bevy/examples/ui/window_fallthrough.rs
Carter Anderson 015f2c69ca
Merge Style properties into Node. Use ComputedNode for computed properties. (#15975)
# 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();
    }
}
```
2024-10-18 22:25:33 +00:00

54 lines
2.1 KiB
Rust

//! This example illustrates how have a mouse's clicks/wheel/movement etc fall through the spawned transparent window to a window below.
//! If you build this, and hit 'P' it should toggle on/off the mouse's passthrough.
//! Note: this example will not work on following platforms: iOS / Android / Web / X11. Window fall through is not supported there.
use bevy::prelude::*;
fn main() {
App::new()
.insert_resource(ClearColor(Color::NONE)) // Use a transparent window, to make effects obvious.
.add_plugins(DefaultPlugins.set(WindowPlugin {
primary_window: Some(Window {
// Set the window's parameters, note we're setting the window to always be on top.
transparent: true,
decorations: true,
window_level: bevy::window::WindowLevel::AlwaysOnTop,
..default()
}),
..default()
}))
.add_systems(Startup, setup)
.add_systems(Update, toggle_mouse_passthrough) // This allows us to hit 'P' to toggle on/off the mouse's passthrough
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// UI camera
commands.spawn(Camera2d);
// Text with one span
commands.spawn((
// Accepts a `String` or any type that converts into a `String`, such as `&str`
Text::new("Hit 'P' then scroll/click around!"),
TextFont {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 83.0, // Nice and big so you can see it!
..default()
},
// Set the style of the TextBundle itself.
Node {
position_type: PositionType::Absolute,
bottom: Val::Px(5.),
right: Val::Px(10.),
..default()
},
));
}
// A simple system to handle some keyboard input and toggle on/off the hittest.
fn toggle_mouse_passthrough(
keyboard_input: Res<ButtonInput<KeyCode>>,
mut window: Single<&mut Window>,
) {
if keyboard_input.just_pressed(KeyCode::KeyP) {
window.cursor_options.hit_test = !window.cursor_options.hit_test;
}
}