OpenSAMP

A clean-room, open-source reimplementation of the SA-MP (San Andreas Multiplayer) client for GTA: San Andreas (US 1.0). Modern C++ with an ImGui overlay over D3D9.

OpenSAMP targets open.mp — the open-source, backward-compatible SAMP server. Because open.mp documents the wire protocol, the client is written from scratch and shares no code with the original SA-MP client.

Status: early alpha / work in progress. Connecting works, chat and dialogs work, and on-foot synchronization runs at 20 Hz. Vehicle synchronization is partial: the driver path is implemented but untested in game, and passenger / unoccupied / trailer sync are missing. No public builds are released at this time.

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What's in the box

• launcher/ — small launcher that starts gta_sa.exe and injects the native DLL into it.
• native/ — the DLL that lives inside the game process:
  • memory hooks and patches for GTA SA US 1.0 (via MinHook);
  • ImGui overlay on top of D3D9: chat, dialogs, debug windows;
  • networking layer on top of sampraknet (a RakNet fork used for SAMP wire-protocol compatibility);
  • connection state machine;
  • built-in crash dumper (minidump into the crash/ folder).

Requirements

• Windows 10/11, Visual Studio 2022 (toolset v143, x86).
• No submodules and nothing to fetch: imgui, sampraknet and MinHook are vendored under native/vendor/, with their provenance and licences recorded there.
• Target game: GTA: San Andreas, US 1.0 — other versions are not supported. You supply your own copy; nothing from Rockstar is distributed here.

Building and running

Full instructions are in docs/build.md. In short:

git clone <repo-url>
git config core.hooksPath tools/git-hooks

Put your GTA SA US 1.0 install in bin/ — that is both the game directory and the build output directory — then build opensamp.sln as Win32. The launcher lands at bin/opensamp.exe; run it, and it starts the game and injects bin/Client.Native.dll.

Connect in-game with //connect <ip> <port> [nick].

License

OpenSAMP is licensed under the GNU General Public License v3.0. See LICENSE for the full text. Because OpenSAMP is a clean-room reimplementation (not a SAMP fork), it is not bound by SAMP's license.

The copyleft is not merely a preference. The vendored RakNet fork (vendor/sampraknet) is available to us only under its GPL-v2-or-later option, so OpenSAMP cannot be relicensed permissively while it depends on that library. Vendored third-party code keeps its own upstream license; all of it is inventoried in THIRD-PARTY-NOTICES.md, including the gaps that still need closing.

Roadmap and open work

See TODO.md. It is a working document and it is candid about what is broken.

Contributing

See CONTRIBUTING.md and CODE_OF_CONDUCT.md.

Two rules matter more than the rest: no SA-MP client code may ever be pasted into this project — the clean-room provenance is the whole legal basis for it existing — and no GTA game asset may ever be committed. A pre-commit hook enforces the second one.