[Bf-blender-cvs] [8f050b6825b] blender-v2.83-release: Fix Cycles viewport render fully restarting after undo

[Brecht Van Lommel]

Commit: 8f050b6825b834fcdd48950f2aa3d5064f5a780c
Author: Brecht Van Lommel
Date:   Wed May 20 01:11:42 2020 +0200
Branches: blender-v2.83-release
https://developer.blender.org/rB8f050b6825b834fcdd48950f2aa3d5064f5a780c

Fix Cycles viewport render fully restarting after undo

With the optimized undo datablock pointers remain the same, so Cycles can now
update just the parts that changed.

===================================================================

M	source/blender/blenloader/intern/readfile.c

===================================================================

diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 56de45251a8..e1a08c0d4b1 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -8137,19 +8137,6 @@ static void lib_link_workspace_layout_restore(struct IDNameLib_Map *id_map,
 
           v3d->camera = restore_pointer_by_name(id_map, (ID *)v3d->camera, USER_REAL);
           v3d->ob_center = restore_pointer_by_name(id_map, (ID *)v3d->ob_center, USER_REAL);
-
-          /* Free render engines for now. */
-          ListBase *regionbase = (sl == area->spacedata.first) ? &area->regionbase :
-                                                                 &sl->regionbase;
-          for (region = regionbase->first; region; region = region->next) {
-            if (region->regiontype == RGN_TYPE_WINDOW) {
-              RegionView3D *rv3d = region->regiondata;
-              if (rv3d && rv3d->render_engine) {
-                RE_engine_free(rv3d->render_engine);
-                rv3d->render_engine = NULL;
-              }
-            }
-          }
         }
         else if (sl->spacetype == SPACE_GRAPH) {
           SpaceGraph *sipo = (SpaceGraph *)sl;