Regenerate Unity asset GUIDs while preserving local asset references. Useful for duplicating an entire directory of inter-dependent assets.

RemapAssetRefs.py

import os
import sys
import argparse
import uuid
import logging
from concurrent.futures import ThreadPoolExecutor
from typing import List, Tuple, Dict, Optional

logging.basicConfig(level=logging.INFO, format='%(message)s')

def parse_arguments() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description='Remap asset references in a directory.')
    parser.add_argument('--dry-run', action='store_true', help='Perform a dry run without making changes.')
    parser.add_argument('directory', type=str, help='The directory to process.')
    return parser.parse_args()

def validate_directory(directory: str) -> None:
    if not os.path.isdir(directory):
        logging.error(f"Directory {directory} does not exist.")
        sys.exit(1)

def find_files(directory: str, extensions: List[str]) -> List[str]:
    return [os.path.join(root, file)
            for root, _, files in os.walk(directory)
            for file in files if any(file.endswith(ext) for ext in extensions)]

def create_replacement_guid_for_meta_file(file_path: str) -> Optional[Tuple[str, str]]:
    with open(file_path, 'r', encoding='utf-8', errors='ignore') as f:
        for line in f:
            if line.startswith('guid: '):
                guid = line.split(' ')[1].strip()
                new_guid = uuid.uuid4().hex
                return guid, new_guid
    return None

def replace_guid_in_file(file_path: str, guid_map: Dict[str, str], dry_run: bool) -> None:
    with open(file_path, 'r', encoding='utf-8', errors='ignore') as f:
        content = f.read()

    original_content = content
    for old_guid, new_guid in guid_map.items():
        content = content.replace(old_guid, new_guid)

    if content != original_content:
        logging.info(f"Updated GUIDs in {file_path}")
        if not dry_run:
            with open(file_path, 'w', encoding='utf-8', errors='ignore') as f:
                f.write(content)

def process_meta_files(meta_files: List[str], dry_run: bool) -> Dict[str, str]:
    guid_map = {}
    for meta_file in meta_files:
        result = create_replacement_guid_for_meta_file(meta_file)
        if result:
            old_guid, new_guid = result
            guid_map[old_guid] = new_guid
    
    with ThreadPoolExecutor() as executor:
        futures = [executor.submit(replace_guid_in_file, meta_file, guid_map, dry_run) for meta_file in meta_files]
        for future in futures:
            future.result()

    return guid_map

def main() -> None:
    args = parse_arguments()
    validate_directory(args.directory)

    meta_files = find_files(args.directory, ['.meta'])
    asset_files = find_files(args.directory, ['.prefab', '.mat', '.asset', '.unity'])

    guid_map = process_meta_files(meta_files, args.dry_run)

    with ThreadPoolExecutor() as executor:
        futures = [executor.submit(replace_guid_in_file, file_path, guid_map, args.dry_run) for file_path in asset_files]
        for future in futures:
            future.result()

if __name__ == "__main__":
    main()