assets/characters/infantry/post_rig.py

import bpy
from bpy.types import Constraint, PoseBone

rig = bpy.data.objects["skeleton_insurrectionist"]

## FIX PARENTS
def reparent(b: str, newParent: str = 'DEF-spine'):
    rig.data.edit_bones[b].parent = rig.data.edit_bones[newParent]
def fix(b: str):
    p = rig.data.edit_bones[b].parent.name.replace('ORG','DEF')
    reparent(b, p)

# Switch to EDIT mode to modify bone hiearchy to be proper for Unreal
bpy.ops.object.mode_set(mode='EDIT')

# List of bones that need to be reparented to their deforming counterparts
fixList = [
    # Hands
    'DEF-thumb01.L',
    'DEF-index01.L',
    'DEF-middle01.L',
    'DEF-ring01.L',
    'DEF-pinky01.L',
    
    # Arms
    'shoulder.L',
    'breast.L',
    
    # Legs
    'DEF-thigh.L',
]
# Iterate through and fix each bone
for item in fixList:
    fix(item)
    if item.endswith('.L'): # If it's left-sided, fix right-side counterparts too
        fix(item.replace('.L','.R'))

# Pelvis parents work a little differently
reparent('DEF-pelvis.L', 'DEF-spine')
reparent('DEF-pelvis.R', 'DEF-spine')
# Deform parents on palms are actually parented to originals, so skip that layer
reparent('DEF-palm.01.L', 'DEF-hand.L')
reparent('DEF-palm.02.L', 'DEF-hand.L')
reparent('DEF-palm.03.L', 'DEF-hand.L')
reparent('DEF-palm.04.L', 'DEF-hand.L')
reparent('DEF-palm.01.R', 'DEF-hand.R')
reparent('DEF-palm.02.R', 'DEF-hand.R')
reparent('DEF-palm.03.R', 'DEF-hand.R')
reparent('DEF-palm.04.R', 'DEF-hand.R')

# Force axe to be exported by setting it as a deform bone
rig.data.edit_bones['axe'].use_deform = True

# Switch into POSE mode to set up animation constraints
bpy.ops.object.mode_set(mode='POSE')

## Declare Functions for animation constraints
def arrcopy(copyTo, copyFrom):
    for i in range(min(len(copyTo), len(copyFrom))):
        copyTo[i] = copyFrom[i]
def drv_blend_1D(shape_target: str, key_target: str, bone_name: str, max_x: float, prop: str = 'LOC_Y', formula: str = ''):
    block = bpy.data.shape_keys[shape_target].key_blocks[key_target]
    bmin = block.slider_min
    bmax = block.slider_max
    
    block.driver_remove('value')
    fcurve = block.driver_add('value')
    d = fcurve.driver
    d.type = 'SCRIPTED'
    
    if formula == '':
        d.expression = str(bmax / max_x) + '*x'
    else:
        d.expression = formula
    
    v = d.variables.new()
    v.name = 'x'
    v.type = 'TRANSFORMS'
    t = v.targets[0]
    t.id = rig
    t.bone_target = bone_name
    t.transform_type = prop
    t.transform_space = 'LOCAL_SPACE'
def drv_constraint_1D(c: Constraint, bone_name: str, max_x: float, prop: str = 'LOC_Y', formula: str = ''):
    bmin = 0.0
    bmax = 1.0
    
    c.driver_remove('influence')
    fcurve = c.driver_add('influence')
    d = fcurve.driver
    d.type = 'SCRIPTED'
    
    if formula == '':
        d.expression = str(bmax / max_x) + '*x'
    else:
        d.expression = formula
    
    v = d.variables.new()
    v.name = 'x'
    v.type = 'TRANSFORMS'
    t = v.targets[0]
    t.id = rig
    t.bone_target = bone_name
    t.transform_type = prop
    t.transform_space = 'LOCAL_SPACE'
def constrain_slider(b: PoseBone, minimum: float = 0, maximum: float = 0.06):
    c = b.constraints.new('LIMIT_LOCATION')
    c.use_min_y = True
    c.use_max_y = True
    c.min_y = minimum
    c.max_y = maximum
    c.use_transform_limit = True
    c.owner_space = 'LOCAL'

# Fix widget scalings
for b in rig.pose.bones:
    if b.name.startswith("menu_"):
        b.use_custom_shape_bone_size = False
        b.custom_shape_translation = (0.0, 0.03, 0.0)
        b.custom_shape_scale_xyz = (0.06, 0.06, 0.0)
        arrcopy(b.lock_scale, [False, True, False])
    elif b.name.startswith("slider1d"):
        b.use_custom_shape_bone_size = False
        b.custom_shape_scale_xyz = (0.02, 0.003, 0.005)
        
        arrcopy(b.lock_location, [True, False, True])
        arrcopy(b.lock_rotation, [True, True, True])
        arrcopy(b.lock_scale, [True, True, True])
        b.lock_rotation_w = True
    elif b.name == "axe_gripadjust":
        b.custom_shape_scale_xyz = (1.0, 0.8, 0.1)

# Constrain menu sliders so they are limited to proper bounds
constrain_slider(rig.pose.bones.get('slider1d_axe_gripadjust'))
constrain_slider(rig.pose.bones.get('slider1d_axe_lefthand_grip'))
constrain_slider(rig.pose.bones.get('slider1d_axe_smear'), -0.03, 0.03)

# Arm and Hand switch for Axe Base
# https://blender.stackexchange.com/questions/46928/set-bone-constraints-via-python-api#46986
axe_base = rig.pose.bones.get("axe_base")
axe_constraint: Constraint = None
if axe_base is not None:
    axe_constraint = axe_base.constraints.new('COPY_TRANSFORMS')
    axe_constraint.target = rig
    axe_constraint.subtarget = 'DEF-hand.R' # note subtarget uses name not object
    axe_constraint.target_space = 'POSE'
    axe_constraint.owner_space = 'POSE'
    axe_constraint.influence = 0.0

# Left-Hand grip switch for Axe
left_hand = rig.pose.bones.get("hand_ik.L")
lh_constraint: Constraint = None
if axe_base is not None:
    lh_constraint = left_hand.constraints.new('COPY_TRANSFORMS')
    lh_constraint.target = rig
    lh_constraint.subtarget = 'axe_grip_lefthand' # note subtarget uses name not object
    lh_constraint.target_space = 'POSE'
    lh_constraint.owner_space = 'POSE'
    lh_constraint.influence = 0.0

## Set up driver constraint for the switches
drv_constraint_1D(axe_constraint, 'slider1d_axe_gripadjust', 0.06)
drv_constraint_1D(lh_constraint, 'slider1d_axe_lefthand_grip', 0.06)

## Set up smear effect drivers for axe
drv_blend_1D('Key', 'smear_down', 'slider1d_axe_smear', 0.03)
drv_blend_1D('Key', 'smear_up', 'slider1d_axe_smear', -0.03)