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, 22 insertions, 13 deletions

diff --git a/source/blender/blenkernel/intern/collision.c b/source/blender/blenkernel/intern/collision.c
index d21b527bbd6..2f80fbbec46 100644
--- a/source/blender/blenkernel/intern/collision.c
+++ b/source/blender/blenkernel/intern/collision.c
@@ -47,6 +47,7 @@
 
 #include "BKE_cloth.h"
 #include "BKE_effect.h"
+#include "BKE_group.h"
 #include "BKE_layer.h"
 #include "BKE_modifier.h"
 #include "BKE_scene.h"
@@ -502,12 +503,14 @@ static void add_collision_object(Object ***objs, unsigned int *numobj, unsigned
 
 	/* objects in dupli groups, one level only for now */
 	if (ob->dup_group && level == 0) {
-		GroupObject *go;
 		Group *group= ob->dup_group;
 
 		/* add objects */
-		for (go= group->gobject.first; go; go= go->next)
-			add_collision_object(objs, numobj, maxobj, go->ob, self, level+1, modifier_type);
+		FOREACH_GROUP_OBJECT(group, object)
+		{
+			add_collision_object(objs, numobj, maxobj, object, self, level+1, modifier_type);
+		}
+		FOREACH_GROUP_OBJECT_END
 	}
 }
 
@@ -515,9 +518,7 @@ static void add_collision_object(Object ***objs, unsigned int *numobj, unsigned
 // collision object will exclude self 
 Object **get_collisionobjects_ext(Scene *scene, Object *self, Group *group, unsigned int *numcollobj, unsigned int modifier_type, bool dupli)
 {
-	Base *base;
 	Object **objs;
-	GroupObject *go;
 	unsigned int numobj= 0, maxobj= 100;
 	int level = dupli ? 0 : 1;
 	
@@ -526,11 +527,15 @@ Object **get_collisionobjects_ext(Scene *scene, Object *self, Group *group, unsi
 	/* gather all collision objects */
 	if (group) {
 		/* use specified group */
-		for (go= group->gobject.first; go; go= go->next)
-			add_collision_object(&objs, &numobj, &maxobj, go->ob, self, level, modifier_type);
+		FOREACH_GROUP_OBJECT(group, object)
+		{
+			add_collision_object(&objs, &numobj, &maxobj, object, self, level, modifier_type);
+		}
+		FOREACH_GROUP_OBJECT_END
 	}
 	else {
 		Scene *sce_iter;
+		Base *base;
 		/* add objects in same layer in scene */
 		for (SETLOOPER(scene, sce_iter, base)) {
 			if ((base->flag & BASE_VISIBLED) != 0) {
@@ -576,24 +581,28 @@ static void add_collider_cache_object(ListBase **objs, Object *ob, Object *self,
 
 	/* objects in dupli groups, one level only for now */
 	if (ob->dup_group && level == 0) {
-		GroupObject *go;
 		Group *group= ob->dup_group;
 
 		/* add objects */
-		for (go= group->gobject.first; go; go= go->next)
-			add_collider_cache_object(objs, go->ob, self, level+1);
+		FOREACH_GROUP_OBJECT(group, object)
+		{
+			add_collider_cache_object(objs, object, self, level+1);
+		}
+		FOREACH_GROUP_OBJECT_END
 	}
 }
 
 ListBase *get_collider_cache(Scene *scene, Object *self, Group *group)
 {
-	GroupObject *go;
 	ListBase *objs= NULL;
 	
 	/* add object in same layer in scene */
 	if (group) {
-		for (go= group->gobject.first; go; go= go->next)
-			add_collider_cache_object(&objs, go->ob, self, 0);
+		FOREACH_GROUP_OBJECT(group, object)
+		{
+			add_collider_cache_object(&objs, object, self, 0);
+		}
+		FOREACH_GROUP_OBJECT_END
 	}
 	else {
 		Scene *sce_iter;