Unfold

WIP modding tool for the Defold game engine.

Current Features

• Export assets

Planned Features

• Import assets
• Decompile/recompile assets
  • Both features above require a native extension version of lua-lz4, specifically the block_compress() and block_decompress() functions
• Mod loading

Installation

Grab a pre-built version from the releases section or download the project and build it using Defold.

Archive Format

Below is everything I know about Defold's archive format, for those who want to contribute or are just curious.

game.arcd

Contains the actual data of the game files and not much else.

game.arci

The archive index. It's a binary file with a header, a list of hashes of each file, and a list of data about each file.

Header Format

Offset	Size	Description
0x0	0x4	Index version. It's 4 at the time of writing
0x4	0x4	Padding
0x8	0x8	"UserData, used in runtime to distinguish between if the index and resources are memory mapped or loaded from disk", according to the source code. Not sure what this means
0x10	0x4	The number of entries in the index
0x14	0x4	Starting offset of the entry list
0x16	0x4	Starting offset of the hash list
0x1a	0x4	The length of each hash
0x1e	0x10*	The MD5 hash of the index file. Its length is determined by MD5_HASH_DIGEST_BYTE_LENGTH (0x10 at the time of writing)

Hash Format

These are hashes whose lengths are defined in the index header. Each hash is stored in a block of size HASH_MAX_LENGTH, the rest of the space gets filled in with zeros. The hash algorithm used is defined by the manifest header. Hashes seem to only be used as an identifier, not to check that the files are valid.

Entry Format

Offset	Size	Description
0x0	0x4	Offset of the file data in game.arcd
0x4	0x4	Uncompressed size of the file
0x8	0x4	Compressed size of the file (0xFFFFFFFF if not compressed)
0xc	0x4	Archive entry flags (see below)

Archive Entry Flags

00000000 00000000 00000000 00000000
                                ||| Encrypted
                                || Compressed
                                | Live update

game.dmanifest

This is simply a compiled Google protobuf file. The definition file is easy to read, so go check it out here.

Asset Format

Assets are protobufs that have been compressed in LZ4 block format. The definition files are scattered throughout the Defold repo, but they all use the naming format *_ddf.proto, making them easily searchable. The files included in the archive aren't always the same as the ones in the source project. For instance, textures are converted from atlases and image files to .texturec and .texturesetc file.