Armature: convert the length Python property of bones to a RNA property.

This allows accessing it from drivers and using it in UI, as
demonstrated by adding it to the transform panel of 3D View.

As an aside, properly mark transform-related properties of Bone
read-only, as they can only be changed correctly in edit mode.

1 files changed, 1 insertions, 1 deletions

diff --git a/source/blender/depsgraph/intern/builder/deg_builder_rna.cc b/source/blender/depsgraph/intern/builder/deg_builder_rna.cc
index d3ae3da9b56..e53ac40f196 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_rna.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_rna.cc
@@ -211,7 +211,7 @@ RNANodeIdentifier RNANodeQuery::construct_node_identifier(const PointerRNA *ptr,
         }
         /* Final transform properties go to the Done node for the exit. */
         else if (STREQ(prop_name, "head") || STREQ(prop_name, "tail") ||
-                 STRPREFIX(prop_name, "matrix")) {
+                 STREQ(prop_name, "length") || STRPREFIX(prop_name, "matrix")) {
           if (source == RNAPointerSource::EXIT) {
             node_identifier.operation_code = OperationCode::BONE_DONE;
           }