Install for the Web

raylib-rs targets wasm32-unknown-emscripten, which compiles your game to WebAssembly and runs it in a browser via OpenGL ES 2 (WebGL). This path is build-verified continuously in the web.yml CI workflow.

Prerequisites

1. Rust 1.85+ — install via rustup.

2. The wasm32-unknown-emscripten target:

   rustup target add wasm32-unknown-emscripten
   

3. emsdk 3.1.64+ — the Emscripten SDK provides emcc, the compiler that cross-compiles C to WebAssembly. Follow the official emsdk install instructions:

   git clone https://github.com/emscripten-core/emsdk.git
   cd emsdk
   ./emsdk install 3.1.64
   ./emsdk activate 3.1.64
   source ./emsdk_env.sh   # add emcc to PATH for this shell session
   

Required environment variable

The raylib-sys build script requires EMCC_CFLAGS to be set when targeting wasm32-unknown-emscripten. Set it before building:

export EMCC_CFLAGS="-O3 -sUSE_GLFW=3 -sASSERTIONS=1 -sWASM=1 -sASYNCIFY -sGL_ENABLE_GET_PROC_ADDRESS=1"

This exact value is used by the CI web.yml workflow.

Build

cargo build -p raylib --target wasm32-unknown-emscripten

This compiles the raylib crate (and the vendored raylib C source) for the WebAssembly target.

Running in a browser

A cargo build produces a .wasm binary and a .js glue file, but running in a browser also requires an HTML shell that loads them. raylib provides an HTML shell template. The WS9 showcase site (the final workstream of the 6.0 upgrade) will provide working web examples and a reference HTML shell.

Known limitation

The software_renderer feature (PLATFORM=Memory / rlsw) is not currently supported on wasm32-unknown-emscripten. The software renderer is a headless desktop-testing path; WebAssembly uses WebGL (GLES2), not the CPU-only rlsw backend. This is a tracked-deferred item from WS6b; see docs/superpowers/notes/ws6b-complete.md item 5.