f07bb3c449
# Objective EntityRef::get_change_ticks mentions that ComponentTicks is useful to create change detection for your own runtime. However, ComponentTicks doesn't even expose enough data to create something that implements DetectChanges. Specifically, we need to be able to extract the last change tick. ## Solution We add a method to get the last change tick. We also add a method to get the added tick. ## Changelog - Add `last_changed_tick` and `added_tick` to `ComponentTicks`
842 lines
28 KiB
Rust
842 lines
28 KiB
Rust
//! Types for declaring and storing [`Component`]s.
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use crate::{
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change_detection::MAX_CHANGE_AGE,
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storage::{SparseSetIndex, Storages},
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system::{Local, Resource},
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world::{FromWorld, World},
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TypeIdMap,
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};
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pub use bevy_ecs_macros::Component;
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use bevy_ptr::{OwningPtr, UnsafeCellDeref};
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use std::cell::UnsafeCell;
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use std::{
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alloc::Layout,
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any::{Any, TypeId},
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borrow::Cow,
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marker::PhantomData,
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mem::needs_drop,
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};
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/// A data type that can be used to store data for an [entity].
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///
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/// `Component` is a [derivable trait]: this means that a data type can implement it by applying a `#[derive(Component)]` attribute to it.
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/// However, components must always satisfy the `Send + Sync + 'static` trait bounds.
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///
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/// [entity]: crate::entity
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/// [derivable trait]: https://doc.rust-lang.org/book/appendix-03-derivable-traits.html
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///
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/// # Examples
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///
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/// Components can take many forms: they are usually structs, but can also be of every other kind of data type, like enums or zero sized types.
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/// The following examples show how components are laid out in code.
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///
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/// ```
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/// # use bevy_ecs::component::Component;
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/// # struct Color;
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/// #
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/// // A component can contain data...
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/// #[derive(Component)]
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/// struct LicensePlate(String);
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///
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/// // ... but it can also be a zero-sized marker.
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/// #[derive(Component)]
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/// struct Car;
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///
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/// // Components can also be structs with named fields...
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/// #[derive(Component)]
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/// struct VehiclePerformance {
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/// acceleration: f32,
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/// top_speed: f32,
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/// handling: f32,
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/// }
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///
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/// // ... or enums.
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/// #[derive(Component)]
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/// enum WheelCount {
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/// Two,
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/// Three,
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/// Four,
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/// }
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/// ```
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///
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/// # Component and data access
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///
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/// See the [`entity`] module level documentation to learn how to add or remove components from an entity.
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///
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/// See the documentation for [`Query`] to learn how to access component data from a system.
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///
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/// [`entity`]: crate::entity#usage
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/// [`Query`]: crate::system::Query
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///
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/// # Choosing a storage type
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///
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/// Components can be stored in the world using different strategies with their own performance implications.
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/// By default, components are added to the [`Table`] storage, which is optimized for query iteration.
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///
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/// Alternatively, components can be added to the [`SparseSet`] storage, which is optimized for component insertion and removal.
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/// This is achieved by adding an additional `#[component(storage = "SparseSet")]` attribute to the derive one:
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///
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/// ```
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/// # use bevy_ecs::component::Component;
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/// #
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/// #[derive(Component)]
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/// #[component(storage = "SparseSet")]
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/// struct ComponentA;
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/// ```
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///
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/// [`Table`]: crate::storage::Table
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/// [`SparseSet`]: crate::storage::SparseSet
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///
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/// # Implementing the trait for foreign types
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///
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/// As a consequence of the [orphan rule], it is not possible to separate into two different crates the implementation of `Component` from the definition of a type.
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/// This means that it is not possible to directly have a type defined in a third party library as a component.
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/// This important limitation can be easily worked around using the [newtype pattern]:
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/// this makes it possible to locally define and implement `Component` for a tuple struct that wraps the foreign type.
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/// The following example gives a demonstration of this pattern.
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///
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/// ```
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/// // `Component` is defined in the `bevy_ecs` crate.
