# Objective Continue improving the user experience of our UI Node API in the direction specified by [Bevy's Next Generation Scene / UI System](https://github.com/bevyengine/bevy/discussions/14437) ## Solution As specified in the document above, merge `Style` fields into `Node`, and move "computed Node fields" into `ComputedNode` (I chose this name over something like `ComputedNodeLayout` because it currently contains more than just layout info. If we want to break this up / rename these concepts, lets do that in a separate PR). `Style` has been removed. This accomplishes a number of goals: ## Ergonomics wins Specifying both `Node` and `Style` is now no longer required for non-default styles Before: ```rust commands.spawn(( Node::default(), Style { width: Val::Px(100.), ..default() }, )); ``` After: ```rust commands.spawn(Node { width: Val::Px(100.), ..default() }); ``` ## Conceptual clarity `Style` was never a comprehensive "style sheet". It only defined "core" style properties that all `Nodes` shared. Any "styled property" that couldn't fit that mold had to be in a separate component. A "real" style system would style properties _across_ components (`Node`, `Button`, etc). We have plans to build a true style system (see the doc linked above). By moving the `Style` fields to `Node`, we fully embrace `Node` as the driving concept and remove the "style system" confusion. ## Next Steps * Consider identifying and splitting out "style properties that aren't core to Node". This should not happen for Bevy 0.15. --- ## Migration Guide Move any fields set on `Style` into `Node` and replace all `Style` component usage with `Node`. Before: ```rust commands.spawn(( Node::default(), Style { width: Val::Px(100.), ..default() }, )); ``` After: ```rust commands.spawn(Node { width: Val::Px(100.), ..default() }); ``` For any usage of the "computed node properties" that used to live on `Node`, use `ComputedNode` instead: Before: ```rust fn system(nodes: Query<&Node>) { for node in &nodes { let computed_size = node.size(); } } ``` After: ```rust fn system(computed_nodes: Query<&ComputedNode>) { for computed_node in &computed_nodes { let computed_size = computed_node.size(); } } ```
		
			
				
	
	
		
			70 lines
		
	
	
		
			2.0 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			70 lines
		
	
	
		
			2.0 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! Uses two windows to visualize a 3D model from different angles.
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use bevy::{prelude::*, render::camera::RenderTarget, window::WindowRef};
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fn main() {
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    App::new()
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        // By default, a primary window gets spawned by `WindowPlugin`, contained in `DefaultPlugins`
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        .add_plugins(DefaultPlugins)
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        .add_systems(Startup, setup_scene)
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        .run();
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}
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fn setup_scene(mut commands: Commands, asset_server: Res<AssetServer>) {
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    // add entities to the world
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    commands.spawn(SceneRoot(
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        asset_server.load(GltfAssetLabel::Scene(0).from_asset("models/torus/torus.gltf")),
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    ));
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    // light
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    commands.spawn((
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        DirectionalLight::default(),
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        Transform::from_xyz(3.0, 3.0, 3.0).looking_at(Vec3::ZERO, Vec3::Y),
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    ));
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    let first_window_camera = commands
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        .spawn((
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            Camera3d::default(),
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            Transform::from_xyz(0.0, 0.0, 6.0).looking_at(Vec3::ZERO, Vec3::Y),
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        ))
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        .id();
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    // Spawn a second window
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    let second_window = commands
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        .spawn(Window {
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            title: "Second window".to_owned(),
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            ..default()
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        })
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        .id();
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    let second_window_camera = commands
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        .spawn((
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            Camera3d::default(),
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            Transform::from_xyz(6.0, 0.0, 0.0).looking_at(Vec3::ZERO, Vec3::Y),
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            Camera {
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                target: RenderTarget::Window(WindowRef::Entity(second_window)),
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                ..default()
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            },
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        ))
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        .id();
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    let node = Node {
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        position_type: PositionType::Absolute,
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        top: Val::Px(12.0),
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        left: Val::Px(12.0),
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        ..default()
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    };
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    commands.spawn((
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        Text::new("First window"),
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        node.clone(),
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        // Since we are using multiple cameras, we need to specify which camera UI should be rendered to
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        TargetCamera(first_window_camera),
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    ));
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    commands.spawn((
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        Text::new("Second window"),
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        node,
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        TargetCamera(second_window_camera),
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    ));
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}
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