bevy/examples/ui/transparency_ui.rs
UkoeHB c2c19e5ae4
Text rework (#15591)
**Ready for review. Examples migration progress: 100%.**

# Objective

- Implement https://github.com/bevyengine/bevy/discussions/15014

## Solution

This implements [cart's
proposal](https://github.com/bevyengine/bevy/discussions/15014#discussioncomment-10574459)
faithfully except for one change. I separated `TextSpan` from
`TextSpan2d` because `TextSpan` needs to require the `GhostNode`
component, which is a `bevy_ui` component only usable by UI.

Extra changes:
- Added `EntityCommands::commands_mut` that returns a mutable reference.
This is a blocker for extension methods that return something other than
`self`. Note that `sickle_ui`'s `UiBuilder::commands` returns a mutable
reference for this reason.

## Testing

- [x] Text examples all work.

---

## Showcase

TODO: showcase-worthy

## Migration Guide

TODO: very breaking

### Accessing text spans by index

Text sections are now text sections on different entities in a
hierarchy, Use the new `TextReader` and `TextWriter` system parameters
to access spans by index.

Before:
```rust
fn refresh_text(mut query: Query<&mut Text, With<TimeText>>, time: Res<Time>) {
    let text = query.single_mut();
    text.sections[1].value = format_time(time.elapsed());
}
```

After:
```rust
fn refresh_text(
    query: Query<Entity, With<TimeText>>,
    mut writer: UiTextWriter,
    time: Res<Time>
) {
    let entity = query.single();
    *writer.text(entity, 1) = format_time(time.elapsed());
}
```

### Iterating text spans

Text spans are now entities in a hierarchy, so the new `UiTextReader`
and `UiTextWriter` system parameters provide ways to iterate that
hierarchy. The `UiTextReader::iter` method will give you a normal
iterator over spans, and `UiTextWriter::for_each` lets you visit each of
the spans.

---------

Co-authored-by: ickshonpe <david.curthoys@googlemail.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
2024-10-09 18:35:36 +00:00

83 lines
2.9 KiB
Rust

//! Demonstrates how to use transparency with UI.
//! Shows two colored buttons with transparent text.
use bevy::prelude::*;
fn main() {
App::new()
.insert_resource(ClearColor(Color::BLACK))
.add_plugins(DefaultPlugins)
.add_systems(Startup, setup)
.run();
}
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
commands.spawn(Camera2d);
let font_handle = asset_server.load("fonts/FiraSans-Bold.ttf");
commands
.spawn(NodeBundle {
style: Style {
width: Val::Percent(100.0),
height: Val::Percent(100.0),
align_items: AlignItems::Center,
justify_content: JustifyContent::SpaceAround,
..default()
},
..default()
})
.with_children(|parent| {
parent
.spawn(ButtonBundle {
style: Style {
width: Val::Px(150.0),
height: Val::Px(65.0),
justify_content: JustifyContent::Center,
align_items: AlignItems::Center,
..default()
},
background_color: Color::srgb(0.1, 0.5, 0.1).into(),
..default()
})
.with_children(|parent| {
parent.spawn((
Text::new("Button 1"),
TextStyle {
font: font_handle.clone(),
font_size: 33.0,
// Alpha channel of the color controls transparency.
color: Color::srgba(1.0, 1.0, 1.0, 0.2),
..default()
},
));
});
// Button with a different color,
// to demonstrate the text looks different due to its transparency.
parent
.spawn(ButtonBundle {
style: Style {
width: Val::Px(150.0),
height: Val::Px(65.0),
justify_content: JustifyContent::Center,
align_items: AlignItems::Center,
..default()
},
background_color: Color::srgb(0.5, 0.1, 0.5).into(),
..default()
})
.with_children(|parent| {
parent.spawn((
Text::new("Button 2"),
TextStyle {
font: font_handle.clone(),
font_size: 33.0,
// Alpha channel of the color controls transparency.
color: Color::srgba(1.0, 1.0, 1.0, 0.2),
..default()
},
));
});
});
}