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/// use bevy_ecs::component::Component;
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///
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/// // `Duration` is defined in the `std` crate.
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/// use std::time::Duration;
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///
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/// // It is not possible to implement `Component` for `Duration` from this position, as they are
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/// // both foreign items, defined in an external crate. However, nothing prevents to define a new
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/// // `Cooldown` type that wraps `Duration`. As `Cooldown` is defined in a local crate, it is
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/// // possible to implement `Component` for it.
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/// #[derive(Component)]
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/// struct Cooldown(Duration);
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/// ```
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///
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/// [orphan rule]: https://doc.rust-lang.org/book/ch10-02-traits.html#implementing-a-trait-on-a-type
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/// [newtype pattern]: https://doc.rust-lang.org/book/ch19-03-advanced-traits.html#using-the-newtype-pattern-to-implement-external-traits-on-external-types
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///
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/// # `!Sync` Components
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/// A `!Sync` type cannot implement `Component`. However, it is possible to wrap a `Send` but not `Sync`
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/// type in [`SyncCell`] or the currently unstable [`Exclusive`] to make it `Sync`. This forces only
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/// having mutable access (`&mut T` only, never `&T`), but makes it safe to reference across multiple
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/// threads.
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///
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/// This will fail to compile since `RefCell` is `!Sync`.
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/// ```compile_fail
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/// # use std::cell::RefCell;
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/// # use bevy_ecs::component::Component;
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/// #[derive(Component)]
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/// struct NotSync {
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/// counter: RefCell<usize>,
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/// }
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/// ```
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///
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/// This will compile since the `RefCell` is wrapped with `SyncCell`.
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/// ```
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/// # use std::cell::RefCell;
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/// # use bevy_ecs::component::Component;
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/// use bevy_utils::synccell::SyncCell;
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///
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/// // This will compile.
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/// #[derive(Component)]
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/// struct ActuallySync {
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/// counter: SyncCell<RefCell<usize>>,
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/// }
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/// ```
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///
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/// [`SyncCell`]: bevy_utils::synccell::SyncCell
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/// [`Exclusive`]: https://doc.rust-lang.org/nightly/std/sync/struct.Exclusive.html
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pub trait Component: Send + Sync + 'static {
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/// A marker type indicating the storage type used for this component.
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/// This must be either [`TableStorage`] or [`SparseStorage`].
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type Storage: ComponentStorage;
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}
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/// Marker type for components stored in a [`Table`](crate::storage::Table).
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pub struct TableStorage;
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/// Marker type for components stored in a [`ComponentSparseSet`](crate::storage::ComponentSparseSet).
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pub struct SparseStorage;
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/// Types used to specify the storage strategy for a component.
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///
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/// This trait is implemented for [`TableStorage`] and [`SparseStorage`].
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/// Custom implementations are forbidden.
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pub trait ComponentStorage: sealed::Sealed {
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/// A value indicating the storage strategy specified by this type.
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const STORAGE_TYPE: StorageType;
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}
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impl ComponentStorage for TableStorage {
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const STORAGE_TYPE: StorageType = StorageType::Table;
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}
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impl ComponentStorage for SparseStorage {
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const STORAGE_TYPE: StorageType = StorageType::SparseSet;
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}
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mod sealed {
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pub trait Sealed {}
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impl Sealed for super::TableStorage {}
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impl Sealed for super::SparseStorage {}
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}
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/// The storage used for a specific component type.
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///
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/// # Examples
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/// The [`StorageType`] for a component is configured via the derive attribute
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///
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/// ```
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/// # use bevy_ecs::{prelude::*, component::*};
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/// #[derive(Component)]
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/// #[component(storage = "SparseSet")]
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/// struct A;
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/// ```
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#[derive(Debug, Copy, Clone, Default, Eq, PartialEq)]
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pub enum StorageType {
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/// Provides fast and cache-friendly iteration, but slower addition and removal of components.
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/// This is the default storage type.
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#[default]
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Table,
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/// Provides fast addition and removal of components, but slower iteration.
