fcfb685821
# Objective - I got tired of calling `enable_state_scoped_entities`, and though it would make more sense to define that at the place where the state is defined ## Solution - add a derive attribute `#[states(scoped_entities)]` when derive `States` or `SubStates` that enables it automatically when adding the state ## Testing - Ran the examples using it, they still work
93 lines
3.0 KiB
Rust
93 lines
3.0 KiB
Rust
#[cfg(feature = "bevy_reflect")]
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use bevy_ecs::reflect::ReflectComponent;
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use bevy_ecs::{
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component::Component,
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entity::Entity,
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event::EventReader,
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system::{Commands, Query},
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};
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#[cfg(feature = "bevy_hierarchy")]
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use bevy_hierarchy::DespawnRecursiveExt;
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#[cfg(feature = "bevy_reflect")]
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use bevy_reflect::prelude::*;
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use crate::state::{StateTransitionEvent, States};
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/// Entities marked with this component will be removed
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/// when the world's state of the matching type no longer matches the supplied value.
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///
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/// To enable this feature remember to add the attribute `#[states(scoped_entities)]` when deriving [`States`].
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/// It's also possible to enable it when adding the state to an app with [`enable_state_scoped_entities`](crate::app::AppExtStates::enable_state_scoped_entities).
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///
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/// If `bevy_hierarchy` feature is enabled, which it is by default, the despawn will be recursive.
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///
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/// ```
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/// use bevy_state::prelude::*;
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/// use bevy_ecs::prelude::*;
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///
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/// #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, Default, States)]
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/// #[states(scoped_entities)]
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/// enum GameState {
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/// #[default]
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/// MainMenu,
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/// SettingsMenu,
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/// InGame,
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/// }
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///
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/// # #[derive(Component)]
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/// # struct Player;
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///
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/// fn spawn_player(mut commands: Commands) {
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/// commands.spawn((
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/// StateScoped(GameState::InGame),
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/// Player
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/// ));
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/// }
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///
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/// # struct AppMock;
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/// # impl AppMock {
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/// # fn init_state<S>(&mut self) {}
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/// # fn enable_state_scoped_entities<S>(&mut self) {}
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/// # fn add_systems<S, M>(&mut self, schedule: S, systems: impl IntoSystemConfigs<M>) {}
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/// # }
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/// # struct Update;
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/// # let mut app = AppMock;
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///
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/// app.init_state::<GameState>();
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/// app.add_systems(OnEnter(GameState::InGame), spawn_player);
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/// ```
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#[derive(Component, Clone)]
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#[cfg_attr(feature = "bevy_reflect", derive(Reflect), reflect(Component))]
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pub struct StateScoped<S: States>(pub S);
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/// Removes entities marked with [`StateScoped<S>`]
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/// when their state no longer matches the world state.
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///
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/// If `bevy_hierarchy` feature is enabled, which it is by default, the despawn will be recursive.
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pub fn clear_state_scoped_entities<S: States>(
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mut commands: Commands,
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mut transitions: EventReader<StateTransitionEvent<S>>,
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query: Query<(Entity, &StateScoped<S>)>,
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) {
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// We use the latest event, because state machine internals generate at most 1
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// transition event (per type) each frame. No event means no change happened
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// and we skip iterating all entities.
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let Some(transition) = transitions.read().last() else {
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return;
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};
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if transition.entered == transition.exited {
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return;
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}
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let Some(exited) = &transition.exited else {
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return;
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};
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for (entity, binding) in &query {
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if binding.0 == *exited {
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#[cfg(feature = "bevy_hierarchy")]
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commands.entity(entity).despawn_recursive();
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#[cfg(not(feature = "bevy_hierarchy"))]
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commands.entity(entity).despawn();
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}
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}
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}
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