Fix T75936: Alembic, allow exporting of invisible objects

Add a new depsgraph builder class that includes invisible objects and
use that in the Alembic exporter.

Alembic supports three options for visibility, "visible", "inherited",
and "hidden". This means that parents can be hidden and still have
visible children (contrary to USD, where invisibility is used to prune
an entire scene graph subtree). Because of this, the visibility is
stored on the transform node, as that represents the Object in Blender
and thus keeps the Alembic file as close to Blender's own structure as
possible.

Reviewed By: Sergey

Differential Revision: https://developer.blender.org/D8595

1 files changed, 2 insertions, 2 deletions

diff --git a/source/blender/io/common/intern/abstract_hierarchy_iterator.cc b/source/blender/io/common/intern/abstract_hierarchy_iterator.cc
index 93e7e677118..d825625cafc 100644
--- a/source/blender/io/common/intern/abstract_hierarchy_iterator.cc
+++ b/source/blender/io/common/intern/abstract_hierarchy_iterator.cc
@@ -80,7 +80,7 @@ void HierarchyContext::mark_as_not_instanced()
 
 bool HierarchyContext::is_object_visible(const enum eEvaluationMode evaluation_mode) const
 {
-  bool is_dupli = duplicator != nullptr;
+  const bool is_dupli = duplicator != nullptr;
   int base_flag;
 
   if (is_dupli) {
@@ -92,7 +92,7 @@ bool HierarchyContext::is_object_visible(const enum eEvaluationMode evaluation_m
     object->base_flag = duplicator->base_flag | BASE_FROM_DUPLI;
   }
 
-  int visibility = BKE_object_visibility(object, evaluation_mode);
+  const int visibility = BKE_object_visibility(object, evaluation_mode);
 
   if (is_dupli) {
     object->base_flag = base_flag;