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SparseSet,
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}
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/// Stores metadata for a type of component or resource stored in a specific [`World`].
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#[derive(Debug)]
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pub struct ComponentInfo {
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id: ComponentId,
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descriptor: ComponentDescriptor,
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}
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impl ComponentInfo {
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/// Returns a value uniquely identifying the current component.
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#[inline]
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pub fn id(&self) -> ComponentId {
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self.id
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}
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/// Returns the name of the current component.
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#[inline]
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pub fn name(&self) -> &str {
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&self.descriptor.name
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}
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/// Returns the [`TypeId`] of the underlying component type.
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/// Returns `None` if the component does not correspond to a Rust type.
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#[inline]
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pub fn type_id(&self) -> Option<TypeId> {
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self.descriptor.type_id
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}
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/// Returns the layout used to store values of this component in memory.
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#[inline]
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pub fn layout(&self) -> Layout {
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self.descriptor.layout
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}
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#[inline]
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/// Get the function which should be called to clean up values of
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/// the underlying component type. This maps to the
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/// [`Drop`] implementation for 'normal' Rust components
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///
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/// Returns `None` if values of the underlying component type don't
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/// need to be dropped, e.g. as reported by [`needs_drop`].
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pub fn drop(&self) -> Option<unsafe fn(OwningPtr<'_>)> {
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self.descriptor.drop
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}
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/// Returns a value indicating the storage strategy for the current component.
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#[inline]
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pub fn storage_type(&self) -> StorageType {
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self.descriptor.storage_type
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}
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/// Returns `true` if the underlying component type can be freely shared between threads.
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/// If this returns `false`, then extra care must be taken to ensure that components
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/// are not accessed from the wrong thread.
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#[inline]
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pub fn is_send_and_sync(&self) -> bool {
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self.descriptor.is_send_and_sync
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}
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/// Create a new [`ComponentInfo`].
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pub(crate) fn new(id: ComponentId, descriptor: ComponentDescriptor) -> Self {
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ComponentInfo { id, descriptor }
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}
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}
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/// A value which uniquely identifies the type of a [`Component`] within a
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/// [`World`](crate::world::World).
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///
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/// Each time a new `Component` type is registered within a `World` using
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/// [`World::init_component`](crate::world::World::init_component) or
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/// [`World::init_component_with_descriptor`](crate::world::World::init_component_with_descriptor),
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/// a corresponding `ComponentId` is created to track it.
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///
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/// While the distinction between `ComponentId` and [`TypeId`] may seem superficial, breaking them
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/// into two separate but related concepts allows components to exist outside of Rust's type system.
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/// Each Rust type registered as a `Component` will have a corresponding `ComponentId`, but additional
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/// `ComponentId`s may exist in a `World` to track components which cannot be
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/// represented as Rust types for scripting or other advanced use-cases.
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///
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/// A `ComponentId` is tightly coupled to its parent `World`. Attempting to use a `ComponentId` from
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/// one `World` to access the metadata of a `Component` in a different `World` is undefined behavior
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/// and must not be attempted.
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#[derive(Debug, Copy, Clone, Hash, Ord, PartialOrd, Eq, PartialEq)]
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pub struct ComponentId(usize);
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impl ComponentId {
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/// Creates a new [`ComponentId`].
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///
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/// The `index` is a unique value associated with each type of component in a given world.
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/// Usually, this value is taken from a counter incremented for each type of component registered with the world.
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#[inline]
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pub const fn new(index: usize) -> ComponentId {
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ComponentId(index)
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}
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/// Returns the index of the current component.
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#[inline]
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pub fn index(self) -> usize {
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self.0
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}
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}
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impl SparseSetIndex for ComponentId {
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#[inline]
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fn sparse_set_index(&self) -> usize {
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self.index()
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}
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#[inline]
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fn get_sparse_set_index(value: usize) -> Self {
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Self(value)
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}
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}
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/// A value describing a component or resource, which may or may not correspond to a Rust type.
