bevy/examples/animation/animation_events.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

116 lines
3 KiB
Rust

//! Demonstrate how to use animation events.
use bevy::{
color::palettes::css::{ALICE_BLUE, BLACK, CRIMSON},
core_pipeline::bloom::Bloom,
prelude::*,
};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_event::<MessageEvent>()
.add_systems(Startup, setup)
.add_systems(PreUpdate, (animate_text_opacity, edit_message))
.run();
}
#[derive(Component)]
struct MessageText;
#[derive(Event, Reflect, Clone)]
#[reflect(AnimationEvent)]
struct MessageEvent {
value: String,
color: Color,
}
// AnimationEvent can also be derived, but doing so will
// trigger it as an observer event which is triggered in PostUpdate.
// We need to set the message text before that so it is
// updated before rendering without a one frame delay.
impl AnimationEvent for MessageEvent {
fn trigger(&self, _time: f32, _weight: f32, _entity: Entity, world: &mut World) {
world.send_event(self.clone());
}
}
fn edit_message(
mut event_reader: EventReader<MessageEvent>,
text: Single<(&mut Text2d, &mut TextStyle), With<MessageText>>,
) {
let (mut text, mut style) = text.into_inner();
for event in event_reader.read() {
text.0 = event.value.clone();
style.color = event.color;
}
}
fn setup(
mut commands: Commands,
mut animations: ResMut<Assets<AnimationClip>>,
mut graphs: ResMut<Assets<AnimationGraph>>,
) {
// Camera
commands.spawn((
Camera2d,
Camera {
clear_color: ClearColorConfig::Custom(BLACK.into()),
hdr: true,
..Default::default()
},
Bloom {
intensity: 0.4,
..Bloom::NATURAL
},
));
// The text that will be changed by animation events.
commands.spawn((
MessageText,
Text2d::default(),
TextStyle {
font_size: 119.0,
color: Color::NONE,
..default()
},
));
// Create a new animation clip.
let mut animation = AnimationClip::default();
// This is only necessary if you want the duration of the
// animation to be longer than the last event in the clip.
animation.set_duration(2.0);
// Add events at the specified time.
animation.add_event(
0.0,
MessageEvent {
value: "HELLO".into(),
color: ALICE_BLUE.into(),
},
);
animation.add_event(
1.0,
MessageEvent {
value: "BYE".into(),
color: CRIMSON.into(),
},
);
// Create the animation graph.
let (graph, animation_index) = AnimationGraph::from_clip(animations.add(animation));
let mut player = AnimationPlayer::default();
player.play(animation_index).repeat();
commands.spawn((AnimationGraphHandle(graphs.add(graph)), player));
}
// Slowly fade out the text opacity.
fn animate_text_opacity(mut styles: Query<&mut TextStyle>, time: Res<Time>) {
for mut style in &mut styles {
let a = style.color.alpha();
style.color.set_alpha(a - time.delta_seconds());
}
}