Rigify: support tags in SwitchParentBuilder for default selection.

Allow tagging parents with arbitrary strings to be later used
in selecting the best default parent for a child control.

Also add a tagged parent point at the limb IK control.

7 files changed, 28 insertions, 10 deletions

diff --git a/rigify/rigs/limbs/arm.py b/rigify/rigs/limbs/arm.py
index 98a3c50f..1ac979d0 100644
--- a/rigify/rigs/limbs/arm.py
+++ b/rigify/rigs/limbs/arm.py
@@ -62,7 +62,7 @@ class Rig(BaseLimbRig):
     def register_switch_parents(self, pbuilder):
         super().register_switch_parents(pbuilder)
 
-        pbuilder.register_parent(self, self.bones.org.main[2], exclude_self=True)
+        pbuilder.register_parent(self, self.bones.org.main[2], exclude_self=True, tags={'limb_end'})
 
     def make_ik_ctrl_widget(self, ctrl):
         create_hand_widget(self.obj, ctrl)
diff --git a/rigify/rigs/limbs/leg.py b/rigify/rigs/limbs/leg.py
index 35e68f58..99610a6a 100644
--- a/rigify/rigs/limbs/leg.py
+++ b/rigify/rigs/limbs/leg.py
@@ -145,7 +145,7 @@ class Rig(BaseLimbRig):
     def register_switch_parents(self, pbuilder):
         super().register_switch_parents(pbuilder)
 
-        pbuilder.register_parent(self, self.bones.org.main[2], exclude_self=True)
+        pbuilder.register_parent(self, self.bones.org.main[2], exclude_self=True, tags={'limb_end'})
 
     def make_ik_ctrl_widget(self, ctrl):
         obj = create_foot_widget(self.obj, ctrl)
diff --git a/rigify/rigs/limbs/limb_rigs.py b/rigify/rigs/limbs/limb_rigs.py
index 86fc6be4..dee9a6f4 100644
--- a/rigify/rigs/limbs/limb_rigs.py
+++ b/rigify/rigs/limbs/limb_rigs.py
@@ -375,6 +375,11 @@ class BaseLimbRig(BaseRig):
         if self.rig_parent_bone:
             pbuilder.register_parent(self, self.rig_parent_bone)
 
+        pbuilder.register_parent(
+            self, self.get_ik_control_output(), name=self.bones.ctrl.ik,
+            exclude_self=True, tags={'limb_ik'},
+        )
+
     def build_ik_parent_switch(self, pbuilder):
         ctrl = self.bones.ctrl
 
diff --git a/rigify/rigs/limbs/paw.py b/rigify/rigs/limbs/paw.py
index a13348d1..28374eec 100644
--- a/rigify/rigs/limbs/paw.py
+++ b/rigify/rigs/limbs/paw.py
@@ -107,7 +107,7 @@ class Rig(BaseLimbRig):
     def register_switch_parents(self, pbuilder):
         super().register_switch_parents(pbuilder)
 
-        pbuilder.register_parent(self, self.bones.org.main[3], exclude_self=True)
+        pbuilder.register_parent(self, self.bones.org.main[3], exclude_self=True, tags={'limb_end'})
 
     def make_ik_ctrl_widget(self, ctrl):
         create_foot_widget(self.obj, ctrl)
diff --git a/rigify/rigs/spines/spine_rigs.py b/rigify/rigs/spines/spine_rigs.py
index 9f62595a..25450717 100644
--- a/rigify/rigs/spines/spine_rigs.py
+++ b/rigify/rigs/spines/spine_rigs.py
@@ -99,7 +99,7 @@ class BaseSpineRig(TweakChainRig):
         org_parent = self.get_bone_parent(self.bones.org[0])
         parents = [org_parent] if org_parent else []
 
-        pbuilder.register_parent(self, self.get_master_control_output, name='Torso')
+        pbuilder.register_parent(self, self.get_master_control_output, name='Torso', tags={'torso'})
         pbuilder.build_child(
             self, master_name, exclude_self=True,
             extra_parents=parents, select_parent=org_parent,
@@ -110,8 +110,8 @@ class BaseSpineRig(TweakChainRig):
         self.register_parent_bones(pbuilder)
 
     def register_parent_bones(self, pbuilder):
-        pbuilder.register_parent(self, self.bones.org[0], name='Hips', exclude_self=True)
-        pbuilder.register_parent(self, self.bones.org[-1], name='Chest', exclude_self=True)
+        pbuilder.register_parent(self, self.bones.org[0], name='Hips', exclude_self=True, tags={'hips'})
+        pbuilder.register_parent(self, self.bones.org[-1], name='Chest', exclude_self=True, tags={'chest'})
 
