new.rs

impl<'a, W: Window>
Iterator<Event>
for EventIterator<'a, W> {
    /// Returns the next game event.
    fn next(&mut self) -> Option<Event> {
        loop {
            self.state = match self.state {
                RenderState => {
                    if self.window.should_close() { return None; }

                    let start_render = time::precise_time_ns();
                    self.last_frame = start_render;

                    let (w, h) = self.window.get_size();
                    if w != 0 && h != 0 {
                        // Swap buffers next time.
                        self.state = SwapBuffersState;
                        return Some(Render(
                            // Extrapolate time forward to allow smooth motion.
                            ext_dt: (start_render - self.last_update) as f64 / billion as f64,
                            width: w,
                            height: h,
                        ));
                    }

                    UpdateLoopState
                }
                SwapBuffersState => {
                    self.window.swap_buffers();
                    UpdateLoopState
                }
                UpdateLoopState => {
                    let current_time = time::precise_time_ns();
                    let next_frame = self.last_frame + self.dt_frame_in_ns;
                    let next_update = self.last_update + self.dt_update_in_ns;
                    let next_event = cmp::min(next_frame, next_update);
                    if next_event > current_time {
                        sleep( Duration::nanoseconds((next_event - current_time) as i64) );
                        UpdateLoopState
                    } else if next_event == next_frame {
                        RenderState
                    } else {
                        HandleEventsState
                    }
                }
                HandleEventsState => {
                    // Handle all events before updating.
                    match self.window.poll_event() {
                        None => UpdateState,
                        Some(x) => { return Some(Input(x)); },
                    }
                }
                UpdateState => {
                    self.state = UpdateLoopState;
                    self.last_update += self.dt_update_in_ns;
                    return Some(Update(dt: self.dt));
                }
            };
        }
    }
}

old.rs

impl<'a, W: Window>
Iterator<Event>
for EventIterator<'a, W> {
    /// Returns the next game event.
    fn next(&mut self) -> Option<Event> {
        loop {
            self.state = match self.state {
                RenderState => {
                    if self.window.should_close() { return None; }

                    let start_render = time::precise_time_ns();
                    self.last_frame = start_render;

                    let (w, h) = self.window.get_size();
                    if w != 0 && h != 0 {
                        // Swap buffers next time.
                        self.state = SwapBuffersState;
                        return Some(Render(RenderArgs {
                            // Extrapolate time forward to allow smooth motion.
                            ext_dt: (start_render - self.last_update) as f64 / billion as f64,
                            width: w,
                            height: h,
                        }));
                    }

                    UpdateLoopState
                }
                SwapBuffersState => {
                    self.window.swap_buffers();
                    UpdateLoopState
                }
                UpdateLoopState => {
                    let current_time = time::precise_time_ns();
                    let next_frame = self.last_frame + self.dt_frame_in_ns;
                    let next_update = self.last_update + self.dt_update_in_ns;
                    let next_event = cmp::min(next_frame, next_update);
                    if next_event > current_time {
                        sleep( Duration::nanoseconds((next_event - current_time) as i64) );
                        UpdateLoopState
                    } else if next_event == next_frame {
                        RenderState
                    } else {
                        HandleEventsState
                    }
                }
                HandleEventsState => {
                    // Handle all events before updating.
                    match self.window.poll_event() {
                        None => UpdateState,
                        Some(x) => { return Some(Input(x)); },
                    }
                }
                UpdateState => {
                    self.state = UpdateLoopState;
                    self.last_update += self.dt_update_in_ns;
                    return Some(Update(UpdateArgs{ dt: self.dt }));
                }
            };
        }
    }
}