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https://github.com/bevyengine/bevy
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Add condition_changed and condition_became_true to common_conditions (#14917)
# Objective - I needed to run a system whenever a specific condition became true after being previously false. - Other users might also need to run a system when a condition changes, regardless of if it became true or false. ## Solution - This adds two systems to common_conditions: - `condition_changed` that changes whenever the inner condition changes - `condition_became_true` that returns true whenever the inner condition becomes true after previously being false ## Testing - I added a doctest for each function --------- Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com> Co-authored-by: Jan Hohenheim <jan@hohenheim.ch>
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Alix Bott
GitHub
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23979b8160
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12f005a024
1 changed files with 118 additions and 15 deletions
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@ -490,16 +490,16 @@ mod sealed {
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/// A collection of [run conditions](Condition) that may be useful in any bevy app.
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pub mod common_conditions {
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use super::NotSystem;
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use super::{Condition, NotSystem};
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use crate::{
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change_detection::DetectChanges,
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event::{Event, EventReader},
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prelude::{Component, Query, With},
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removal_detection::RemovedComponents,
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system::{IntoSystem, Local, Res, Resource, System},
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system::{In, IntoSystem, Local, Res, Resource, System},
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};
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// on the first time the condition is run and false every time after.
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///
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/// # Example
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@ -537,7 +537,7 @@ pub mod common_conditions {
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}
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if the resource exists.
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///
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/// # Example
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@ -572,7 +572,7 @@ pub mod common_conditions {
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res.is_some()
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}
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/// Generates a [`Condition`](super::Condition)-satisfying closure that returns `true`
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/// Generates a [`Condition`]-satisfying closure that returns `true`
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/// if the resource is equal to `value`.
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///
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/// # Panics
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@ -612,7 +612,7 @@ pub mod common_conditions {
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move |res: Res<T>| *res == value
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}
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/// Generates a [`Condition`](super::Condition)-satisfying closure that returns `true`
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/// Generates a [`Condition`]-satisfying closure that returns `true`
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/// if the resource exists and is equal to `value`.
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///
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/// The condition will return `false` if the resource does not exist.
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@ -657,7 +657,7 @@ pub mod common_conditions {
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}
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if the resource of the given type has been added since the condition was last checked.
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///
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/// # Example
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@ -698,7 +698,7 @@ pub mod common_conditions {
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}
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if the resource of the given type has had its value changed since the condition
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/// was last checked.
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///
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@ -752,7 +752,7 @@ pub mod common_conditions {
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res.is_changed()
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if the resource of the given type has had its value changed since the condition
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/// was last checked.
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///
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@ -812,7 +812,7 @@ pub mod common_conditions {
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}
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if the resource of the given type has had its value changed since the condition
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/// was last checked.
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///
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@ -889,7 +889,7 @@ pub mod common_conditions {
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}
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if the resource of the given type has been removed since the condition was last checked.
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///
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/// # Example
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@ -941,7 +941,7 @@ pub mod common_conditions {
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}
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if there are any new events of the given type since it was last called.
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///
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/// # Example
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@ -985,7 +985,7 @@ pub mod common_conditions {
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reader.read().count() > 0
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if there are any entities with the given component type.
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///
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/// # Example
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@ -1022,7 +1022,7 @@ pub mod common_conditions {
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!query.is_empty()
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}
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/// A [`Condition`](super::Condition)-satisfying system that returns `true`
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/// A [`Condition`]-satisfying system that returns `true`
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/// if there are any entity with a component of the given type removed.
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pub fn any_component_removed<T: Component>(mut removals: RemovedComponents<T>) -> bool {
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// `RemovedComponents` based on events and therefore events need to be consumed,
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@ -1033,7 +1033,7 @@ pub mod common_conditions {
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removals.read().count() > 0
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}
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/// Generates a [`Condition`](super::Condition) that inverses the result of passed one.
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/// Generates a [`Condition`] that inverses the result of passed one.
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///
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/// # Example
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///
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@ -1071,6 +1071,109 @@ pub mod common_conditions {
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let name = format!("!{}", condition.name());
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NotSystem::new(super::NotMarker, condition, name.into())
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}
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/// Generates a [`Condition`] that returns true when the passed one changes.
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///
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/// The first time this is called, the passed condition is assumed to have been previously false.
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///
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/// # Example
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Resource, Default)]
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/// # struct Counter(u8);
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/// # let mut app = Schedule::default();
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/// # let mut world = World::new();
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/// # world.init_resource::<Counter>();
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/// app.add_systems(
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/// my_system.run_if(condition_changed(resource_exists::<MyResource>)),
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/// );
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///
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/// #[derive(Resource)]
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/// struct MyResource;
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///
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/// fn my_system(mut counter: ResMut<Counter>) {
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/// counter.0 += 1;
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/// }
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///
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/// // `MyResource` is initially there, the inner condition is true, the system runs once
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/// world.insert_resource(MyResource);
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 1);
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 1);
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///
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/// // We remove `MyResource`, the inner condition is now false, the system runs one more time.
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/// world.remove_resource::<MyResource>();
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 2);
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 2);
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/// ```
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pub fn condition_changed<Marker, CIn, C: Condition<Marker, CIn>>(
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condition: C,
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) -> impl Condition<(), CIn> {
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condition.pipe(|In(new): In<bool>, mut prev: Local<bool>| -> bool {
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let changed = *prev != new;
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*prev = new;
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changed
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})
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}
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/// Generates a [`Condition`] that returns true when the result of
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/// the passed one went from false to true since the last time this was called.
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///
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/// The first time this is called, the passed condition is assumed to have been previously false.
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///
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/// # Example
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///
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/// ```
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/// # use bevy_ecs::prelude::*;
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/// # #[derive(Resource, Default)]
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/// # struct Counter(u8);
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/// # let mut app = Schedule::default();
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/// # let mut world = World::new();
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/// # world.init_resource::<Counter>();
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/// app.add_systems(
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/// my_system.run_if(condition_changed_to(true, resource_exists::<MyResource>)),
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/// );
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///
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/// #[derive(Resource)]
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/// struct MyResource;
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///
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/// fn my_system(mut counter: ResMut<Counter>) {
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/// counter.0 += 1;
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/// }
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///
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/// // `MyResource` is initially there, the inner condition is true, the system runs once
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/// world.insert_resource(MyResource);
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 1);
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 1);
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///
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/// // We remove `MyResource`, the inner condition is now false, the system doesn't run.
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/// world.remove_resource::<MyResource>();
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 1);
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///
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/// // We reinsert `MyResource` again, so the system will run one more time
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/// world.insert_resource(MyResource);
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 2);
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/// app.run(&mut world);
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/// assert_eq!(world.resource::<Counter>().0, 2);
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/// ```
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pub fn condition_changed_to<Marker, CIn, C: Condition<Marker, CIn>>(
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to: bool,
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condition: C,
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) -> impl Condition<(), CIn> {
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condition.pipe(move |In(new): In<bool>, mut prev: Local<bool>| -> bool {
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let now_true = *prev != new && new == to;
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*prev = new;
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now_true
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})
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}
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}
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/// Invokes [`Not`] with the output of another system.
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