Web export

Games export to the web as a folder you can upload anywhere that serves static files (itch.io, GitHub Pages, your own site):

Browser/
├── index.html      the page: a start screen, then the game in a canvas
├── index.js        emscripten's loader
├── index.wasm      the engine (Odin) + raylib + Lua + Box2D, compiled to WebAssembly
├── odin.js         Odin's browser runtime
├── game.rayzr      your game (the same package the desktop exports use)
├── fonts/          the UI font
└── favicon.png     your project icon (when it has one)

Exporting

1. Project Settings > Export: add a preset with platform web (or tick web among the targets). Its window title becomes the page title.
2. Save and Export This Preset (or File > Export > Standalone Game).
3. File > Export > Open Web Export in Browser serves the folder on http://127.0.0.1:8765/ and opens it - browsers don’t run WebAssembly from file:// pages, so double-clicking index.html doesn’t work.

To publish on itch.io: zip the folder’s contents, upload it as an HTML project, tick “This file will be played in the browser”.

In the browser

• Click to play: browsers only allow sound after a click (or key), so the page shows a start screen. index.html?autostart skips it (kiosks; sound may stay off until the page is clicked).
• The game fills the window and keeps its virtual resolution (letterboxed), like the desktop runner.
• Saves (Save.*, input bindings, accessibility settings) go to /save, kept in the browser’s IndexedDB - they survive reloads, per site.
• Keyboard, mouse, gamepads (the browser’s Gamepad API), audio (all formats, the mixer and its effects), Lua scripts, physics, shaders (materials, post effects, lighting - converted to WebGL 2’s GLSL ES 300), sprite atlases and QOI textures work as on the desktop.

Not on the web

• Threads: textures decode on the main thread (loading screens still report progress, but a big preload stalls frames).
• Files outside the package, directory listings, Engine.quit() (a page can’t close itself), the native file dialogs.
• Hot reload and the editor link (Play in the editor runs the desktop game).

The web runner (for engine developers)

Exporting copies a prebuilt runner - no compiler is needed. The runner is built once with emscripten:

brew install emscripten          # (or the emsdk)
scripts/build_web_runner.sh      # -> bin/runners/web/

It downloads and builds raylib 5.5 (WebGL 2), Lua 5.4.7 and Box2D 3.1.1 with emcc (once, into bin/web_deps/), compiles the engine for js_wasm32 (scripts/web_prepare.py makes a patched copy of the sources: the web versions of a few packages, below) and links it with the page shell scripts/web/shell.html. scripts/build_runners.sh builds it too when emcc is installed.

Shipping the editor: put runners/web/ (the four runner files) next to the editor, like runners/macos/ etc. Users then export to the web without installing emscripten or Odin.

How the engine runs on the web:

	Desktop	Web
Main loop	Engine_RunProject loops	the page calls main_update each animation frame (Runner_Start / Runner_Frame / Runner_Stop)
Files	core:os	engine/osx (emscripten’s libc over its file system); engine/pathx for paths
Memory	the C heap, virtual-memory arenas	emscripten’s malloc (Engine_HeapAllocator, Engine_DefaultContext), malloc arenas (engine/vmemx); built with -default-to-panic-allocator so nothing grows memory behind emscripten’s back
Lua bindings	engine/lua54 (Odin’s vendor bindings, copied)	the same, linking the emcc-built Lua
Shaders	GLSL 330	Shader_Port: GLSL ES 300
Texture decoding	worker threads	the main thread

node scripts/web/capture.mjs URL out.png [seconds] runs a page in headless Chrome and prints its console - the web test drive uses it.

Limits

• WebGL 2 is required (every current browser).
• The web build compiles a patched copy of the ui/ package; if that package gains new OS-specific code, scripts/web_prepare.py may need a new patch.