bevy: 200-250ms lag on 'mouse down' events on macOS

Bevy version 0.8

Relevant system information

macOS Monterey

What you did

I found that mouse click events were delayed in my game.

Here is the example: https://github.com/bevyengine/bevy/blob/latest/examples/input/mouse_input.rs

What went wrong

To reproduce this, I ran the bare-bones bevy input example linked below, and get the same result. With some logging I found the delay for mouse down is consistently 200-250ms. However there is 0 delay for mouse up.

Additional information

Since delayed mouse input is a deal-breaker for the use of Bevy for me, I spent quite a white trying to reproduce this.

I created a bare-bones example using Winit (not bevy at all) and mouse down and mouse up are instant - no delay, so i do not think there is an issue there.

I replicated Bevy locally and started commenting things out to see if i could isolate the issue, and if i comment out the following, there is no delay, so i assume the culprit is in there somewhere:

https://github.com/bevyengine/bevy/blob/latest/crates/bevy_winit/src/lib.rs

Comment out the body of the event::Event::MainEventsCleared => { match case, eg:

        event::Event::MainEventsCleared => {
            handle_create_window_events(
                &mut app.world,
                event_loop,
                &mut create_window_event_reader,
            );
            let winit_config = app.world.resource::<WinitSettings>();
            let update = if winit_state.active {
                let windows = app.world.resource::<Windows>();
                let focused = windows.iter().any(|w| w.is_focused());
                match winit_config.update_mode(focused) {
                    UpdateMode::Continuous | UpdateMode::Reactive { .. } => true,
                    UpdateMode::ReactiveLowPower { .. } => {
                        winit_state.low_power_event
                            || winit_state.redraw_request_sent
                            || winit_state.timeout_reached
                    }
                }
            } else {
                false
            };
            if update {
                winit_state.last_update = Instant::now();
                app.update();
            }
        }

Thanks for reading and thanks for the lovely game engine, I hope to be able to use it 😃

About this issue

Original URL
State: closed
Created 2 years ago
Comments: 18 (6 by maintainers)

Most upvoted comments

Ok! I appear to have stumbled across the culprit: I run an app called ‘magnet’ on my macs that gives keyboard shortcuts for moving your windows around. For some reason, when this is running, i have the delay, and when it is not running, there is no delay. I’ll see if the developers of that app can fix it.

Here’s the app: https://apps.apple.com/au/app/magnet/id441258766?mt=12

I’m terribly sorry to have wasted your time!

chrishulbert on Aug 30, 2022

nice to hear you found the source of the delay!

mockersf on Aug 30, 2022

There is no problem on my platform:

Rust: rustc 1.63.0 (4b91a6ea7 2022-08-08)
OS:
- Model Name: MacBook Pro
- Model Identifier: MacBookPro18,3
- Chip: Apple M1 Pro
- Total Number of Cores: 8 (6 performance and 2 efficiency)
- Memory: 16 GB
- OS Loader Version: 7429.61.2
Bevy: 0.8.1

zyxkad on Aug 29, 2022

If i revert all my comments in bevy_winit/src/lib.rs, thus use vanilla bevy, and instead put the following in my main.rs, the lag goes away:

fn main() {
    App::new()
        .insert_resource(WinitSettings {
            focused_mode: UpdateMode::ReactiveLowPower { max_wait: Duration::from_millis(100) },
            ..default()
        })...

However i’m fairly sure ReactiveLowPower isn’t what I want for an interactive game.

chrishulbert on Aug 24, 2022

Thanks for responding! 😃 Just the default, as per https://github.com/bevyengine/bevy/blob/latest/examples/input/mouse_input.rs

-edit-

I believe the default is as follows:

impl Default for WinitSettings {
    fn default() -> Self {
        WinitSettings {
            return_from_run: false,
            focused_mode: UpdateMode::Continuous,
            unfocused_mode: UpdateMode::Continuous,
        }
    }
}

chrishulbert on Aug 23, 2022