Setting Display::None doesn't hide UI elements

[Pascualex]

Bevy version

0.10

What you did

I updated an old project where I toggle the display of certain UI elements.

What went wrong

Once they were set to Display::Flex for the first time, setting Display::None didn't hide them.

Additional information

I built a minimal repro. The node spawns with Display::None. Pressing space for the first time toggles the display, showing the node. Pressing space a second time toggles the display but doesn't hide the node. This example works as expected when ran with Bevy 0.9.

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_startup_system(spawn_camera_and_node)
        .add_system(toggle_display)
        .run();
}

fn spawn_camera_and_node(mut commands: Commands) {
    commands.spawn(Camera2dBundle::default());
    commands.spawn(NodeBundle {
        style: Style {
            display: Display::None,
            size: Size::new(Val::Percent(100.0), Val::Percent(100.0)),
            ..default()
        },
        background_color: Color::RED.into(),
        ..default()
    });
}

fn toggle_display(mut query: Query<&mut Style>, input: Res<Input<KeyCode>>) {
    if input.just_pressed(KeyCode::Space) {
        let mut style = query.single_mut();
        style.display = match style.display {
            Display::Flex => Display::None,
            Display::None => Display::Flex,
        };
    }
}

[rparrett]

Bisected to 76058bc

[nicoburns]

This one I can reproduce in Taffy. "leaf" display mode for nodes with no children is taking precedence over display: none. Fix incoming. Just trying to work out why our tests didn't catch this as we do have tests specifically testing display: none.

[nicoburns]

Ah. So this bug only triggers if the display: none node is the only node in the hierarchy. If it either has children OR is itself a child of another node then it work fine!

[nicoburns]

@Pascualex Fix submitted in the form of #7953. In the meantime I believe you ought to be able to work around this issue by introducing an extra (useless) UI node. EDIT: while the workaround should work, I believe you can also get access to the new (fixed) version of Taffy by running cargo update which is probably a better solution.

[kelden]

@nicoburns I have an empty menu node that I have created in a startup system with Display::None. It is correctly hidden at first, but when I toggle it to Flex and back to None it stays visible. This happens with or without children nodes, after updating to Taffy 0.3.4 with cargo update.

The minimal example still doesn't work for me after updating with cargo update.

[Pascualex]

@nicoburns that was quick! Thank you.

[Pascualex]

Yeah, @kelden is right, the minimal example is still failing for me too. Even though as you pointed cargo update does update Taffy to 0.3.4.

[nicoburns]

This needs to be reopened, as it's not completely fixed.

[nicoburns]

@Pascualex @kelden Taffy v0.3.5 has now been released which I have confirmed fixes the minimal example for me. You should be able to get it by running cargo update again.

[Pascualex]

@nicoburns yes, it works as expected now. Thanks again!