Introduction

In the programming I usually do, a game loop is not necessary. However, it is necessary when programing games.

I'm going to share some insights from my experience implementing a game loop with Rust and WASM.

Play in browser

Source

What I learned

Here are the websites I referred to when coding the game loop.

• The code has implemented a sophisticated technique to synchronize rendering with the browser's actual frame rate.

const FRAME_SIZE: f64 = 1.0 / 60.0 * 1000.0;

while game_loop.accumulated_delta > FRAME_SIZE {
    game.update(&keystate);
    game_loop.accumulated_delta -= FRAME_SIZE;
}
game_loop.last_frame = perf;
game.draw(&renderer);

• Rust ownership, particularly the concept of borrowing and lifetimes, is crucial for understanding this implementation.

impl GameLoop {
    let f: SharedLoopClosure = Rc::new(RefCell::new(None));
    let g = f.clone();
    let mut keystate = KeyState::new();
    *g.borrow_mut() = Some(browser::create_raf_closure(move |perf: f64| {
        let _= browser::request_animation_frame(f.borrow().as_ref().unwrap());
    }));
    browser::request_animation_frame(
        g.borrow()
            .as_ref()
            .ok_or_else(|| anyhow!("GameLoop: Loop is None"))?,
    )?;
    Ok(())
}

What was fun experience

Forty years ago, my first personal computer was an MSX2. I enjoyed programming by typing in the source code published in BASIC Magazine. The first program I typed was a racing game similar to the one I've created recently. Though my memory is a bit hazy, I recall the walls being represented by "#" and the car by a diamond character "♢". I remember spending hours correcting typos while referencing the magazine's source code. The joy I felt when the copied program finally ran is something I'll never forget. The excitement of seeing a program come to life hasn't changed at all, even now.

Reference

Game-Development-with-Rust-and-WebAssembly

Browser Frame rate(FPS)