992681b59b
*This PR description is an edited copy of #5007, written by @alice-i-cecile.* # Objective Follow-up to https://github.com/bevyengine/bevy/pull/2254. The `Resource` trait currently has a blanket implementation for all types that meet its bounds. While ergonomic, this results in several drawbacks: * it is possible to make confusing, silent mistakes such as inserting a function pointer (Foo) rather than a value (Foo::Bar) as a resource * it is challenging to discover if a type is intended to be used as a resource * we cannot later add customization options (see the [RFC](https://github.com/bevyengine/rfcs/blob/main/rfcs/27-derive-component.md) for the equivalent choice for Component). * dependencies can use the same Rust type as a resource in invisibly conflicting ways * raw Rust types used as resources cannot preserve privacy appropriately, as anyone able to access that type can read and write to internal values * we cannot capture a definitive list of possible resources to display to users in an editor ## Notes to reviewers * Review this commit-by-commit; there's effectively no back-tracking and there's a lot of churn in some of these commits. *ira: My commits are not as well organized :')* * I've relaxed the bound on Local to Send + Sync + 'static: I don't think these concerns apply there, so this can keep things simple. Storing e.g. a u32 in a Local is fine, because there's a variable name attached explaining what it does. * I think this is a bad place for the Resource trait to live, but I've left it in place to make reviewing easier. IMO that's best tackled with https://github.com/bevyengine/bevy/issues/4981. ## Changelog `Resource` is no longer automatically implemented for all matching types. Instead, use the new `#[derive(Resource)]` macro. ## Migration Guide Add `#[derive(Resource)]` to all types you are using as a resource. If you are using a third party type as a resource, wrap it in a tuple struct to bypass orphan rules. Consider deriving `Deref` and `DerefMut` to improve ergonomics. `ClearColor` no longer implements `Component`. Using `ClearColor` as a component in 0.8 did nothing. Use the `ClearColorConfig` in the `Camera3d` and `Camera2d` components instead. Co-authored-by: Alice <alice.i.cecile@gmail.com> Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: devil-ira <justthecooldude@gmail.com> Co-authored-by: Carter Anderson <mcanders1@gmail.com>
92 lines
2.8 KiB
Rust
92 lines
2.8 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_startup_system(setup)
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.add_system(read_stream)
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.add_system(spawn_text)
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.add_system(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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struct StreamEvent(u32);
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#[derive(Resource, Deref)]
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struct LoadedFont(Handle<Font>);
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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commands.spawn_bundle(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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commands.insert_resource(LoadedFont(asset_server.load("fonts/FiraSans-Bold.ttf")));
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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: ResMut<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(
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mut commands: Commands,
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mut reader: EventReader<StreamEvent>,
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loaded_font: Res<LoadedFont>,
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) {
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let text_style = TextStyle {
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font: loaded_font.clone(),
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font_size: 20.0,
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color: Color::WHITE,
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};
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for (per_frame, event) in reader.iter().enumerate() {
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commands.spawn_bundle(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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