<img src="assets/HydraHook_128x128.png" align="left" /> HydraHook

API-Hooking and rendering framework for DirectX-based games.

About

HydraHook consists of a self-contained library (DLL) which exposes a minimalistic API for rendering custom content in foreign processes eliminating the need for in-depth knowledge about Direct3D and API-hooking. The most common use-case might be drawing custom overlays on top of your games. The framework takes care about pesky tasks like detecting the DirectX version the game was built for.

[!CAUTION] Use caution when injecting HydraHook into any game protected by anti-cheat software. API hooking and DLL injection are commonly detected by anti-cheat systems and may result in permanent bans from online services. Use only with games you own and in environments where such use is permitted.

[!NOTE] The authors of this project do not condone the use of HydraHook in cheating software. The project's motivation has been curiosity and education entirely.

Features

• Runtime injection and ejection — No launcher required. Inject into any running DirectX process and eject via FreeLibrary when done. Supports mid-process injection (e.g. D3D12 games already running). Graceful shutdown via ExitProcess / PostQuitMessage / FreeLibrary hooks avoids loader-lock and unload races.

• Performance-focused — Lock-free hot path for hook callbacks (atomic counters only; no mutex, no kernel transition). Shutdown uses loader-lock-safe remove_nothrow to avoid deadlocks during process exit.

• No external dependencies at runtime — Everything needed is statically linked in. Just drop the DLL into the target process; no redistributables or runtime packages required.

Supported DirectX versions

• DirectX 9.0
• DirectX 9.0 Extended (Vista+)
• DirectX 10
• DirectX 11
• DirectX 12

How to build

Prerequisites

• Visual Studio 2022 (Community Edition is free)
• Windows SDK

Build steps

1. Clone the repository and initialize submodules: git submodule update --init --recursive
2. Open HydraHook.sln in Visual Studio and build

Dependencies (spdlog, detours, imgui, directxtk) are declared in vcpkg.json and installed via vcpkg (included as a submodule). Run prepare-deps.bat from a Developer Command Prompt for VS 2022 (or x64 Native Tools Command Prompt) before the first build in Visual Studio; the build will use existing vcpkg_installed if present.

Pre-built binaries

[!WARNING] The downloads contain a DLL Injector utility which might be flagged as unsafe by the browser due to it sharing behavior with malicious code. Use at your own risk!

Pre-built binaries are available from the buildbot. Note: these builds may be outdated; for the latest code, build from source.

How to use

Inject the resulting host library (e.g. HydraHook-ImGui.dll) into the target process first using a DLL injection utility of your choice (you can ofc. use mine as well). The following example loads the imgui sample:

.\Injector -n hl2.exe -i HydraHook-ImGui.dll

Just make sure your host library doesn't require any external dependencies not present in the process context or you'll get a LoadLibrary failed error.

Diagnostics

The core library logs its progress and potential errors to HydraHook.log. It tries to write in this order: (1) the directory of the process executable, (2) the directory of the HydraHook DLL, (3) %TEMP% if both prior locations fail (e.g. no write permissions).

Demos

The following demo videos show imgui being rendered in foreign processes using different versions of DirectX. Click a thumbnail to watch the video.

DirectX 9

Half-Life 2, 32-Bit

DirectX 9 Ex

Castlevania: Lords of Shadow, 32-Bit

DirectX 10

Bioshock 2, 32-Bit

DirectX 11

Road Redemption, 64-Bit

DirectX 12

Supported on 64-bit builds. The ImGui sample automatically detects and hooks DX12 games.

BEHEMOTH, 64-Bit

Sources

Dependencies

This project uses the following libraries (via vcpkg):

Core library only:

• spdlog – Fast C++ logging library
• Microsoft Detours – API hooking library

Sample projects only:

• Dear ImGui – Immediate mode GUI
• DirectXTK – DirectX Toolkit
• OpenCV – Computer vision library

References & inspiration

• DX9-Overlay-API
• Creating a render target in DirectX 11
• ion RE Library
• C# – Screen capture and overlays for Direct3D 9, 10 and 11 using API hooks
• HelloD3D12