Rigify: added bend hinting to the arm and leg rigs.

This allows IK arms and legs to still function properly even when they
start with an entirely straight chain.

4 files changed, 74 insertions, 0 deletions

diff --git a/rigify/rigs/biped/arm/__init__.py b/rigify/rigs/biped/arm/__init__.py
index c09b39f4..93e757f4 100644
--- a/rigify/rigs/biped/arm/__init__.py
+++ b/rigify/rigs/biped/arm/__init__.py
@@ -96,6 +96,8 @@ class Rig:
         items = [('X', 'X', ''), ('Y', 'Y', ''), ('Z', 'Z', ''), ('-X', '-X', ''), ('-Y', '-Y', ''), ('-Z', '-Z', '')]
         group.primary_rotation_axis = bpy.props.EnumProperty(items=items, name="Primary Rotation Axis", default='X')
 
+        group.bend_hint = bpy.props.BoolProperty(name="Bend Hint", default=True, description="Give IK chain a hint about which way to bend.  Useful for perfectly straight chains.")
+
         group.separate_ik_layers = bpy.props.BoolProperty(name="Separate IK Control Layers:", default=False, description="Enable putting the ik controls on a separate layer from the fk controls.")
         group.ik_layers = bpy.props.BoolVectorProperty(size=32, description="Layers for the ik controls to be on.")
 
@@ -159,6 +161,9 @@ class Rig:
         r.label(text="Elbow rotation axis:")
         r.prop(params, "primary_rotation_axis", text="")
 
+        r = layout.row()
+        r.prop(params, "bend_hint")
+
         col = layout.column()
         col.prop(params, "use_upper_arm_twist")
         col.prop(params, "use_forearm_twist")
diff --git a/rigify/rigs/biped/arm/ik.py b/rigify/rigs/biped/arm/ik.py
index b16221d8..0ecf70e7 100644
--- a/rigify/rigs/biped/arm/ik.py
+++ b/rigify/rigs/biped/arm/ik.py
@@ -84,6 +84,8 @@ class Rig:
         else:
             self.layers = None
 
+        self.bend_hint = params.bend_hint
+
         self.primary_rotation_axis = params.primary_rotation_axis
 
     def generate(self):
@@ -198,6 +200,36 @@ class Rig:
             prop["soft_min"] = prop["min"] = 0.0
             prop["soft_max"] = prop["max"] = 1.0
 
+        # Bend direction hint
+        if self.bend_hint:
+            con = farm_p.constraints.new('LIMIT_ROTATION')
+            con.name = "bend_hint"
+            con.owner_space = 'LOCAL'
+            if self.primary_rotation_axis == 'X':
+                con.use_limit_x = True
+                con.min_x = pi / 10
+                con.max_x = pi / 10
+            elif self.primary_rotation_axis == '-X':
+                con.use_limit_x = True
+                con.min_x = -pi / 10
+                con.max_x = -pi / 10
+            elif self.primary_rotation_axis == 'Y':
+                con.use_limit_y = True
+                con.min_y = pi / 10
+                con.max_y = pi / 10
+            elif self.primary_rotation_axis == '-Y':
+                con.use_limit_y = True
+                con.min_y = -pi / 10
+                con.max_y = -pi / 10
+            elif self.primary_rotation_axis == 'Z':
+                con.use_limit_z = True
+                con.min_z = pi / 10
+                con.max_z = pi / 10
+            elif self.primary_rotation_axis == '-Z':
+                con.use_limit_z = True
+                con.min_z = -pi / 10
+                con.max_z = -pi / 10
+
         # IK Constraint
         con = farm_p.constraints.new('IK')
         con.name = "ik"
diff --git a/rigify/rigs/biped/leg/__init__.py b/rigify/rigs/biped/leg/__init__.py
index f2ea2e51..8f9286c7 100644
--- a/rigify/rigs/biped/leg/__init__.py
+++ b/rigify/rigs/biped/leg/__init__.py
@@ -98,6 +98,8 @@ class Rig:
         items = [('X', 'X', ''), ('Y', 'Y', ''), ('Z', 'Z', ''), ('-X', '-X', ''), ('-Y', '-Y', ''), ('-Z', '-Z', '')]
         group.primary_rotation_axis = bpy.props.EnumProperty(items=items, name="Primary Rotation Axis", default='X')
 
+        group.bend_hint = bpy.props.BoolProperty(name="Bend Hint", default=True, description="Give IK chain a hint about which way to bend.  Useful for perfectly straight chains.")
+
         group.separate_ik_layers = bpy.props.BoolProperty(name="Separate IK Control Layers:", default=False, description="Enable putting the ik controls on a separate layer from the fk controls.")
         group.ik_layers = bpy.props.BoolVectorProperty(size=32, description="Layers for the ik controls to be on.")
 
@@ -161,6 +163,9 @@ class Rig:
         r.label(text="Knee rotation axis:")
         r.prop(params, "primary_rotation_axis", text="")
 
+        r = layout.row()
+        r.prop(params, "bend_hint")
+
         col = layout.column()
         col.prop(params, "use_thigh_twist")
         col.prop(params, "use_shin_twist")
diff --git a/rigify/rigs/biped/leg/ik.py b/rigify/rigs/biped/leg/ik.py
index 265b4e32..54869b8e 100644
--- a/rigify/rigs/biped/leg/ik.py
+++ b/rigify/rigs/biped/leg/ik.py
@@ -134,6 +134,8 @@ class Rig:
         else:
             self.layers = None
 
+        self.bend_hint = params.bend_hint
+
         self.primary_rotation_axis = params.primary_rotation_axis
 
     def generate(self):
@@ -376,6 +378,36 @@ class Rig:
             prop["soft_min"] = prop["min"] = 0.0
             prop["soft_max"] = prop["max"] = 1.0
 
+        # Bend direction hint
+        if self.bend_hint:
+            con = shin_p.constraints.new('LIMIT_ROTATION')
+            con.name = "bend_hint"
+            con.owner_space = 'LOCAL'
+            if self.primary_rotation_axis == 'X':
+                con.use_limit_x = True
+                con.min_x = pi / 10
+                con.max_x = pi / 10
+            elif self.primary_rotation_axis == '-X':
+                con.use_limit_x = True
+                con.min_x = -pi / 10
+                con.max_x = -pi / 10
+            elif self.primary_rotation_axis == 'Y':
+                con.use_limit_y = True
+                con.min_y = pi / 10
+                con.max_y = pi / 10
+            elif self.primary_rotation_axis == '-Y':
+                con.use_limit_y = True
+                con.min_y = -pi / 10
+                con.max_y = -pi / 10
+            elif self.primary_rotation_axis == 'Z':
+                con.use_limit_z = True
+                con.min_z = pi / 10
+                con.max_z = pi / 10
+            elif self.primary_rotation_axis == '-Z':
+                con.use_limit_z = True
+                con.min_z = -pi / 10
+                con.max_z = -pi / 10
+
         # IK Constraint
         con = shin_p.constraints.new('IK')
         con.name = "ik"