WarcraftXL client

The World of Warcraft 3.3.5a client, compiled from source, with a mod runtime built in

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Important

Building and running this client requires an original World of Warcraft 3.3.5a (build 12340) installation. No game data, no game binary and no part of either is in this repository; see NOTICE.md for what that means for the source itself.

🚀 Overview

A 64-bit WowClient64.exe that plays like the original and loads mods written against the WarcraftXL SDK. It is a fork of wowdecomp, the C++ decompilation of Wow.exe, with WarcraftXL core linked in: the same runtime that loads into the stock 32-bit client by detour is called here by the client's own source.

Key features

• Mods, without addresses. The runtime is told where the client is by calls the client makes, not by hooks into a shipped binary. A mod built for win-x64 from the SDK's template runs here unchanged; the same source built for win-x86 runs on the stock client.
• Seams, declared once. Every function the runtime attaches to is one row in core's seam table; this client calls that row's Before at the top of the function and After where it returns. What the seam means (the events it raises) is written once, in core, for both clients.
• Early. The runtime comes up from main, before the client reads its paths, its archives or its settings, so a mod's WXL_STAGE_EARLY runs before anything of the game.
• One build. cmake --build produces the executable and the WarcraftXL.dll it links, from the core checkout next door, into the same folder.

📋 Table of contents

• Overview
• Building
• Installing
• What it is
• Adding a seam
• Layout
• Troubleshooting
• Contributors
• License

⚡ Building

Prerequisites

• Visual Studio 2022 or newer with the Desktop development with C++ workload. Visual Studio 2026 (MSVC 14.51) builds it as is; the upstream README's request for 2022 is a minimum, not a requirement.

• CMake 3.21 or newer (the one that ships with Visual Studio works).

• Checkouts of WarcraftXL/core and WarcraftXL/sdk beside this one:

  WarcraftXL/
      client/     this repository
      core/       the runtime, built by this tree as win-x64
      sdk/        the contract, headers only
  

  Anywhere else: pass -DWXL_CORE_DIR=<path> and -DWXL_SDK_DIR=<path> at configure time.

x64

cmake -S . -B build/x64 -G "Visual Studio 18 2026" -A x64
cmake --build build/x64 --config Release --target WowClient --parallel

The client and its runtime are written to bin/Win/:

File	What it is
WowClient64.exe	the client, with the crash logger (WOWCLIENT_CRASH_LOG, on by default)
Wow64.exe	the client without it (--target Wow)
WarcraftXL.dll	the runtime, built from ../core as win-x64
XvidDecoder.dll	the cinematic decoder
Mods/wxl.lua/	the runtime of the Lua mods, built from ../sdk/lua: a Lua mod needs nothing else

The first configure downloads LuaJIT, which wxl.lua embeds, at a fixed commit; core's README says how to give it one already built instead.

The decompiled sources carry around a thousand warning sites of their own (narrowing conversions, enumerator values, unreferenced parameters); the fork does not try to silence them. The code under WarcraftXL/ is held to /W4 /permissive- and compiles clean.

Win32

The Win32 configuration exists so that struct layouts can be measured against the original binary (core/tools/layouts/). It compiles but does not link at this fork point: the Win64 sources BotCheck.cpp, Battlenet.cpp, BattlenetLogin.cpp and PatchDownloadGlue.cpp have no Win32 counterpart, which leaves 8 unresolved symbols. The upstream README's claim that Win32 still builds is stale. Configuring it also needs NASM (-DNASM_EXECUTABLE=<path>). No runtime is linked on Win32; the seam calls compile to nothing there.

📦 Installing

1. Copy the Data folder of your 3.3.5a client into bin/Win/, so that bin/Win/Data/ holds the .MPQ archives, or copy WowClient64.exe, WarcraftXL.dll, XvidDecoder.dll and the Mods/wxl.lua/ folder into a folder that already has one.
2. Point Data/<locale>/realmlist.wtf at the server you want to connect to.
3. Copy the mods you want into Mods/ next to the executable, each as its own folder with a mod.json and bin/x64/<name>.dll. The SDK's template builds exactly that shape. A Lua mod is a folder with its init.lua, run by Mods/wxl.lua/.
4. Start WowClient64.exe. The runtime's log is Logs/WarcraftXL.log next to it; the client's own logs are in the same folder.

