WebAssembly
Rust, SDL2, OpenGL, Wasm
Check out rust_sdl2_opengl_emscripten repo. Some things to keep in mind:
Emscripten version
At the time of writing, due to LLVM related compatibility stuff, Rust projects build with Emscripten version 1.39.20. To use this specific version:
git clone https://github.com/emscripten-core/emsdk.git
cd emsdk
./emsdk install 1.39.20
./emsdk activate 1.39.20
source ./emsdk_env.sh