
# 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
106 lines
3.5 KiB
Rust
106 lines
3.5 KiB
Rust
use std::marker::PhantomData;
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use bevy_app::{App, CoreSet, Plugin};
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use bevy_core::Name;
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use bevy_ecs::prelude::*;
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use bevy_log::warn;
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use bevy_utils::{get_short_name, HashSet};
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use crate::Parent;
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/// When enabled, runs [`check_hierarchy_component_has_valid_parent<T>`].
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///
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/// This resource is added by [`ValidParentCheckPlugin<T>`].
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/// It is enabled on debug builds and disabled in release builds by default,
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/// you can update this resource at runtime to change the default behavior.
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#[derive(Resource)]
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pub struct ReportHierarchyIssue<T> {
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/// Whether to run [`check_hierarchy_component_has_valid_parent<T>`].
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pub enabled: bool,
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_comp: PhantomData<fn(T)>,
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}
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impl<T> ReportHierarchyIssue<T> {
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/// Constructs a new object
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pub fn new(enabled: bool) -> Self {
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ReportHierarchyIssue {
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enabled,
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_comp: Default::default(),
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}
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}
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}
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impl<T> PartialEq for ReportHierarchyIssue<T> {
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fn eq(&self, other: &Self) -> bool {
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self.enabled == other.enabled
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}
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}
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impl<T> Default for ReportHierarchyIssue<T> {
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fn default() -> Self {
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Self {
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enabled: cfg!(debug_assertions),
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_comp: PhantomData,
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}
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}
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}
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/// System to print a warning for each `Entity` with a `T` component
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/// which parent hasn't a `T` component.
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///
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/// Hierarchy propagations are top-down, and limited only to entities
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/// with a specific component (such as `ComputedVisibility` and `GlobalTransform`).
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/// This means that entities with one of those component
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/// and a parent without the same component is probably a programming error.
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/// (See B0004 explanation linked in warning message)
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pub fn check_hierarchy_component_has_valid_parent<T: Component>(
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parent_query: Query<
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(Entity, &Parent, Option<&Name>),
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(With<T>, Or<(Changed<Parent>, Added<T>)>),
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>,
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component_query: Query<(), With<T>>,
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mut already_diagnosed: Local<HashSet<Entity>>,
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) {
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for (entity, parent, name) in &parent_query {
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let parent = parent.get();
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if !component_query.contains(parent) && !already_diagnosed.contains(&entity) {
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already_diagnosed.insert(entity);
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warn!(
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"warning[B0004]: {name} with the {ty_name} component has a parent without {ty_name}.\n\
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This will cause inconsistent behaviors! See https://bevyengine.org/learn/errors/#b0004",
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ty_name = get_short_name(std::any::type_name::<T>()),
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name = name.map_or("An entity".to_owned(), |s| format!("The {s} entity")),
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);
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}
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}
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}
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/// Run criteria that only allows running when [`ReportHierarchyIssue<T>`] is enabled.
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pub fn on_hierarchy_reports_enabled<T>(report: Res<ReportHierarchyIssue<T>>) -> bool
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where
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T: Component,
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{
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report.enabled
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}
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/// Print a warning for each `Entity` with a `T` component
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/// whose parent doesn't have a `T` component.
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///
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/// See [`check_hierarchy_component_has_valid_parent`] for details.
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pub struct ValidParentCheckPlugin<T: Component>(PhantomData<fn() -> T>);
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impl<T: Component> Default for ValidParentCheckPlugin<T> {
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fn default() -> Self {
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Self(PhantomData)
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}
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}
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impl<T: Component> Plugin for ValidParentCheckPlugin<T> {
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fn build(&self, app: &mut App) {
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app.init_resource::<ReportHierarchyIssue<T>>().add_system(
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check_hierarchy_component_has_valid_parent::<T>
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.run_if(resource_equals(ReportHierarchyIssue::<T>::new(true)))
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.in_base_set(CoreSet::Last),
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);
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}
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}
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