first; \
+	     _base;                                                   \
+		 _base = _base->next)                                     \
+	{                                                             \
+		Object *_object = _base->object;                          \
+		BLI_assert(_object != NULL);
+
+#define FOREACH_GROUP_OBJECT_END                                  \
+	}
+
 #endif  /* __BKE_GROUP_H__ */