Render Layers and Collections (merge from render-layers)

Design Documents
----------------

* https://wiki.blender.org/index.php/Dev:2.8/Source/Layers

* https://wiki.blender.org/index.php/Dev:2.8/Source/DataDesignRevised

User Commit Log
---------------

* New Layer and Collection system to replace render layers and viewport layers.

* A layer is a set of collections of objects (and their drawing options) required for specific tasks.

* A collection is a set of objects, equivalent of the old layers in Blender. A collection can be shared across multiple layers.

* All Scenes have a master collection that all other collections are children of.

* New collection "context" tab (in Properties Editor)

* New temporary viewport "collections" panel to control per-collection
visibility

Missing User Features
---------------------

* Collection "Filter"
  Option to add objects based on their names

* Collection Manager operators
  The existing buttons  are placeholders

* Collection Manager drawing
  The editor main region is empty

* Collection Override

* Per-Collection engine settings
  This will come as a separate commit, as part of the clay-engine branch

Dev Commit Log
--------------

* New DNA file (DNA_layer_types.h) with the new structs
  We are replacing Base by a new extended Base while keeping it backward
  compatible with some legacy settings (i.e., lay, flag_legacy).

  Renamed all Base to BaseLegacy to make it clear the areas of code that
  still need to be converted

  Note: manual changes were required on - deg_builder_nodes.h, rna_object.c, KX_Light.cpp

* Unittesting for main syncronization requirements
  - read, write, add/copy/remove objects, copy scene, collection
  link/unlinking, context)

* New Editor: Collection Manager
  Based on patch by Julian Eisel
  This is extracted from the layer-manager branch. With the following changes:

    - Renamed references of layer manager to collections manager

    - I doesn't include the editors/space_collections/ draw and util files

    - The drawing code itself will be implemented separately by Julian

* Base / Object:
  A little note about them. Original Blender code would try to keep them
  in sync through the code, juggling flags back and forth. This will now
  be handled by Depsgraph, keeping Object and Bases more separated
  throughout the non-rendering code.

  Scene.base is being cleared in doversion, and the old viewport drawing
  code was poorly converted to use the new bases while the new viewport
  code doesn't get merged and replace the old one.

Python API Changes
------------------

```
- scene.layers
+ # no longer exists

- scene.objects
+ scene.scene_layers.active.objects

- scene.objects.active
+ scene.render_layers.active.objects.active

- bpy.context.scene.objects.link()
+ bpy.context.scene_collection.objects.link()

- bpy_extras.object_utils.object_data_add(context, obdata, operator=None, use_active_layer=True, name=None)
+ bpy_extras.object_utils.object_data_add(context, obdata, operator=None, name=None)

- bpy.context.object.select
+ bpy.context.object.select = True
+ bpy.context.object.select = False
+ bpy.context.object.select_get()
+ bpy.context.object.select_set(action='SELECT')
+ bpy.context.object.select_set(action='DESELECT')

-AddObjectHelper.layers
+ # no longer exists
```

1 files changed, 91 insertions, 0 deletions

diff --git a/source/blender/blenkernel/BKE_collection.h b/source/blender/blenkernel/BKE_collection.h
new file mode 100644
index 00000000000..c3f461dacd6
--- /dev/null
+++ b/source/blender/blenkernel/BKE_collection.h
@@ -0,0 +1,91 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Dalai Felinto
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#ifndef __BKE_COLLECTION_H__
+#define __BKE_COLLECTION_H__
+
+/** \file blender/blenkernel/BKE_collection.h
+ *  \ingroup bke
+ */
+
+#include "BLI_ghash.h"
+#include "BLI_iterator.h"
+#include "DNA_listBase.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Iterator;
+struct SceneCollection;
+struct Object;
+struct Base;
+struct Main;
+struct Scene;
+
+struct SceneCollection *BKE_collection_add(struct Scene *scene, struct SceneCollection *sc_parent, const char *name);
+bool BKE_collection_remove(struct Scene *scene, struct SceneCollection *sc);
+struct SceneCollection *BKE_collection_master(struct Scene *scene);
+void BKE_collection_master_free(struct Scene *scene);
+void BKE_collection_object_add(struct Scene *scene, struct SceneCollection *sc, struct Object *object);
+void BKE_collection_object_add_from(struct Scene *scene, struct Object *ob_src, struct Object *ob_dst);
+void BKE_collection_object_remove(struct Main *bmain, struct Scene *scene, struct SceneCollection *sc, struct Object *object, const bool free_us);
+void BKE_collections_object_remove(struct Main *bmain, struct Scene *scene, struct Object *object, const bool free_us);
+
+typedef void (*BKE_scene_objects_Cb)(struct Object *ob, void *data);
+typedef void (*BKE_scene_collections_Cb)(struct SceneCollection *ob, void *data);
+
+void BKE_scene_collections_callback(struct Scene *scene, BKE_scene_collections_Cb callback, void *data);
+void BKE_scene_objects_callback(struct Scene *scene, BKE_scene_objects_Cb callback, void *data);
+
+/* iterators */
+void BKE_scene_collections_Iterator_begin(struct Iterator *iter, void *data_in);
+void BKE_scene_collections_Iterator_next(struct Iterator *iter);
+void BKE_scene_collections_Iterator_end(struct Iterator *iter);
+
+void BKE_scene_objects_Iterator_begin(struct Iterator *iter, void *data_in);
+void BKE_scene_objects_Iterator_next(struct Iterator *iter);
+void BKE_scene_objects_Iterator_end(struct Iterator *iter);
+
+#define FOREACH_SCENE_COLLECTION(scene, _sc)                                  \
+	ITER_BEGIN(BKE_scene_collections_Iterator_begin,                          \
+	           BKE_scene_collections_Iterator_next,                           \
+	           BKE_scene_collections_Iterator_end,                            \
+	           scene, _sc)
+
+#define FOREACH_SCENE_COLLECTION_END                                          \
+	ITER_END
+
+#define FOREACH_SCENE_OBJECT(scene, _ob)                                      \
+	ITER_BEGIN(BKE_scene_objects_Iterator_begin,                              \
+	           BKE_scene_objects_Iterator_next,                               \
+	           BKE_scene_objects_Iterator_end,                                \
+	           scene, _ob)
+
+#define FOREACH_SCENE_OBJECT_END                                              \
+	ITER_END
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __BKE_COLLECTION_H__ */