aee/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Aventures En Egipte (AEE) — a retro-style 2D game written in C++ using SDL3. The game uses a software-rendered 8-bit paletted graphics engine (320x200, 256 colors), custom audio (JailAudio), and GIF-based assets. The codebase and commit messages are in Valencian/Catalan.

Build

# Linux
cmake -B build
cmake --build build

# Windows (MinGW)
cmake -B build -G "MinGW Makefiles"
cmake --build build

Dependencies: SDL3. Uses CMake (minimum 3.10) with C++20. SPIR-V shaders compiled automatically if glslc is available; precompiled headers used as fallback.

The executable is output to the project root. The data/ folder must be in the working directory at runtime.

Architecture

Golden Rule: Do Not Touch Gameplay

The original game logic (gameplay, entities, map, scoring, collisions, animations) must remain untouched. All modernization work targets the presentation layer and infrastructure only. Any new feature must be implemented as an overlay on top of the existing game, never by modifying original gameplay code.

Boundary: Original vs New Code

Path	Owner	Rule
source/core/jail/	Original engine	Do not modify gameplay behavior
source/game/*.cpp/hpp (except options/defines/defaults)	Original game	Do not modify
source/core/rendering/	New presentation layer	Free to modify
source/core/input/	New input layer	Free to modify
source/utils/	New utilities	Free to modify
source/game/options,defines,defaults	New config system	Free to modify
data/*.gif, *.ogg	Original assets	Do not modify
data/fonts/, data/ui/, data/shaders/	New assets	Free to modify

Original "Jail" Engine (source/core/jail/)

Flat C-style APIs (no classes), prefixed by subsystem. Do not touch gameplay logic.

• JG (jgame) — Game loop timing: init/finalize, fixed-timestep update via JG_ShouldUpdate()
• JD8 (jdraw8) — 8-bit paletted software renderer. 320x200 screen buffer (JD8_Surface = Uint8*), palette-indexed blitting with color-key transparency, fade effects. JD8_Flip() converts palette→ARGB and delegates to Screen::present()
• JA (jail_audio) — Custom audio mixing using SDL3 audio streams (OGG via stb_vorbis, WAV)
• JI (jinput) — Input: keyboard state polling, key debouncing, cheat code detection. Filters GUI keys from game, calls GlobalInputs::handle() and Mouse::updateCursorVisibility() each update
• JF (jfile) — File I/O: filesystem folder mode (data/) or packed resource file (.jrf). Config folder at ~/.config/jailgames/aee/

System Layer (source/core/system/)

• Director (director.hpp/cpp) — Orchestrator singleton. Owns main thread. Launches game thread that runs ModuleGame/ModuleSequence::Go(). Emulator-style architecture: Director runs at ~60 FPS independently, polls SDL events, updates overlay, presents frames. Game thread blocks at JD8_Flip() → Director::publishFrame() until Director consumes the frame. Director is non-blocking: if no new frame is available, it re-presents the last known game frame with fresh overlay on top

Presentation Layer (source/core/rendering/)

• Screen (screen.hpp/cpp) — Singleton. Manages SDL_Window, SDL_Renderer, SDL_Texture. Dual rendering path: SDL3GPU with shaders (primary) or SDL_Renderer fallback. Handles fullscreen, zoom, aspect ratio 4:3, integer scaling, VSync. Counts FPS and updates render info text
• Overlay (overlay.hpp/cpp) — Paints directly on the ARGB pixel buffer before presentation. Handles notifications (slide-in animation), render info display (top/bottom/off, configurable colors), and double-ESC-to-quit logic
• Text (text.hpp/cpp) — Bitmap font renderer. Loads .fnt + .gif pairs, renders UTF-8 glyphs directly on Uint32* ARGB buffer. No dependency on SDL_Texture or palettes
• SDL3GPUShader (sdl3gpu/) — GPU shader backend (Vulkan/Metal). PostFX and CRT-Pi shaders with presets, supersampling (3×/6×/9×), Lanczos downscaling. Supports 4:3 aspect ratio stretch fused into the upscale pass to avoid artifacts

Input Layer (source/core/input/)

• GlobalInputs (global_inputs.hpp/cpp) — Maps configurable function keys to presentation actions. Uses debounce. Returns whether a key was consumed (to suppress from game layer)
• Mouse (mouse.hpp/cpp) — Auto-hides cursor after 3 seconds of inactivity

Configuration System (source/game/)

Follows the pattern from jaildoctors_dilemma, persists to YAML:

• defines.hpp — Game constants: Texts::WINDOW_TITLE, Texts::VERSION, GameScreen::WIDTH/HEIGHT
• defaults.hpp — Default values: Defaults::KeysGUI, Defaults::KeysGame, Defaults::Video, Defaults::Audio, Defaults::Window, Defaults::Game
• options.hpp/cpp — Options namespace with inline globals and YAML load/save. Structs: KeysGUI, KeysGame, Video, RenderInfo, Audio, Window, Game, PostFXPreset, CrtPiPreset

Utilities (source/utils/)

• utils.hpp/cpp — toLower() and other helpers

Function Key Map

Key	Action
F1	Decrease window zoom
F2	Increase window zoom
F3	Toggle fullscreen
F4	Toggle shaders on/off
F5	Toggle aspect ratio (square pixels ↔ 4:3 CRT)
F6	Toggle supersampling
F7	Cycle shader type (PostFX ↔ CRT-Pi)
F8	Cycle shader presets
F9	Toggle stretch filter (nearest ↔ linear)
F10	Cycle render info (off → top → bottom → off)
ESC	Double-press to quit (with overlay notification)

All key bindings are configurable via Options::keys_gui and stored in config.yaml.

