Compiling SDL Multiplayer Games to WebAssembly with Emscripten for use in Web Browsers

Abstract: Collecting and deploying online games made by inexperienced developers can behard. This is something KTH (Royal Institute of Technology) has a problem withpertaining to a course involving SDL and SDL_Net programming. A good solutionto this problem is to host these games on a website. An easy-to-use way of compilingand deploying multiplayer games and game-servers written in C as web applicationsand web servers was needed. Specifically for games written in C using SDL andSDL_net libraries. The compiler toolchain Emscripten was used to compile gameand server code from C to WebAssembly, that could then be used through the generated JavaScript functions. Communication between the client and the server washandled by WebSockets. As much of the Emscripten specific functions were to behidden behind C libraries, emulating the format of SDL_Net. The finished solutionsthat emulated the format of SDL_Net, consisted of two new libraries, one for theserver and the other for the client. The libraries successfully emulated the TCP partsof SDL_Net library. The browsers event scheduler necessitates applications to beable to return control back to it. This meant that the game codes endlessly loopingfunctions had to be rewritten to enable rendering in the browser.