bone_deletion_script.txt

'''
Adapted from https://blender.stackexchange.com/a/226914/132453
Script written by: https://github.com/ssbucarlos

Use this Blender script to simplify bone structure for complicated models
Required in order to import complicated models like MMD into Genshin

'''
import bpy

def transfer_weights(source, target, obj):
    source_group = obj.vertex_groups.get(source.name)
    if source_group is None:
        return
    source_i = source_group.index
    target_group = obj.vertex_groups.get(target.name)
    if target_group is None:
        target_group = obj.vertex_groups.new(name=target.name)
        
    for v in obj.data.vertices:
        for g in v.groups:
            if g.group == source_i:
                target_group.add((v.index,), g.weight, 'ADD')
    obj.vertex_groups.remove(source_group)
    

def remove_bone(source, target):
    for o in bpy.data.objects:
        transfer_weights(source, target, o)
    edit_bone = bpy.context.object.data.edit_bones.get(source.name)
    bpy.context.object.data.edit_bones.remove(edit_bone)


def find_parent_not_in_collection(bone, collection):
    if bone.parent in collection:
        return find_parent_not_in_collection(bone.parent, collection)
    else:
        return bone.parent

def main():
    selected_bones = [bone for bone in bpy.context.object.data.edit_bones if bone.select is True]
    for selected_bone in selected_bones:
        target = find_parent_not_in_collection(selected_bone, selected_bones)
        remove_bone(selected_bone, target)
        
main()