MouseButton input bug when captured

[nic96]

Bevy version
Commit: 1398d78

Operating system & version

Linux
I have a high DPI display which may or may not be relevant.

What you did

When mouse is captured if you move the mouse to one side mouse button input quits working.

I made an example where whenever you click the ClearColor changes
The first time you click you're mouse will also get captured

Here's a reproducible example:

use bevy::prelude::*;

fn main() {
    App::build()
        .add_resource(ClearColor(Color::rgb_u8(100, 30, 30)))
        .add_resource(ClickCount(0))
        .add_plugins(DefaultPlugins)
        .add_system(capture_mouse_system)
        .add_system(change_color_system)
        .run();
}

struct ClickCount(pub u32);

fn capture_mouse_system(
    keyboard_input: Res<Input<KeyCode>>,
    mouse_input: Res<Input<MouseButton>>,
    mut windows: ResMut<Windows>,
) {
    if let Some(window) = windows.get_primary_mut() {
        if window.cursor_visible() {
            if mouse_input.just_pressed(MouseButton::Left) {
                window.set_cursor_visibility(false);
                window.set_cursor_lock_mode(true);
            }
        } else {
            if keyboard_input.just_pressed(KeyCode::Escape) {
                window.set_cursor_visibility(true);
                window.set_cursor_lock_mode(false);
            }
        }
    }
}

fn change_color_system(
    mut clear_color: ResMut<ClearColor>,
    mouse_input: Res<Input<MouseButton>>,
    mut click_count: ResMut<ClickCount>,
) {
    let colors = [
        Color::rgb_u8(100, 30, 30),
        Color::rgb_u8(30, 100, 30),
        Color::rgb_u8(30, 30, 100),
    ];

    if mouse_input.just_pressed(MouseButton::Left) {
        click_count.0 += 1;
    }

    clear_color.0 = colors[click_count.0 as usize % colors.len()];
}

What you expected to happen

MouseButton input should work no matter how far you move the mouse.

What actually happened

When moving the mouse too far to the side MouseButton input quits working.

[nic96]

I just realized it only quits working when moving the mouse too far to the left. Other directions don't cause the problem
And it's window size dependent so It might be related to the high DPI rounding errors in #1003

[nic96]

I was able to workaround it be setting the cursor position every frame. I think it could possibly be an X11, KDE Plasma, or perhaps winit bug, but I haven't narrowed it down yet. For now I'm fine with just setting the cursor position.

Edit: and it doesn't happen full screen. Only when the window is on the left side of the screen so maybe it has something to do with KDE's cursor screen edge detection.

[Aceeri]

I don't think this is necessarily a bug, since it is more expected behavior that the window shouldn't get mouse events when it leaves the window, in games you might want to lock the cursor using .set_cursor_grab_mode(CursorGrabMode::Locked) or by manually setting cursor position as you said.

[tim-blackbird]

Their example does lock the cursor

[Aceeri]

Ah true, I'm not entirely sure then, I'm guessing that the locking might've been erroring out for whatever reason, I don't think we really logged that before or that was overlooked in the logs?

[nic96]

A bit late but the issue no longer exists with cursor CursorGrabMode::Locked so closing the issue.