Rigify: new utilities for bone naming and driver creation, and some fixes.

- Added a utility for creating Transform Channel driver variables.
- Added a utility for deriving one bone name from another with suffix.

The bone name utility is inspired by get_bone_name from limb_utils.py

3 files changed, 56 insertions, 9 deletions

diff --git a/rigify/utils/bones.py b/rigify/utils/bones.py
index 9002d083..a8e55f9a 100644
--- a/rigify/utils/bones.py
+++ b/rigify/utils/bones.py
@@ -24,7 +24,7 @@ from mathutils import Vector, Matrix, Color
 from rna_prop_ui import rna_idprop_ui_prop_get
 
 from .errors import MetarigError
-from .naming import strip_org, make_mechanism_name, insert_before_lr
+from .naming import make_derived_name
 
 #=======================
 # Bone collection
@@ -256,8 +256,8 @@ def make_nonscaling_child(obj, bone_name, location, child_name_postfix=""):
 
     if obj == bpy.context.active_object and bpy.context.mode == 'EDIT_ARMATURE':
         # Create desired names for bones
-        name1 = make_mechanism_name(strip_org(insert_before_lr(bone_name, child_name_postfix + "_ns_ch")))
-        name2 = make_mechanism_name(strip_org(insert_before_lr(bone_name, child_name_postfix + "_ns_intr")))
+        name1 = make_derived_name(bone_name, 'mch', child_name_postfix + "_ns_ch")
+        name2 = make_derived_name(bone_name, 'mch', child_name_postfix + "_ns_intr")
 
         # Create bones
         child = copy_bone(obj, bone_name, name1)
diff --git a/rigify/utils/mechanism.py b/rigify/utils/mechanism.py
index 62d86154..ffec8a4c 100644
--- a/rigify/utils/mechanism.py
+++ b/rigify/utils/mechanism.py
@@ -52,8 +52,10 @@ def make_constraint(
     """
     con = owner.constraints.new(type)
 
-    if target is not None and subtarget is not None:
+    if target is not None and hasattr(con, 'target'):
         con.target = target
+
+    if subtarget is not None:
         con.subtarget = subtarget
 
     if space is not None:
@@ -130,10 +132,12 @@ def _init_driver_target(drv_target, var_info, target_id):
 
     else:
         # { 'id': ..., ... }
+        target_id = var_info.get('id', target_id)
+
         if target_id is not None:
             drv_target.id = target_id
 
-        for tp, tv in tdata.items():
+        for tp, tv in var_info.items():
             setattr(drv_target, tp, tv)
 
 
@@ -237,6 +241,29 @@ def make_driver(owner, prop, *, index=-1, type='SUM', expression=None, variables
 
     return fcu
 
+
+def driver_var_transform(target, bone=None, *, type='LOC_X', space='WORLD'):
+    """
+    Create a Transform Channel driver variable specification.
+
+    Usage:
+        make_driver(..., variables=[driver_var_transform(...)])
+    """
+
+    assert space in {'WORLD', 'TRANSFORM', 'LOCAL'}
+
+    target_map = {
+        'id': target,
+        'transform_type': type,
+        'transform_space': space + '_SPACE',
+    }
+
+    if bone is not None:
+        target_map['bone_target'] = bone
+
+    return { 'type': 'TRANSFORMS', 'targets': [ target_map ] }
+
+
 #=============================================
 # Utility mixin
 #=============================================
diff --git a/rigify/utils/naming.py b/rigify/utils/naming.py
index 3af3d851..3983704a 100644
--- a/rigify/utils/naming.py
+++ b/rigify/utils/naming.py
@@ -37,6 +37,10 @@ def strip_trailing_number(s):
     return s[0:-4] if m else s
 
 
+def strip_prefix(name):
+    return re.sub(r'^(?:ORG|MCH|DEF)-', '', name)
+
+
 def unique_name(collection, base_name):
     base_name = strip_trailing_number(base_name)
     count = 1
@@ -116,11 +120,27 @@ def deformer(name):
 make_deformer_name = deformer
 
 
+_prefix_functions = { 'org': org, 'mch': mch, 'def': deformer, 'ctrl': lambda x: x }
+
+
 def insert_before_lr(name, text):
-    if name[-1] in ['l', 'L', 'r', 'R'] and name[-2] in ['.', '-', '_']:
-        return name[:-2] + text + name[-2:]
-    else:
-        return name + text
+    name_parts = re.match(r'^(.*?)((?:[._-][lLrR](?:\.\d+)?)?)$', name)
+    name_base, name_suffix = name_parts.groups()
+    return name_base + text + name_suffix
+
+
+def make_derived_name(name, subtype, suffix=None):
+    """ Replaces the name prefix, and optionally adds the suffix (before .LR if found).
+    """
+    assert(subtype in _prefix_functions)
+
+    name = strip_prefix(name)
+
+    if suffix:
+        name = insert_before_lr(name, suffix)
+
+    return _prefix_functions[subtype](name)
+
 
 def random_id(length=8):
     """ Generates a random alphanumeric id string.