89cbc78d3d
# Objective Be consistent with `Resource`s and `Components` and have `Event` types be more self-documenting. Although not susceptible to accidentally using a function instead of a value due to `Event`s only being initialized by their type, much of the same reasoning for removing the blanket impl on `Resource` also applies here. * Not immediately obvious if a type is intended to be an event * Prevent invisible conflicts if the same third-party or primitive types are used as events * Allows for further extensions (e.g. opt-in warning for missed events) ## Solution Remove the blanket impl for the `Event` trait. Add a derive macro for it. --- ## Changelog - `Event` is no longer implemented for all applicable types. Add the `#[derive(Event)]` macro for events. ## Migration Guide * Add the `#[derive(Event)]` macro for events. Third-party types used as events should be wrapped in a newtype.
84 lines
2.5 KiB
Rust
84 lines
2.5 KiB
Rust
//! How to use an external thread to run an infinite task and communicate with a channel.
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use bevy::prelude::*;
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// Using crossbeam_channel instead of std as std `Receiver` is `!Sync`
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use crossbeam_channel::{bounded, Receiver};
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use rand::Rng;
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use std::time::{Duration, Instant};
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fn main() {
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App::new()
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.add_event::<StreamEvent>()
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.add_plugins(DefaultPlugins)
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.add_systems(Startup, setup)
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.add_systems(Update, (read_stream, spawn_text, move_text))
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.run();
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}
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#[derive(Resource, Deref)]
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struct StreamReceiver(Receiver<u32>);
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#[derive(Event)]
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struct StreamEvent(u32);
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fn setup(mut commands: Commands) {
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commands.spawn(Camera2dBundle::default());
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let (tx, rx) = bounded::<u32>(10);
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std::thread::spawn(move || loop {
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// Everything here happens in another thread
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// This is where you could connect to an external data source
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let mut rng = rand::thread_rng();
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let start_time = Instant::now();
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let duration = Duration::from_secs_f32(rng.gen_range(0.0..0.2));
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while start_time.elapsed() < duration {
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// Spinning for 'duration', simulating doing hard work!
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}
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tx.send(rng.gen_range(0..2000)).unwrap();
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});
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commands.insert_resource(StreamReceiver(rx));
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}
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// This system reads from the receiver and sends events to Bevy
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fn read_stream(receiver: Res<StreamReceiver>, mut events: EventWriter<StreamEvent>) {
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for from_stream in receiver.try_iter() {
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events.send(StreamEvent(from_stream));
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}
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}
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fn spawn_text(mut commands: Commands, mut reader: EventReader<StreamEvent>) {
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let text_style = TextStyle {
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font_size: 20.0,
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color: Color::WHITE,
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..default()
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};
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for (per_frame, event) in reader.iter().enumerate() {
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commands.spawn(Text2dBundle {
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text: Text::from_section(event.0.to_string(), text_style.clone())
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.with_alignment(TextAlignment::Center),
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transform: Transform::from_xyz(
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per_frame as f32 * 100.0 + rand::thread_rng().gen_range(-40.0..40.0),
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300.0,
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0.0,
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),
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..default()
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});
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}
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}
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fn move_text(
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mut commands: Commands,
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mut texts: Query<(Entity, &mut Transform), With<Text>>,
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time: Res<Time>,
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) {
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for (entity, mut position) in &mut texts {
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position.translation -= Vec3::new(0.0, 100.0 * time.delta_seconds(), 0.0);
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if position.translation.y < -300.0 {
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commands.entity(entity).despawn();
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}
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}
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}
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