//! How to use an external thread to run an infinite task and communicate with a channel. use bevy::prelude::*; // Using crossbeam_channel instead of std as std `Receiver` is `!Sync` use crossbeam_channel::{bounded, Receiver}; use rand::{rngs::StdRng, Rng, SeedableRng}; use std::time::{Duration, Instant}; fn main() { App::new() .add_event::() .add_plugins(DefaultPlugins) .add_systems(Startup, setup) .add_systems(Update, (read_stream, spawn_text, move_text)) .run(); } #[derive(Resource, Deref)] struct StreamReceiver(Receiver); #[derive(Event)] struct StreamEvent(u32); fn setup(mut commands: Commands) { commands.spawn(Camera2dBundle::default()); let (tx, rx) = bounded::(10); std::thread::spawn(move || { let mut rng = StdRng::seed_from_u64(19878367467713); loop { // Everything here happens in another thread // This is where you could connect to an external data source let start_time = Instant::now(); let duration = Duration::from_secs_f32(rng.gen_range(0.0..0.2)); while start_time.elapsed() < duration { // Spinning for 'duration', simulating doing hard work! } tx.send(rng.gen_range(0..2000)).unwrap(); } }); commands.insert_resource(StreamReceiver(rx)); } // This system reads from the receiver and sends events to Bevy fn read_stream(receiver: Res, mut events: EventWriter) { for from_stream in receiver.try_iter() { events.send(StreamEvent(from_stream)); } } fn spawn_text(mut commands: Commands, mut reader: EventReader) { let text_style = TextStyle { font_size: 20.0, color: Color::WHITE, ..default() }; for (per_frame, event) in reader.read().enumerate() { commands.spawn(Text2dBundle { text: Text::from_section(event.0.to_string(), text_style.clone()) .with_justify(JustifyText::Center), transform: Transform::from_xyz(per_frame as f32 * 100.0, 300.0, 0.0), ..default() }); } } fn move_text( mut commands: Commands, mut texts: Query<(Entity, &mut Transform), With>, time: Res