Depsgraph: fix handling of driver variable dependencies with proxies.

During driver var evaluation, the code directly skips to the proxy
object if present, so the dependencies should reflect that, instead
of inventing extra relations to pretend as if the values were
first copied from the proxy - they actually aren't.

The invented dependencies can't work without cycles in complex but
meaningful cases, e.g. drivers on armature data that depend on pose.

This alters the changes from 72cbf966fb91 to be more correct.

1 files changed, 21 insertions, 20 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index 8955e6c08eb..23856a59da3 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -1411,27 +1411,34 @@ void DepsgraphRelationBuilder::build_driver_variables(ID *id, FCurve *fcu)
   LISTBASE_FOREACH (DriverVar *, dvar, &driver->variables) {
     /* Only used targets. */
     DRIVER_TARGETS_USED_LOOPER_BEGIN (dvar) {
-      if (dtar->id == NULL) {
+      ID *target_id = dtar->id;
+      if (target_id == NULL) {
         continue;
       }
-      build_id(dtar->id);
-      build_driver_id_property(dtar->id, dtar->rna_path);
-      /* Initialize relations coming to proxy_from. */
-      Object *proxy_from = NULL;
-      if ((GS(dtar->id->name) == ID_OB) && (((Object *)dtar->id)->proxy_from != NULL)) {
-        proxy_from = ((Object *)dtar->id)->proxy_from;
-        build_id(&proxy_from->id);
+      build_id(target_id);
+      build_driver_id_property(target_id, dtar->rna_path);
+      /* Look up the proxy - matches dtar_id_ensure_proxy_from during evaluation. */
+      Object *object = NULL;
+      if (GS(target_id->name) == ID_OB) {
+        object = (Object *)target_id;
+        if (object->proxy_from != NULL) {
+          /* Redirect the target to the proxy, like in evaluation. */
+          object = object->proxy_from;
+          target_id = &object->id;
+          /* Prepare the redirected target. */
+          build_id(target_id);
+          build_driver_id_property(target_id, dtar->rna_path);
+        }
       }
       /* Special handling for directly-named bones. */
-      if ((dtar->flag & DTAR_FLAG_STRUCT_REF) && (((Object *)dtar->id)->type == OB_ARMATURE) &&
+      if ((dtar->flag & DTAR_FLAG_STRUCT_REF) && (object && object->type == OB_ARMATURE) &&
           (dtar->pchan_name[0])) {
-        Object *object = (Object *)dtar->id;
         bPoseChannel *target_pchan = BKE_pose_channel_find_name(object->pose, dtar->pchan_name);
         if (target_pchan == NULL) {
           continue;
         }
         OperationKey variable_key(
-            dtar->id, NodeType::BONE, target_pchan->name, OperationCode::BONE_DONE);
+            target_id, NodeType::BONE, target_pchan->name, OperationCode::BONE_DONE);
         if (is_same_bone_dependency(variable_key, self_key)) {
           continue;
         }
@@ -1439,17 +1446,17 @@ void DepsgraphRelationBuilder::build_driver_variables(ID *id, FCurve *fcu)
       }
       else if (dtar->flag & DTAR_FLAG_STRUCT_REF) {
         /* Get node associated with the object's transforms. */
-        if (dtar->id == id) {
+        if (target_id == id) {
           /* Ignore input dependency if we're driving properties of
            * the same ID, otherwise we'll be ending up in a cyclic
            * dependency here. */
           continue;
         }
-        OperationKey target_key(dtar->id, NodeType::TRANSFORM, OperationCode::TRANSFORM_FINAL);
+        OperationKey target_key(target_id, NodeType::TRANSFORM, OperationCode::TRANSFORM_FINAL);
         add_relation(target_key, driver_key, "Target -> Driver");
       }
       else if (dtar->rna_path != NULL && dtar->rna_path[0] != '\0') {
-        RNAPathKey variable_exit_key(dtar->id, dtar->rna_path, RNAPointerSource::EXIT);
+        RNAPathKey variable_exit_key(target_id, dtar->rna_path, RNAPointerSource::EXIT);
         if (RNA_pointer_is_null(&variable_exit_key.ptr)) {
           continue;
         }
@@ -1458,12 +1465,6 @@ void DepsgraphRelationBuilder::build_driver_variables(ID *id, FCurve *fcu)
           continue;
         }
         add_relation(variable_exit_key, driver_key, "RNA Target -> Driver");
-        if (proxy_from != NULL) {
-          RNAPathKey proxy_from_variable_key(
-              &proxy_from->id, dtar->rna_path, RNAPointerSource::EXIT);
-          RNAPathKey variable_entry_key(dtar->id, dtar->rna_path, RNAPointerSource::ENTRY);
-          add_relation(proxy_from_variable_key, variable_entry_key, "Proxy From -> Variable");
-        }
       }
       else {
         /* If rna_path is NULL, and DTAR_FLAG_STRUCT_REF isn't set, this