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
59 lines
1.8 KiB
Rust
59 lines
1.8 KiB
Rust
//! Illustrates how to rotate an object around an axis.
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use bevy::prelude::*;
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use std::f32::consts::TAU;
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// Define a component to designate a rotation speed to an entity.
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#[derive(Component)]
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struct Rotatable {
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speed: f32,
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}
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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(rotate_cube)
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.run();
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}
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fn setup(
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mut commands: Commands,
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mut meshes: ResMut<Assets<Mesh>>,
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mut materials: ResMut<Assets<StandardMaterial>>,
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) {
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// Spawn a cube to rotate.
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commands.spawn((
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PbrBundle {
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mesh: meshes.add(Mesh::from(shape::Cube { size: 1.0 })),
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material: materials.add(Color::WHITE.into()),
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transform: Transform::from_translation(Vec3::ZERO),
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..default()
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},
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Rotatable { speed: 0.3 },
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));
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// Spawn a camera looking at the entities to show what's happening in this example.
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commands.spawn(Camera3dBundle {
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transform: Transform::from_xyz(0.0, 10.0, 20.0).looking_at(Vec3::ZERO, Vec3::Y),
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..default()
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});
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// Add a light source so we can see clearly.
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commands.spawn(PointLightBundle {
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transform: Transform::from_translation(Vec3::ONE * 3.0),
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..default()
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});
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}
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// This system will rotate any entity in the scene with a Rotatable component around its y-axis.
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fn rotate_cube(mut cubes: Query<(&mut Transform, &Rotatable)>, timer: Res<Time>) {
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for (mut transform, cube) in &mut cubes {
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// The speed is first multiplied by TAU which is a full rotation (360deg) in radians,
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// and then multiplied by delta_seconds which is the time that passed last frame.
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// In other words. Speed is equal to the amount of rotations per second.
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transform.rotate_y(cube.speed * TAU * timer.delta_seconds());
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}
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}
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