🧩 reeutils, IntelOrca.Biohazard.REE

A .NET library for working with RE Engine resource formats and PAK files. Primarily developed to support the biorand project, but useful for modding most RE engine games.

🚀 Usage

Add the package to your project by referencing the NuGet package in your .csproj:

<PackageReference Include="IntelOrca.Biohazard.REE" Version="1.4.2" />

Basic example showing how to open a file from the game's patched pak files, modify it and write a new patch pak:

using IntelOrca.Biohazard.REE.Package;
using IntelOrca.Biohazard.REE.Rsz;

var repo = RszRepositorySerializer.Default.FromJsonFile(@"C:\reasy\rszre4.json");
using var pak = new RePakCollection(@"C:\Program Files (x86)\Steam\steamapps\common\RESIDENT EVIL 4  BIOHAZARD RE4");

// Get user data and create new modified version
const string guiParamPath = "natives/stm/_chainsaw/appsystem/ui/userdata/guiparamholdersettinguserdata.user.2";
var userFileBuilder = new UserFile(pak.GetEntryData(guiParamPath)).ToBuilder(repo);
var root = userFileBuilder.Objects[0];
root = root.Set("_InGameShopGuiParamHolder._HoldTime_Purchase", 0.1f);
userFileBuilder.Objects = [root];
var newUserFile = userFileBuilder.Build();

// Create new patch pak file with modified user file
var pakBuilder = new PakFileBuilder();
pakBuilder.AddEntry(guiParamPath, newUserFile.Data);
pakBuilder.Save("re_chunk_000.pak.patch_006.pak");

📦 Build

• Requirements: .NET SDK 10.0.
• Build the solution:

dotnet build reeutils.sln

🧪 Tests

• Run tests with the dotnet test runner:

dotnet test

• Note: many tests require access to original game PAK files and RSZ type JSON dumps. You must configure local paths to where Resident Evil games are installed before running those tests.

  • By default the test helper test/IntelOrca.Biohazard.REE.Tests/OriginalPakHelper.cs contains example paths used on the author machine. Edit that file to point to your game installation directories or ensure equivalent paths exist on your machine.
  • The RSZ type JSON files used by tests are referenced from a local reasy clone in the tests (see GetTypeRepository in OriginalPakHelper.cs). Place or point those JSON dumps to the expected paths or update the test helper accordingly.

⚙️ Design

• The library is designed around immutability and builder patterns for thread-safety and efficient cloning. Builders provide explicit, safe mutation paths while core types remain immutable to allow safe sharing across threads and cheap copy-on-write style operations.

🙏 Credits

• Thanks to the REasy project for RSZ JSON dumps and type information used in tests and tooling.
• Historical tooling and ideas inspired by RSZTool.
• Additional contributions and community tooling from Namsku.

🧾 License

This repository is MIT licensed.