124 lines
7.6 KiB
Markdown
124 lines
7.6 KiB
Markdown
# Integration Project
|
|
|
|
Unreal Engine 5.5.4 game project running on Linux (PopOS). This is **Luprex**, a game engine built on top of Unreal that uses Lua as its scripting language. The engine handles multiplayer networking automatically so scripters don't write networking code.
|
|
|
|
## Build System
|
|
|
|
- Use `build.py` for all builds. Do NOT follow Epic's standard build instructions.
|
|
- `build.py all` — full rebuild (engine, game, intellisense, project files)
|
|
- `build.py c++` — lightweight rebuild (only if you've only edited C++ files in this repo)
|
|
- Lua and Blueprint edits don't require a rebuild.
|
|
- Do not edit `Integration.uproject` directly — edit `Integration.uproject.tpl.json` instead, then run `build.py`.
|
|
- Do not run builds yourself. The IDE builds automatically when the user runs the code.
|
|
|
|
## Project Structure
|
|
|
|
- `Source/Integration/` — Game module C++ source (Unreal-side driver code)
|
|
- `Content/` — Unreal assets
|
|
- `luprex/` — The Luprex DLL (driven portion of the engine)
|
|
- `Docs/` — Documentation. When trying to understand this system, start with the markdown files in the Docs directory.
|
|
- `Config/` — Unreal config files
|
|
- `EnginePatches/` — Custom engine modifications
|
|
|
|
## Architecture: Driver / Driven Separation
|
|
|
|
The engine is split into two halves:
|
|
|
|
- **Driven portion (Luprex DLL)** — All game logic. Deterministic, OS-independent, no I/O. Pure standard-compliant C++. Organized as a library with class `DrivenEngine` as the top-level API.
|
|
- **Driver (EXE or Unreal integration)** — Handles all I/O (sockets, files). Feeds events into the driven portion via `struct EngineWrapper`, a pure C interface of function pointers. There's a command-line driver and an Unreal driver.
|
|
|
|
The driven portion never calls into the driver. Output goes through polled buffers. This separation enables deterministic replay for debugging: the driver logs all events, and can replay them to reproduce crashes.
|
|
|
|
## Architecture: World Models and Predictive Reexecution
|
|
|
|
There are four types of world models, each a separate `World` instance with its own Lua interpreter:
|
|
|
|
- **Master** (server, one) — authoritative state, executes commands immediately when they arrive.
|
|
- **Server-synchronous** (server, one per client) — executes commands when the acknowledgement is issued.
|
|
- **Client-synchronous** (client, one) — executes commands when the same acknowledgement arrives; determinism keeps it in perfect sync with its server-synchronous counterpart.
|
|
- **Asynchronous** (client, one) — snapshot of client-synchronous with predictions applied for responsive rendering; rolled back when server confirms.
|
|
|
|
The synchronous models lag behind the master but stay in lockstep with each other. The asynchronous model fills the latency gap for the player.
|
|
|
|
Two update channels flow into the synchronous models:
|
|
1. **Command acknowledgements** — for the client's own actions, keeping the two synchronous models in lockstep.
|
|
2. **Difference transmission** — for everything else (other players' actions, server-side events, tangibles entering/leaving visibility).
|
|
|
|
See `Docs/Predictive-Reexecution.md` for the full explanation.
|
|
|
|
## Architecture: Lua / Unreal Separation
|
|
|
|
Lua scripts have no access to the Unreal API whatsoever. The scripter works with plain Lua tables, animation queues of key-value tuples, and coroutines. There are no "unreal bindings." The Luprex DLL is engine-agnostic — Unreal (or any other front end) interprets the animation queues and renders accordingly.
|
|
|
|
Small concessions to reality exist in animation step tuples:
|
|
- `bp` — names which Tangible Actor blueprint to use for rendering
|
|
- `mat_color` — a persistent value that hints at material color
|
|
These are still just key-value data; the script never touches the Unreal API directly.
|
|
|
|
## Architecture: Tangibles
|
|
|
|
Tangibles are game objects. Each has:
|
|
- A **Lua table** — the scripter stores arbitrary game data here.
|
|
- An **animation queue** — a fixed-length sequence of key-value animation steps.
