Depsgraph: Allow building scene properties

This is used by driers and this is a first step towards support of
scenes used for only compositor or sequencer.

Fixes T61014: Assert adding a driver that uses a single property of a scene ID

1 files changed, 21 insertions, 5 deletions

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 2a76d5cd362..98c50bf6fdf 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
@@ -340,7 +340,15 @@ void scene_remove_unused_view_layers(const Depsgraph *depsgraph,
                                      const IDNode *id_node,
                                      Scene *scene_cow)
 {
-  const ViewLayer *view_layer_input = get_original_view_layer(depsgraph, id_node);
+  const ViewLayer *view_layer_input;
+  /* Indirectly linked scenes means it's not an input scene and not a set scene, and is pulled via
+   * some driver. Such scenes should not have view layers after copy. */
+  if (id_node->linked_state == DEG_ID_LINKED_INDIRECTLY) {
+    view_layer_input = NULL;
+  }
+  else {
+    view_layer_input = get_original_view_layer(depsgraph, id_node);
+  }
   ViewLayer *view_layer_eval = NULL;
   /* Find evaluated view layer. At the same time we free memory used by
    * all other of the view layers. */
@@ -349,16 +357,17 @@ void scene_remove_unused_view_layers(const Depsgraph *depsgraph,
        view_layer_cow != NULL;
        view_layer_cow = view_layer_next) {
     view_layer_next = view_layer_cow->next;
-    if (STREQ(view_layer_input->name, view_layer_cow->name)) {
+    if (view_layer_input != NULL && STREQ(view_layer_input->name, view_layer_cow->name)) {
       view_layer_eval = view_layer_cow;
     }
     else {
       BKE_view_layer_free_ex(view_layer_cow, false);
     }
   }
-  BLI_assert(view_layer_eval != NULL);
-  /* Make evaluated view layer the only one in the evaluated scene. */
-  view_layer_eval->prev = view_layer_eval->next = NULL;
+  /* Make evaluated view layer the only one in the evaluated scene (if it exists). */
+  if (view_layer_eval != NULL) {
+    view_layer_eval->prev = view_layer_eval->next = NULL;
+  }
   scene_cow->view_layers.first = view_layer_eval;
   scene_cow->view_layers.last = view_layer_eval;
 }
@@ -367,6 +376,9 @@ void scene_remove_unused_view_layers(const Depsgraph *depsgraph,
  * objects. */
 void view_layer_remove_disabled_bases(const Depsgraph *depsgraph, ViewLayer *view_layer)
 {
+  if (view_layer == NULL) {
+    return;
+  }
   ListBase enabled_bases = {NULL, NULL};
   LISTBASE_FOREACH_MUTABLE (Base *, base, &view_layer->object_bases) {
     /* TODO(sergey): Would be cool to optimize this somehow, or make it so
@@ -397,6 +409,10 @@ void view_layer_remove_disabled_bases(const Depsgraph *depsgraph, ViewLayer *vie
 void view_layer_update_orig_base_pointers(const ViewLayer *view_layer_orig,
                                           ViewLayer *view_layer_eval)
 {
+  if (view_layer_orig == NULL || view_layer_eval == NULL) {
+    /* Happens when scene is only used for parameters or compositor/sequencer. */
+    return;
+  }
   Base *base_orig = reinterpret_cast<Base *>(view_layer_orig->object_bases.first);
   LISTBASE_FOREACH (Base *, base_eval, &view_layer_eval->object_bases) {
     base_eval->base_orig = base_orig;