Render: Use dependency graph for compositor/sequencer

This change makes it so a minimal dependency graph which only includes
compositor and sequencer is built for the render pipeline purposes.

Tricky part here is that it's only compositor itself and sequencer who
to use this dependency graph and IDs from it. Render engines are still
to be provided original IDs because:

- They will create dependency graph for the given scene, and currently
  it is not possible to create dependency graph from CoW scene.

- IDs from the compositor/sequencer dependency graph are "stripped",
  as in, they wouldn't have all view layers, collections or objects
	required for proper final render.

This creates annoying mess of mixing evaluated and original scene
access in various parts of the pipeline.

Fixes T63927: Compositing nodes - drivers don't really work

Reviewers: brecht

Maniphest Tasks: T63927

Differential Revision: https://developer.blender.org/D4911

1 files changed, 6 insertions, 0 deletions

diff --git a/source/blender/depsgraph/intern/depsgraph.h b/source/blender/depsgraph/intern/depsgraph.h
index 2dcbb6b5574..073ec99b3aa 100644
--- a/source/blender/depsgraph/intern/depsgraph.h
+++ b/source/blender/depsgraph/intern/depsgraph.h
@@ -194,6 +194,12 @@ struct Depsgraph {
 
   bool debug_is_evaluating;
 
+  /* Is set to truth for dependency graph which are used for post-processing (compositor and
+   * sequencer).
+   * Such dependency graph needs all view layers (so render pipeline can access names), but it
+   * does not need any bases. */
+  bool is_render_pipeline_depsgraph;
+
   /* Cached list of colliders/effectors for collections and the scene
    * created along with relations, for fast lookup during evaluation. */
   GHash *physics_relations[DEG_PHYSICS_RELATIONS_NUM];