dcc03724a5
# Objective NOTE: This depends on #7267 and should not be merged until #7267 is merged. If you are reviewing this before that is merged, I highly recommend viewing the Base Sets commit instead of trying to find my changes amongst those from #7267. "Default sets" as described by the [Stageless RFC](https://github.com/bevyengine/rfcs/pull/45) have some [unfortunate consequences](https://github.com/bevyengine/bevy/discussions/7365). ## Solution This adds "base sets" as a variant of `SystemSet`: A set is a "base set" if `SystemSet::is_base` returns `true`. Typically this will be opted-in to using the `SystemSet` derive: ```rust #[derive(SystemSet, Clone, Hash, Debug, PartialEq, Eq)] #[system_set(base)] enum MyBaseSet { A, B, } ``` **Base sets are exclusive**: a system can belong to at most one "base set". Adding a system to more than one will result in an error. When possible we fail immediately during system-config-time with a nice file + line number. For the more nested graph-ey cases, this will fail at the final schedule build. **Base sets cannot belong to other sets**: this is where the word "base" comes from Systems and Sets can only be added to base sets using `in_base_set`. Calling `in_set` with a base set will fail. As will calling `in_base_set` with a normal set. ```rust app.add_system(foo.in_base_set(MyBaseSet::A)) // X must be a normal set ... base sets cannot be added to base sets .configure_set(X.in_base_set(MyBaseSet::A)) ``` Base sets can still be configured like normal sets: ```rust app.add_system(MyBaseSet::B.after(MyBaseSet::Ap)) ``` The primary use case for base sets is enabling a "default base set": ```rust schedule.set_default_base_set(CoreSet::Update) // this will belong to CoreSet::Update by default .add_system(foo) // this will override the default base set with PostUpdate .add_system(bar.in_base_set(CoreSet::PostUpdate)) ``` This allows us to build apis that work by default in the standard Bevy style. This is a rough analog to the "default stage" model, but it use the new "stageless sets" model instead, with all of the ordering flexibility (including exclusive systems) that it provides. --- ## Changelog - Added "base sets" and ported CoreSet to use them. ## Migration Guide TODO
47 lines
1.3 KiB
Rust
47 lines
1.3 KiB
Rust
//! Renders a 2D scene containing a single, moving sprite.
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use bevy::prelude::*;
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins)
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.add_startup_system(setup)
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.add_system(sprite_movement)
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.run();
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}
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#[derive(Component)]
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enum Direction {
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Up,
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Down,
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}
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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commands.spawn(Camera2dBundle::default());
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commands.spawn((
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SpriteBundle {
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texture: asset_server.load("branding/icon.png"),
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transform: Transform::from_xyz(100., 0., 0.),
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..default()
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},
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Direction::Up,
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));
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}
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/// The sprite is animated by changing its translation depending on the time that has passed since
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/// the last frame.
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fn sprite_movement(time: Res<Time>, mut sprite_position: Query<(&mut Direction, &mut Transform)>) {
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for (mut logo, mut transform) in &mut sprite_position {
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match *logo {
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Direction::Up => transform.translation.y += 150. * time.delta_seconds(),
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Direction::Down => transform.translation.y -= 150. * time.delta_seconds(),
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}
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if transform.translation.y > 200. {
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*logo = Direction::Down;
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} else if transform.translation.y < -200. {
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*logo = Direction::Up;
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}
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}
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}
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