Outliner visibility unification: Implement 3 levels of viewport visibility

Now collection and objects can be either:
* Disabled for all the view layers.
* Hidden for a view layer but not necessarily for all others.
* Visible for a view layer but not necessarily for all others.

Regarding icons: Whatever we decide to use for the "Hidden for all view
layers" needs to be a toggle-like icon. Because when viewing "Scenes"
instead of "View Layer" in the outliner we should be able to edit the
collection "Hidden for all the view layers" as an on/off option.

The operators are accessible via a Visibility context menu or shortcuts:
* Ctrl + Click: Isolate collection (use shift to extend).
* Alt + Click: Disable collection.
* Shift + Click: Hide/Show collection and its children (objects and collections)

Things yet to be tackled:
* Object outliner context menu can also get a Visibility sub-menu.
* Get better icons for viewport enable/disable.

Note:
* When using emulate 3 button mouse alt+click is used for 2d panning.
  In this case users have to use the operator from the menu.

See T57857 for discussion.

Patch: https://developer.blender.org/D4011
Reviewers: brecht and sergey

Thanks to the reviewers and William Reynish and Julien Kasper in
particular for the feedback.

3 files changed, 10 insertions, 20 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc
index 00981d75665..cc2d58dbe51 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes_view_layer.cc
@@ -64,11 +64,6 @@ void DepsgraphNodeBuilder::build_layer_collections(ListBase *lb)
 		COLLECTION_RESTRICT_VIEW : COLLECTION_RESTRICT_RENDER;
 
 	for (LayerCollection *lc = (LayerCollection *)lb->first; lc; lc = lc->next) {
-		if ((graph_->mode == DAG_EVAL_VIEWPORT) &&
-		    ((lc->flag & LAYER_COLLECTION_RESTRICT_VIEW) != 0))
-		{
-			continue;
-		}
 		if (lc->collection->flag & restrict_flag) {
 			continue;
 		}
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations_view_layer.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations_view_layer.cc
index 7f4a388718f..c0fe5243e58 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations_view_layer.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations_view_layer.cc
@@ -65,11 +65,6 @@ void DepsgraphRelationBuilder::build_layer_collections(ListBase *lb)
 		COLLECTION_RESTRICT_VIEW : COLLECTION_RESTRICT_RENDER;
 
 	for (LayerCollection *lc = (LayerCollection *)lb->first; lc; lc = lc->next) {
-		if ((graph_->mode == DAG_EVAL_VIEWPORT) &&
-		    ((lc->flag & LAYER_COLLECTION_RESTRICT_VIEW) != 0))
-		{
-			continue;
-		}
 		if ((lc->collection->flag & restrict_flag)) {
 			continue;
 		}
diff --git a/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc b/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc
index ff3128a2fb6..c705026b640 100644
--- a/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc
+++ b/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc
@@ -359,23 +359,23 @@ void scene_remove_unused_view_layers(const Depsgraph *depsgraph,
 	scene_cow->view_layers.last = view_layer_eval;
 }
 
-/* Makes it so given view layer only has bases corresponding to a visible
+/* Makes it so given view layer only has bases corresponding to enabled
  * objects. */
-void view_layer_remove_invisible_bases(const Depsgraph *depsgraph,
-                                       ViewLayer *view_layer)
+void view_layer_remove_disabled_bases(const Depsgraph *depsgraph,
+                                      ViewLayer *view_layer)
 {
-	const int base_visible_flag = (depsgraph->mode == DAG_EVAL_VIEWPORT) ?
+	const int base_enabled_flag = (depsgraph->mode == DAG_EVAL_VIEWPORT) ?
 		BASE_ENABLED_VIEWPORT : BASE_ENABLED_RENDER;
-	ListBase visible_bases = {NULL, NULL};
+	ListBase enabled_bases = {NULL, NULL};
 	for (Base *base = reinterpret_cast<Base *>(view_layer->object_bases.first),
 	          *base_next;
 	     base != NULL;
 	     base = base_next)
 	{
 		base_next = base->next;
-		const bool is_object_visible = (base->flag & base_visible_flag);
-		if (is_object_visible) {
-			BLI_addtail(&visible_bases, base);
+		const bool is_object_enabled = (base->flag & base_enabled_flag);
+		if (is_object_enabled) {
+			BLI_addtail(&enabled_bases, base);
 		}
 		else {
 			if (base == view_layer->basact) {
@@ -384,13 +384,13 @@ void view_layer_remove_invisible_bases(const Depsgraph *depsgraph,
 			MEM_freeN(base);
 		}
 	}
-	view_layer->object_bases = visible_bases;
+	view_layer->object_bases = enabled_bases;
 }
 
 void scene_cleanup_view_layers(const Depsgraph *depsgraph, Scene *scene_cow)
 {
 	scene_remove_unused_view_layers(depsgraph, scene_cow);
-	view_layer_remove_invisible_bases(
+	view_layer_remove_disabled_bases(
 	        depsgraph,
 	        reinterpret_cast<ViewLayer *>(scene_cow->view_layers.first));
 	/* TODO(sergey): Remove objects from collections as well.