assets/characters/infantry/post_rig.py

import bpy
from bpy.types import Constraint, PoseBone

rig = bpy.data.objects["skeleton_infantry"]
BGRP_SPECIAL = 2
BGRP_TWEAK = 3
BGRP_EXTRA = 4

## 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 drv_toggle_1D(a: PoseBone, b: PoseBone, slider: PoseBone):
    pass
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'
def cpy_transforms(b: PoseBone, subtarget, influence = 1.0):
    constraint = b.constraints.new('COPY_TRANSFORMS')
    constraint.target = rig
    constraint.subtarget = subtarget # note subtarget uses name not object
    constraint.target_space = 'POSE'
    constraint.owner_space = 'POSE'
    constraint.influence = influence
    return constraint

## Fix widget scalings, and constrain them
for b in rig.pose.bones:
    ## MENUS / WIDGETS
    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])
        b.bone_group_index = BGRP_EXTRA
    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
        b.bone_group_index = BGRP_SPECIAL
    
    ## WEAPONS
    elif b.name.endswith("_slide"):
        b.bone_group_index = BGRP_TWEAK
        b.custom_shape_scale_xyz = (2.0, 2.0, 2.0)
        arrcopy(b.lock_location, [True, False, True])
        arrcopy(b.lock_scale, [True, True, True])
        arrcopy(b.lock_rotation, [False, False, True])
        
    ### BATON
    elif b.name.startswith("grip_baton"):
        b.custom_shape_scale_xyz = (0.2, 2.6, 0.2)
        b.custom_shape_translation = (0.0, 0.25, 0.0)
        if b.name.endswith("_constrained"):
            b.custom_shape_scale_xyz *= 0.9
            b.bone_group_index = BGRP_EXTRA
    elif b.name == "baton_handR_grip":
        b.custom_shape_scale_xyz = (0.2, 1.0, 0.8)
    
    ### GUN
    elif b.name.startswith("grip_gun"):
        b.custom_shape_scale_xyz = (0.1, 1.5, 0.2)
        b.custom_shape_translation = (0.0, 0.185, 0.0)
    elif b.name == "gun_ammunition":
        b.custom_shape_scale_xyz = (0.4, 1.0, 0.4)
        b.custom_shape_translation = (0.0, 0.06, 0.0)
    elif b.name == "gun_trigger":
        b.custom_shape_scale_xyz = (0.3, 1.0, 0.7)
        b.custom_shape_translation = (0.0, 0.015, 0.0)
        arrcopy(b.lock_rotation, [False, True, True])
        arrcopy(b.lock_location, [True, True, True])
        arrcopy(b.lock_scale, [True, True, True])
    elif b.name == "gun_muzzle":
        b.custom_shape_scale_xyz = (0.1, 1.1, 0.2)
        b.custom_shape_translation = (0.0, 0.14, 0.0)
        arrcopy(b.lock_location, [True, False, True])
        arrcopy(b.lock_rotation, [True, True, True])
        arrcopy(b.lock_scale, [True, False, True])
        b.lock_rotation_w = True
    
    elif b.name == "jetpack_grip":
        b.custom_shape_scale_xyz = (1.25, 2.5, 0.8)

    ## BODY
    elif b.name == "neck.001":
        arrcopy(b.lock_location, [True, True, True])


# Constrain slider widgets
constrain_slider(rig.pose.bones.get('slider1d_baton_constrain'), 0.0, 0.06)
constrain_slider(rig.pose.bones.get('slider1d_baton_handIK'), 0.0, 0.06)
constrain_slider(rig.pose.bones.get('slider1d_gun_handRIK'), 0.0, 0.06)
constrain_slider(rig.pose.bones.get('slider1d_gun_handLIK'), 0.0, 0.06)

## Switch Baton Grip's bound parent, default parent to arm, but can switch to separate control
baton_grip = rig.pose.bones.get("grip_baton")
cpy_transforms(baton_grip, 'grip_baton_constrained', 1.0) # Default to hand grip
bg_constraint = cpy_transforms(baton_grip, 'grip_baton_free', 0.0)
drv_constraint_1D(bg_constraint, 'slider1d_baton_constrain', 0.06)

## Align right hand to baton grip
rightHand = rig.pose.bones.get("MCH-upper_arm_ik_target.R")
bh_constraint = cpy_transforms(rightHand, 'baton_handR_grip', 0.0) # Default to hand grip
drv_constraint_1D(bh_constraint, 'slider1d_baton_handIK', 0.06)

# Gun
gun_grip = rig.pose.bones.get("grip_gun")
cpy_transforms(gun_grip, 'grip_gun_free', 1.0) # Inherit transforms, but be tree-agnostic for IK

## Align hands to gun grip
ghr_constraint = cpy_transforms(rightHand, 'gun_handR_grip', 0.0)
drv_constraint_1D(ghr_constraint, 'slider1d_gun_handRIK', 0.06)

leftHand = rig.pose.bones.get("MCH-upper_arm_ik_target.L")
ghl_constraint = cpy_transforms(leftHand, 'gun_handL_grip', 0.0)
drv_constraint_1D(ghl_constraint, 'slider1d_gun_handLIK', 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)


# Enforce deformation bones for FBX export
def mfx(boneName: str): # Mark for export
    rig.data.bones[boneName].use_deform = True

EXPORT_LIST = [
'DEF-spine.005', # Helmet
'camera_head',
'camera_base',
'grip_baton', # Baton
'jetpack_grip', # Jetpack
'grip_gun', # Gun
'gun_ammunition',
'gun_trigger',
'gun_muzzle',
]

if True:
    for b in EXPORT_LIST:
        mfx(b)