Threading Model (Emulator Architecture)

Main thread (Director)              Game thread (ModuleGame/Sequence::Go())
────────────────────                ────────────────────────────────────
loop at ~60 FPS {                   loop {
  SDL_PollEvent()                     ... game logic ...
  GlobalInputs, Mouse                 JD8_Flip():
  if new_frame_available:               palette→ARGB in pixel_data
    copy to game_frame                  publishFrame(pixel_data)  ⏸
    signal → ────────────────────→      (blocks until Director consumes)
  copy game_frame → present_buffer      ←──── signal_consumed
  Overlay::render(present_buffer)       continue game loop
  Screen::present(present_buffer)     }
  SDL_Delay to hit 60fps
}

Key points:

• Director is NON-BLOCKING: if no new frame, re-presents the last one with fresh overlay
• Double buffer: game_frame (untouched copy from game) + presentation_buffer (regenerated with overlay each frame)
• Game thread pauses at JD8_Flip() waiting for Director — natural sync point
• SDL events processed ONLY on main thread (SDL requirement)
• JI_Update() no longer polls events — reads Director's state

Rendering Pipeline (inside Screen::present)

Screen::present(pixel_data):
  1. FPS count + render info text update
  2. IF GPU + shaders enabled:
     - uploadPixels → scene_texture (320×200)
     - [IF 4:3] stretch pass fused with upscale: scene → scaled_texture (W×factor, H×factor×1.2)
     - [IF SS] upscale pass: scene → scaled_texture (W×factor, H×factor)
     - PostFX or CRT-Pi shader → swapchain (with viewport letterboxing)
  3. ELSE IF GPU without shaders:
     - uploadPixels → clean render → swapchain
  4. ELSE (fallback):
     - SDL_UpdateTexture → SDL_RenderPresent

Pixel Format

JD8_Flip produces ABGR byte order: 0xFF000000 + R + (G<<8) + (B<<16). SDL texture uses SDL_PIXELFORMAT_ABGR8888. GPU textures use SDL_GPU_TEXTUREFORMAT_R8G8B8A8_UNORM (same byte layout on little-endian). Overlay colors are ABGR format.

Persistence Files

File	Content
~/.config/jailgames/aee/config.yaml	Main config (video, audio, window, render_info, game, shader selection)
~/.config/jailgames/aee/postfx.yaml	PostFX shader presets (6 defaults: CRT, NTSC, CURVED, SCANLINES, SUBTLE, CRT LIVE)
~/.config/jailgames/aee/crtpi.yaml	CRT-Pi shader presets (4 defaults: DEFAULT, CURVED, SHARP, MINIMAL)

External Libraries (source/external/)

• gif.h — Header-only GIF decoder. Cannot be included from more than one .cpp (no include guards on functions). Other files use extern declarations for LoadGif()
• stb_vorbis.h — stb single-header OGG decoder
• fkyaml_node.hpp — Header-only YAML parser (fkYAML v0.4.2)

Data Assets (data/)

• *.gif, *.ogg — Original game assets (do not modify)
• fonts/8bithud.fnt + .gif — Bitmap font for overlay (8×8, 124 glyphs, UTF-8 with accents)
• shaders/ — GLSL sources: postfx.vert, postfx.frag, upscale.frag, downscale.frag, crtpi_frag.glsl
• ui/ — Reserved for future UI graphics

Known Issues & Technical Debt

1. gif.h cannot be included twice: Functions are not static or inline, causing multiple definition errors. Text class uses extern forward declarations as workaround

Previously Fixed (kept for reference)

• ESC double-press: Fixed by intercepting KEY_DOWN in Director, setting atomic esc_blocked_ immediately. JI_KeyPressed(ESCAPE) consults this flag. No race condition possible because Director's flag wins before game polls
• Overlay freeze during intros: Fixed by threading model. Director runs independently at 60 FPS regardless of game delays. Double buffer avoids overlay smearing on re-presented frames

Main Entry (source/main.cpp)

Init order: file_setconfigfolder → Options::load → Options::loadPostFX/CrtPi → JG_Init → Screen::init → JD8_Init → JA_Init → Overlay::init → Director::init → Director::run() (blocks until quit). Shutdown: Options::save → Director::destroy → Overlay::destroy → JA_Quit → JD8_Quit → Screen::destroy → JG_Finalize.

The state machine (alternating ModuleSequence state=1 and ModuleGame state=0) now lives inside Director::gameThreadFunc(), running on the game thread.