     @stage.parent_bones
     def parent_master_control(self):
diff --git a/rigify/rigs/spines/super_head.py b/rigify/rigs/spines/super_head.py
index 9b85e5b5..65db79cc 100644
--- a/rigify/rigs/spines/super_head.py
+++ b/rigify/rigs/spines/super_head.py
@@ -322,7 +322,7 @@ class Rig(BaseHeadTailRig):
     def register_parent_bones(self):
         rig = self.rigify_parent or self
         builder = SwitchParentBuilder(self.generator)
-        builder.register_parent(rig, self.bones.org[-1], name='Head', exclude_self=True)
+        builder.register_parent(rig, self.bones.org[-1], name='Head', exclude_self=True, tags={'head'})
 
     @stage.configure_bones
     def configure_bbone_chain(self):
diff --git a/rigify/utils/switch_parent.py b/rigify/utils/switch_parent.py
index a0a6b0ea..bb2d9045 100644
--- a/rigify/utils/switch_parent.py
+++ b/rigify/utils/switch_parent.py
@@ -51,7 +51,7 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
     ##############################
     # API
 
-    def register_parent(self, rig, bone, *, name=None, is_global=False, exclude_self=False):
+    def register_parent(self, rig, bone, *, name=None, is_global=False, exclude_self=False, tags=None):
         """
         Registers a bone of the specified rig as a possible parent.
 
@@ -61,6 +61,7 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
           name              Name of the parent for mouse-over hint.
           is_global         The parent is accessible to all rigs, instead of just children of owner.
           exclude_self      The parent is invisible to the owner rig itself.
+          tags              Set of tags to use for default parent selection.
 
         Lazy creation:
           The bone parameter may be a function creating the bone on demand and
@@ -71,7 +72,7 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
         assert isinstance(bone, str) or callable(bone)
 
         entry = {
-            'rig': rig, 'bone': bone, 'name': name,
+            'rig': rig, 'bone': bone, 'name': name, 'tags': tags,
             'is_global': is_global, 'exclude_self': exclude_self, 'used': False,
         }
 
@@ -91,6 +92,7 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
           extra_parents     List of bone names or (name, user_name) pairs to use as additional parents.
           use_parent_mch    Create an intermediate MCH bone for the constraints and parent the child to it.
           select_parent     Select the specified bone instead of the last one.
+          select_tags       List of parent tags to try for default selection.
           ignore_global     Ignore the is_global flag of potential parents.
           exclude_self      Ignore parents registered by the rig itself.
           context_rig       Rig to use for selecting parents.
@@ -155,7 +157,8 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
     child_option_table = {
         'extra_parents': None,
         'prop_bone': None, 'prop_id': None, 'prop_name': None, 'controls': None,
-        'select_parent': None, 'ignore_global': False, 'exclude_self': False, 'context_rig': None,
+        'select_parent': None, 'ignore_global': False, 'exclude_self': False,
+        'context_rig': None, 'select_tags': None,
         'ctrl_bone': None,
         'no_fix_location': False, 'no_fix_rotation': False, 'no_fix_scale': False,
         'copy_location': None, 'copy_rotation': None, 'copy_scale': None,
@@ -243,10 +246,13 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
 
         # Build the final list of parent bone names
         parent_map = dict()
+        parent_tags = defaultdict(set)
 
         for parent in child['parents']:
             if parent['bone'] not in parent_map:
                 parent_map[parent['bone']] = parent['name']
+            if parent['tags']:
+                parent_tags[parent['bone']] |= parent['tags']
 
         last_main_parent_bone = child['parents'][-1]['bone']
         num_main_parents = len(parent_map.items())
@@ -262,6 +268,7 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
 
         # Find which bone to select
         select_bone = force_lazy(child['select_parent']) or last_main_parent_bone
+        select_tags = force_lazy(child['select_tags']) or []
         select_index = num_main_parents
 
         try:
@@ -269,6 +276,12 @@ class SwitchParentBuilder(GeneratorPlugin, MechanismUtilityMixin):
         except StopIteration:
             print("RIGIFY ERROR: Can't find bone '%s' to select as default parent of '%s'\n" % (select_bone, bone))
 
+        for tag in select_tags:
+            matching = [ i for i, (bone, _) in enumerate(parent_bones) if tag in parent_tags[bone] ]
+            if len(matching) > 0:
+                select_index = 1 + matching[-1]
+                break
+
         # Create the controlling property
         prop_bone = child['prop_bone'] = force_lazy(child['prop_bone']) or bone
         prop_name = child['prop_name'] or child['prop_id'] or 'Parent Switch'