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pub struct ComponentDescriptor {
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name: Cow<'static, str>,
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// SAFETY: This must remain private. It must match the statically known StorageType of the
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// associated rust component type if one exists.
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storage_type: StorageType,
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// SAFETY: This must remain private. It must only be set to "true" if this component is
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// actually Send + Sync
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is_send_and_sync: bool,
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type_id: Option<TypeId>,
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layout: Layout,
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// SAFETY: this function must be safe to call with pointers pointing to items of the type
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// this descriptor describes.
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// None if the underlying type doesn't need to be dropped
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drop: Option<for<'a> unsafe fn(OwningPtr<'a>)>,
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}
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// We need to ignore the `drop` field in our `Debug` impl
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impl std::fmt::Debug for ComponentDescriptor {
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fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
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f.debug_struct("ComponentDescriptor")
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.field("name", &self.name)
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.field("storage_type", &self.storage_type)
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.field("is_send_and_sync", &self.is_send_and_sync)
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.field("type_id", &self.type_id)
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.field("layout", &self.layout)
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.finish()
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}
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}
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impl ComponentDescriptor {
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// SAFETY: The pointer points to a valid value of type `T` and it is safe to drop this value.
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unsafe fn drop_ptr<T>(x: OwningPtr<'_>) {
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x.drop_as::<T>();
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}
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/// Create a new `ComponentDescriptor` for the type `T`.
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pub fn new<T: Component>() -> Self {
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Self {
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name: Cow::Borrowed(std::any::type_name::<T>()),
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storage_type: T::Storage::STORAGE_TYPE,
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is_send_and_sync: true,
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type_id: Some(TypeId::of::<T>()),
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layout: Layout::new::<T>(),
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drop: needs_drop::<T>().then_some(Self::drop_ptr::<T> as _),
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}
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}
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/// Create a new `ComponentDescriptor`.
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///
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/// # Safety
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/// - the `drop` fn must be usable on a pointer with a value of the layout `layout`
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/// - the component type must be safe to access from any thread (Send + Sync in rust terms)
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pub unsafe fn new_with_layout(
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name: impl Into<Cow<'static, str>>,
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storage_type: StorageType,
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layout: Layout,
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drop: Option<for<'a> unsafe fn(OwningPtr<'a>)>,
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) -> Self {
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Self {
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name: name.into(),
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storage_type,
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is_send_and_sync: true,
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type_id: None,
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layout,
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drop,
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}
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}
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/// Create a new `ComponentDescriptor` for a resource.
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///
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/// The [`StorageType`] for resources is always [`TableStorage`].
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pub fn new_resource<T: Resource>() -> Self {
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Self {
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name: Cow::Borrowed(std::any::type_name::<T>()),
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// PERF: `SparseStorage` may actually be a more
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// reasonable choice as `storage_type` for resources.
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storage_type: StorageType::Table,
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is_send_and_sync: true,
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type_id: Some(TypeId::of::<T>()),
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layout: Layout::new::<T>(),
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drop: needs_drop::<T>().then_some(Self::drop_ptr::<T> as _),
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}
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}
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fn new_non_send<T: Any>(storage_type: StorageType) -> Self {
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Self {
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name: Cow::Borrowed(std::any::type_name::<T>()),
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storage_type,
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is_send_and_sync: false,
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type_id: Some(TypeId::of::<T>()),
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layout: Layout::new::<T>(),
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drop: needs_drop::<T>().then_some(Self::drop_ptr::<T> as _),
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}
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}
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/// Returns a value indicating the storage strategy for the current component.
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#[inline]
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pub fn storage_type(&self) -> StorageType {
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self.storage_type
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}
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/// Returns the [`TypeId`] of the underlying component type.
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/// Returns `None` if the component does not correspond to a Rust type.
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#[inline]
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pub fn type_id(&self) -> Option<TypeId> {
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self.type_id
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}
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/// Returns the name of the current component.
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#[inline]
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pub fn name(&self) -> &str {
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self.name.as_ref()
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}
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}
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/// Stores metadata associated with each kind of [`Component`] in a given [`World`].