|
|
- A **C++ tangible** — holds the ID, animation queue, positional tracker, etc.
|
|
- A **metatable** — engine-reserved; contains __id, __index (class), __threads.
|
|
|
|
Animation steps contain **transient** values (like `action`) that don't propagate, and **persistent** values (like `xyz`, `facing`, `plane`) that carry forward automatically.
|
|
|
|
On the Unreal side, **Tangible Actor blueprints** (TangibleStaticMesh, TangibleSkeletalMesh, TangibleCharacter) monitor the animation queue and perform the visual animations. Custom blueprints can interpret the queue in any way they want.
|
|
|
|
## Architecture: Lua Environment
|
|
|
|
- **Patched Lua runtime** — deterministic table iteration, deterministic table length, flag bits on tables, generalized less-than, C++ exceptions instead of longjmp, and more. See `Docs/A-Summary-of-our-Lua-Patches.md`.
|
|
- **LuaStack API** — custom C++ API replacing the standard Lua C API. Uses `LuaDefStack`/`LuaExtStack` with `LuaArg`/`LuaVar`/`LuaRet` slots mapped to stack positions. See `Docs/Our-In-House-Lua-API.md`.
|
|
- **LuaDefine macro** — declares Lua-callable C++ functions and auto-registers them in a global registry for automatic insertion into the Lua environment.
|
|
- **eng::malloc heap** — custom deterministic memory allocator for the driven portion, ensuring reproducible addresses during replay.
|
|
|
|
## Architecture: Determinism
|
|
|
|
The driven portion must be fully deterministic so that synchronous models stay in lockstep and event replay works. Rules: no true random numbers, no iterating unordered maps, no real-time clocks, no threads (with carefully sandboxed exceptions). See `Docs/The-Event-Driven-Structure-of-the-Engine.md`.
|
|
|
|
## Architecture: GUI System
|
|
|
|
Blueprints call into Lua via two mechanisms:
|
|
- **Invokes** — change world state, forwarded to server, executed in order per predictive reexecution rules.
|
|
- **Probes** — read-only, return data to blueprints, run locally on client.
|
|
|
|
Look-at widgets, hotkeys, and menus are built on top of this. The menu system is implemented entirely in "user space" Lua and blueprint code. See `Docs/Displaying-Widget-Blueprints.md`.
|
|
|
|
## Blueprint Text Export
|
|
|
|
Blueprints are automatically exported to readable text files in `Saved/BlueprintExports/` whenever they are saved in the editor. This lets Claude Code read blueprint logic. See `Docs/Blueprint Text Export.md` for format details. Source: `Source/Integration/BlueprintExporter.h/.cpp` and `Source/Integration/Integration.cpp`.
|
|
|
|
## Key Documentation
|
|
|
|
Look in the Docs directory for important documentation.
|
|
|
|
## Git
|
|
|
|
Do not use git to make changes (commit, push, branch, etc.). Read-only git commands (status, log, diff, etc.) are fine.
|
|
|
|
## Workflow
|
|
|
|
- When the user gives a direct command, execute it. But when proposing changes on your own initiative, describe the plan and get approval before editing files.
|
|
|
|
## Coding Conventions
|
|
|
|
- Prefer early returns and `continue` to reduce nesting (never-nester style).
|
|
- Do not use static functions in Unreal code. Use class methods or namespace-scoped functions instead.
|
|
- Use `LogLuprexIntegration` for log messages, not `LogTemp`.
|
|
- When writing UFUNCTIONs that take an `AActor*`, `UObject*`, or similar "self" parameter, add `DefaultToSelf` meta to that pin. Most functions should have this on the obvious pin so the user doesn't have to manually wire it in blueprints.
|
|
|
|
## Session Startup
|
|
|
|
At the beginning of every session, do a directory listing of these three directories so you know what files are available:
|
|
- `Docs/` — documentation
|
|
- `Source/Integration/` — Unreal-side C++ code
|
|
- `luprex/cpp/core/` — Luprex DLL core C++ code
|
|
|
|
These two code directories contain 99% of the code we'll be working on together.
|
|
|
|
## Current Status
|
|
|
|
(Use this section to track what we're working on across sessions.)
|