Fix T78193 (Rigify): use bone history tracking to find derived DEF bones.

It is not really safe to assume that by swapping ORG to DEF you will
get a deform bone derived from the given ORG bone. The new base rig
API already tracks copying of bones, so polish it up and use here.

Note however that this tracking doesn't work with bones created
without self.copy_bone, e.g. by legacy rigs.

1 files changed, 17 insertions, 0 deletions

diff --git a/rigify/utils/naming.py b/rigify/utils/naming.py
index e5c1c573..17d7496c 100644
--- a/rigify/utils/naming.py
+++ b/rigify/utils/naming.py
@@ -307,3 +307,20 @@ def random_id(length=8):
         text += random.choice(chars)
     text += str(hex(int(time.time())))[2:][-tlength:].rjust(tlength, '0')[::-1]
     return text
+
+
+def choose_derived_bone(generator, original, subtype, *, by_owner=True, recursive=True):
+    bones = generator.obj.pose.bones
+    names = generator.find_derived_bones(original, by_owner=by_owner, recursive=recursive)
+
+    direct = make_derived_name(original, subtype)
+    if direct in names and direct in bones:
+        return direct
+
+    prefix = _PREFIX_TABLE[subtype] + '-'
+    matching = [ name for name in names if name.startswith(prefix) and name in bones ]
+
+    if len(matching) > 0:
+        return matching[0]
+
+    return None