# 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
		
			
				
	
	
		
			121 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
			
		
		
	
	
			121 lines
		
	
	
		
			3.7 KiB
		
	
	
	
		
			Rust
		
	
	
	
	
	
//! Renders two cameras to the same window to accomplish "split screen".
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use std::f32::consts::PI;
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use bevy::{
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    core_pipeline::clear_color::ClearColorConfig, pbr::CascadeShadowConfigBuilder, prelude::*,
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    render::camera::Viewport, window::WindowResized,
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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(set_camera_viewports)
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        .run();
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}
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/// set up a simple 3D scene
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fn setup(
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    mut commands: Commands,
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    asset_server: Res<AssetServer>,
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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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    // plane
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    commands.spawn(PbrBundle {
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        mesh: meshes.add(Mesh::from(shape::Plane { size: 100.0 })),
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        material: materials.add(Color::rgb(0.3, 0.5, 0.3).into()),
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        ..default()
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    });
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    commands.spawn(SceneBundle {
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        scene: asset_server.load("models/animated/Fox.glb#Scene0"),
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        ..default()
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    });
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    // Light
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    commands.spawn(DirectionalLightBundle {
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        transform: Transform::from_rotation(Quat::from_euler(EulerRot::ZYX, 0.0, 1.0, -PI / 4.)),
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        directional_light: DirectionalLight {
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            shadows_enabled: true,
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            ..default()
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        },
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        cascade_shadow_config: CascadeShadowConfigBuilder {
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            num_cascades: 2,
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            first_cascade_far_bound: 200.0,
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            maximum_distance: 280.0,
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            ..default()
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        }
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        .into(),
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        ..default()
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    });
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    // Left Camera
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    commands.spawn((
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        Camera3dBundle {
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            transform: Transform::from_xyz(0.0, 200.0, -100.0).looking_at(Vec3::ZERO, Vec3::Y),
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            ..default()
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        },
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        LeftCamera,
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    ));
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    // Right Camera
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    commands.spawn((
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        Camera3dBundle {
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            transform: Transform::from_xyz(100.0, 100., 150.0).looking_at(Vec3::ZERO, Vec3::Y),
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            camera: Camera {
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                // Renders the right camera after the left camera, which has a default priority of 0
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                order: 1,
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                ..default()
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            },
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            camera_3d: Camera3d {
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                // don't clear on the second camera because the first camera already cleared the window
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                clear_color: ClearColorConfig::None,
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                ..default()
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            },
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            ..default()
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        },
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        RightCamera,
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    ));
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}
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#[derive(Component)]
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struct LeftCamera;
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#[derive(Component)]
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struct RightCamera;
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fn set_camera_viewports(
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    windows: Query<&Window>,
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    mut resize_events: EventReader<WindowResized>,
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    mut left_camera: Query<&mut Camera, (With<LeftCamera>, Without<RightCamera>)>,
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    mut right_camera: Query<&mut Camera, With<RightCamera>>,
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) {
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    // We need to dynamically resize the camera's viewports whenever the window size changes
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    // so then each camera always takes up half the screen.
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    // A resize_event is sent when the window is first created, allowing us to reuse this system for initial setup.
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    for resize_event in resize_events.iter() {
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        let window = windows.get(resize_event.window).unwrap();
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        let mut left_camera = left_camera.single_mut();
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        left_camera.viewport = Some(Viewport {
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            physical_position: UVec2::new(0, 0),
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            physical_size: UVec2::new(
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                window.resolution.physical_width() / 2,
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                window.resolution.physical_height(),
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            ),
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            ..default()
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        });
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        let mut right_camera = right_camera.single_mut();
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        right_camera.viewport = Some(Viewport {
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            physical_position: UVec2::new(window.resolution.physical_width() / 2, 0),
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            physical_size: UVec2::new(
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                window.resolution.physical_width() / 2,
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                window.resolution.physical_height(),
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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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