Replace the IK_follow hack for not parenting bones to the root bone.

Instead of looking for a magic driver variable name, allow returning
an explicit list from the rig using the new dictionary return format.

Author: angavrilov

README

@@ -65,7 +65,8 @@ There is one final stage to rig generation.  Rigify checks all of the bones
 for "DEF-", "MCH-", and "ORG-" prefixes, and moves those bones to their own
 layers. It also sets all of the "DEF-" bones to deform, and sets all other
 bones to _not_ deform.  And finally, it looks for any bone that does not have
-a parent, and sets the root bone (which Rigify creates) as their parent.
+a parent, and sets the root bone (which Rigify creates) as their parent,
+with the exception of 'noparent_bones' described below.
 
 
 THE GUTS OF A RIG TYPE, BASIC
@@ -241,7 +242,7 @@ Implementation classes are shown in the metarig samples list and generate a samp
 GENERATING A PYTHON UI
 ----------------------
 The generate() method can also, optionally, return a dictionary with data
-used for generating the python UI. The dictionary may have the following
+mainly used for generating the python UI. The dictionary may have the following
 keys (all optional):
 
   'script': python code as list of strings.
@@ -264,6 +265,10 @@ keys (all optional):
 
     These are used in generating the register() and unregister() functions.
 
+  'noparent_bones': list of bone names.
+
+    These bones are not implicitly parented to the root bone if they have no parent.
+
 The 'utilities', 'imports' and 'register' lists returned by all rigs are concatenated
 and filtered for duplicates before use, in order to allow easy sharing of utility
 functions and classes: all that is needed is to ensure that shared code is included

generate.py

@@ -345,6 +345,7 @@ def generate_rig(context, metarig):
         ui_imports = UI_IMPORTS.copy()
         ui_utilities = UI_UTILITIES.copy()
         ui_register = UI_REGISTER.copy()
+        noparent_bones = []
         for rig in rigs:
             # Go into editmode in the rig armature
             bpy.ops.object.mode_set(mode='OBJECT')
@@ -361,6 +362,8 @@ def generate_rig(context, metarig):
                     ui_utilities += scripts['utilities']
                 if 'register' in scripts:
                     ui_register += scripts['register']
+                if 'noparent_bones' in scripts:
+                    noparent_bones += scripts['noparent_bones']
             elif scripts is not None:
                 ui_scripts += [scripts[0]]
         t.tick("Generate rigs: ")
@@ -381,25 +384,8 @@ def generate_rig(context, metarig):
     # Get a list of all the bones in the armature
     bones = [bone.name for bone in obj.data.bones]
 
-    # Parent any free-floating bones to the root excluding bones with child of constraint.
-    pbones = obj.pose.bones
-
-
-    ik_follow_drivers = []
-
-    if obj.animation_data:
-        for drv in obj.animation_data.drivers:
-            for var in drv.driver.variables:
-                if 'IK_follow' == var.name:
-                    ik_follow_drivers.append(drv.data_path)
-
-    noparent_bones = []
-    for bone in bones:
-        # if 'IK_follow' in pbones[bone].keys():
-        #     noparent_bones += [bone]
-        for d in ik_follow_drivers:
-            if bone in d:
-                noparent_bones += [bone]
+    # Parent any free-floating bones to the root excluding noparent_bones
+    noparent_bones = dict.fromkeys(noparent_bones)
 
     bpy.ops.object.mode_set(mode='EDIT')
     for bone in bones:

rigs/limbs/arm.py

@@ -1072,6 +1072,7 @@ def generate(self):
             'script': [script],
             'utilities': UTILITIES_RIG_ARM,
             'register': REGISTER_RIG_ARM,
+            'noparent_bones': [bones['ik']['mch_hand'][i] for i in [0,1]],
         }
 
 

rigs/limbs/leg.py

@@ -1395,6 +1395,7 @@ def generate(self):
             'script': [script],
             'utilities': UTILITIES_RIG_LEG,
             'register': REGISTER_RIG_LEG,
+            'noparent_bones': [bones['ik']['mch_foot'][i] for i in [0,1]],
         }
 
 

rigs/limbs/paw.py

@@ -1223,6 +1223,7 @@ def generate(self):
             'script': [script],
             'utilities': UTILITIES_RIG_LEG,
             'register': REGISTER_RIG_LEG,
+            'noparent_bones': [bones['ik']['mch_foot'][i] for i in [0,1]],
         }