6f7d0e5725
# Objective
Currently text is recomputed unnecessarily on any changes to its color,
which is extremely expensive.
## Solution
Split up `TextStyle` into two separate components `TextFont` and
`TextColor`.
## Testing
I added this system to `many_buttons`:
```rust
fn set_text_colors_changed(mut colors: Query<&mut TextColor>) {
for mut text_color in colors.iter_mut() {
text_color.set_changed();
}
}
```
reports ~4fps on main, ~50fps with this PR.
## Migration Guide
`TextStyle` has been renamed to `TextFont` and its `color` field has
been moved to a separate component named `TextColor` which newtypes
`Color`.
78 lines
2.5 KiB
Rust
78 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, SeedableRng};
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use rand_chacha::ChaCha8Rng;
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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(Camera2d);
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let (tx, rx) = bounded::<u32>(10);
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std::thread::spawn(move || {
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// We're seeding the PRNG here to make this example deterministic for testing purposes.
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// This isn't strictly required in practical use unless you need your app to be deterministic.
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let mut rng = ChaCha8Rng::seed_from_u64(19878367467713);
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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 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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});
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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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for (per_frame, event) in reader.read().enumerate() {
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commands.spawn((
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Text2d::new(event.0.to_string()),
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TextLayout::new_with_justify(JustifyText::Center),
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Transform::from_xyz(per_frame as f32 * 100.0, 300.0, 0.0),
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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<Text2d>>,
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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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