Emscripten Main Loop Helper Library

Documentation

Purpose

Many interactive applications such as games will utilise the technique of having a main loop. This loop will represent one "tick" of the simulation and often also capture input and render output. However, the typical implementation of this technique (simple loop/while statement) breaks down when targeting Emscripten since naive looping will cause the browser tab to freeze up. This library provides a simple trait to use as a replacement for that loop statement and will make sure that the looping is happening in the way that Emscripten needs it to.

Usage

Add emscripten_main_loop as a dependency to your Cargo.toml.

Implement the emscripten_main_loop::MainLoop trait for your application object that contains all the data that should be accessible to the main loop. The trait will require you to implement the main_loop function which is where you are meant to put your looping logic. main_loop will be called once per loop iteration and must return either MainLoopEvent::Continue or MainLoopEvent::Terminate as appropriate.

When the trait is implemented, you can invoke the looping by passing your data object to emscripten_main_loop::run(). See the documentation for further information, or check out this example project as a reference, which uses this library.

I don't know how to use Emscripten yet

For a comprehensive guide on how to use Emscripten to build a project using Rust+SDL2+OpenGL for the web, check out my blog post.

I think this library can be improved

Feel free to raise issues or pull requests as desired, contributions would be appreciated.