Fix T78071: Drivers reading object visibility not updating automatically

A driver reading `Object.hide_viewport` would break when that object was
hidden. Hidden objects don't have the `OBJECT_BASE_FLAGS` node in the
depsgraph, but that node was required for the driver to work.

Now the `OBJECT_FROM_LAYER` component (which optionally contains the
`OBJECT_FROM_LAYER` node) has explicit `ENTRY` and `EXIT` nodes, which
are used for relations with other components. These relations now remain
valid, even when the `OBJECT_FROM_LAYER` node is absent.

Differential Revision: https://developer.blender.org/D8124

Reviewed By: sergey

1 files changed, 3 insertions, 0 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
index e0553182918..dbe3e310d72 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.h
@@ -168,6 +168,9 @@ class DepsgraphNodeBuilder : public DepsgraphBuilder {
   virtual void build_object_proxy_from(Object *object, bool is_object_visible);
   virtual void build_object_proxy_group(Object *object, bool is_object_visible);
   virtual void build_object_instance_collection(Object *object, bool is_object_visible);
+  virtual void build_object_from_layer(int base_index,
+                                       Object *object,
+                                       eDepsNode_LinkedState_Type linked_state);
   virtual void build_object_flags(int base_index,
                                   Object *object,
                                   eDepsNode_LinkedState_Type linked_state);