Function ggez::timer::check_update_time

pub fn check_update_time(ctx: &mut Context, target_fps: u32) -> bool

Check whether or not the desired amount of time has elapsed since the last frame.

This function will return true if the time since the last update() call has been equal to or greater to the update FPS indicated by the target_fps. It keeps track of fractional frames, so if you want 60 fps (16.67 ms/frame) and the game stutters so that there is 40 ms between update() calls, this will return true twice in a row even in the same frame, then taking into account the residual 6.67 ms to catch up to the next frame before returning true again.

The intention is to for it to be called in a while loop in your update() callback:

fn update(&mut self, ctx: &mut Context) -> GameResult {
    while(timer::check_update_time(ctx, 60)) {
        update_game_physics()?;
    }
    Ok(())
}