The signature checks of the original are kept (WOWDECOMP_DISABLE_SIGNATURE_CHECKS=OFF): modified interface files need the option, or a mod such as core's wxl.glue-unlock on the stock client.

🔎 What it is

The client calls the runtime at three places, and nowhere else:

Where	What
WoW/Source/Win64/WinMain.cpp, main	WarcraftXL::Init(): hands the runtime the client's accessors and calls WarcraftXLInit, before CommonMain
WoW/Source/WorldClient/World.cpp, World::Preload	wxl::seam::World::Preload::Before as the function starts, ::After as it returns
CMakeLists.txt	add_subdirectory(WarcraftXL)

Everything behind those lines is under WarcraftXL/: the glue that builds core, links it and copies the DLL next to the executable, the accessor table (wxl_core_init from core's include/wxl/core/init.h, today the map id through World::QueryMapId), and the adapters the seam calls use (WarcraftXL::Vec3, a C3Vector as the wxl_vec3 the boundary carries).

What a mod gets on this client, by the runtime's own account:

	here (x64)	stock client (x86)
events	WorldEnter, WorldLeave	the same
wxl.hook by name	not published: a seam is two calls inside a function the client compiled, not a function a detour can replace	the seams and the extra points, detourable
wxl.hook.raw, wxl.patch	never: no fixed address and nothing to patch in a program we compile	yes

World::Preload is called with the loading screen for a login and a teleport, and without it for the preloads around a cinematic camera, a far-sight target or a game object. Only the first kind is a world change, and only that kind raises the events.

🧵 Adding a seam

A seam is a client function the runtime attaches to. Adding one touches core first, then one function here:

1. In core, add a row to the domain's table under include/wxl/seams/ (or a new table, included from seams.def): the domain, the function's name, its qualified name as this tree spells it, and its parameters as the C boundary sees them. Write the body in src/seams/<Domain>.cpp: what Before and After read, decide and raise. Core's x86 build attaches a detour at the function's address from that row alone.
2. Here, include WarcraftXL/Seams.h in the function's file and call wxl::seam::<Domain>::<Name>::Before(...) as the function starts and ::After(...) where it returns, with the same arguments. Those are the only lines the function gains.

The name is the function's, never the event's: World.Preload, not World.Enter. Where and what are two different columns.

📂 Layout

WarcraftXL/              the integration: CMake, Init.h/.cpp (WarcraftXLInit), Seams.h (adapters)
WoW/                     the game: objects, world, interface, networking, database, glue screens
Engine/                  the engine: storage, graphics, sound, scripting, frames
Tools/                   WowClient (the executable with the crash logger), the Xvid decoder
ThirdParty/              vendored libraries, each under its own license
README.upstream.md       wowdecomp's own README, as forked
UPSTREAM.md              the fork point and how upstream is tracked
NOTICE.md                provenance and what is, and is not, licensed

🔧 Troubleshooting

Symptom	Cause
CMake: WXL_CORE_DIR (...) is not a WarcraftXL checkout	core or the SDK is not beside this repository: clone them there, or pass -DWXL_CORE_DIR / -DWXL_SDK_DIR
The client does not start, 0xc000007b or 0xc0000142	WarcraftXL.dll next to the executable is not the 64-bit build, or is missing
No Logs/WarcraftXL.log	the runtime never came up: the executable was started from a folder without write access, or is not this build
A mod is missing from the log	wrong folder shape; it needs Mods/<id>/mod.json and Mods/<id>/bin/x64/<name>.dll
refused … requires service wxl.hook.raw or wxl.patch	the mod is written for the stock client's addresses; it has nothing to attach to here
refused … requires service wxl.hook	the mod wants to detour a named point; here they are seams, so subscribe to the events they raise instead
Win32: 8 unresolved externals	expected at this fork point, see Win32

🤝 Contributors

Upstream's contributors are credited in UPSTREAM.md. Tyrallis brought the model and appearance seams, skins over 65535 indices, the optional geometry's geoset ids and textures over 4 MB (pull request #1).

📄 License

This tree is a decompilation and carries no license; NOTICE.md says why and what that implies. The runtime it links is WarcraftXL core, MIT; the contract mods are written against is WarcraftXL sdk, MIT.

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