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#[derive(Debug, Default)]
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pub struct Components {
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components: Vec<ComponentInfo>,
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indices: TypeIdMap<usize>,
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resource_indices: TypeIdMap<usize>,
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}
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impl Components {
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/// Initializes a component of type `T` with this instance.
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/// If a component of this type has already been initialized, this will return
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/// the ID of the pre-existing component.
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#[inline]
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pub fn init_component<T: Component>(&mut self, storages: &mut Storages) -> ComponentId {
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let type_id = TypeId::of::<T>();
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let Components {
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indices,
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components,
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..
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} = self;
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let index = indices.entry(type_id).or_insert_with(|| {
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Components::init_component_inner(components, storages, ComponentDescriptor::new::<T>())
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});
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ComponentId(*index)
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}
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/// Initializes a component described by `descriptor`.
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///
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/// ## Note
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///
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/// If this method is called multiple times with identical descriptors, a distinct `ComponentId`
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/// will be created for each one.
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pub fn init_component_with_descriptor(
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&mut self,
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storages: &mut Storages,
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descriptor: ComponentDescriptor,
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) -> ComponentId {
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let index = Components::init_component_inner(&mut self.components, storages, descriptor);
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ComponentId(index)
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}
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#[inline]
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fn init_component_inner(
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components: &mut Vec<ComponentInfo>,
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storages: &mut Storages,
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descriptor: ComponentDescriptor,
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) -> usize {
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let index = components.len();
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let info = ComponentInfo::new(ComponentId(index), descriptor);
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if info.descriptor.storage_type == StorageType::SparseSet {
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storages.sparse_sets.get_or_insert(&info);
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}
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components.push(info);
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index
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}
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/// Returns the number of components registered with this instance.
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#[inline]
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pub fn len(&self) -> usize {
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self.components.len()
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|
}
|
|
|
|
/// Returns `true` if there are no components registered with this instance. Otherwise, this returns `false`.
|
|
#[inline]
|
|
pub fn is_empty(&self) -> bool {
|
|
self.components.len() == 0
|
|
}
|
|
|
|
/// Gets the metadata associated with the given component.
|
|
///
|
|
/// This will return an incorrect result if `id` did not come from the same world as `self`. It may return `None` or a garbage value.
|
|
#[inline]
|
|
pub fn get_info(&self, id: ComponentId) -> Option<&ComponentInfo> {
|
|
self.components.get(id.0)
|
|
}
|
|
|
|
/// Returns the name associated with the given component.
|
|
///
|
|
/// This will return an incorrect result if `id` did not come from the same world as `self`. It may return `None` or a garbage value.
|
|
#[inline]
|
|
pub fn get_name(&self, id: ComponentId) -> Option<&str> {
|
|
self.get_info(id).map(|descriptor| descriptor.name())
|
|
}
|
|
|
|
/// Gets the metadata associated with the given component.
|
|
/// # Safety
|
|
///
|
|
/// `id` must be a valid [`ComponentId`]
|
|
#[inline]
|
|
pub unsafe fn get_info_unchecked(&self, id: ComponentId) -> &ComponentInfo {
|
|
debug_assert!(id.index() < self.components.len());
|
|
self.components.get_unchecked(id.0)
|
|
}
|
|
|
|
/// Type-erased equivalent of [`Components::component_id`].
|
|
#[inline]
|
|
pub fn get_id(&self, type_id: TypeId) -> Option<ComponentId> {
|
|
self.indices.get(&type_id).map(|index| ComponentId(*index))
|
|
}
|
|
|
|
/// Returns the [`ComponentId`] of the given [`Component`] type `T`.
|
|
///
|
|
/// The returned `ComponentId` is specific to the `Components` instance
|
|
/// it was retrieved from and should not be used with another `Components`
|
|
/// instance.
|
|
///
|
|
/// Returns [`None`] if the `Component` type has not
|
|
/// yet been initialized using [`Components::init_component`].
|
|
///
|
|
/// ```rust
|
|
/// use bevy_ecs::prelude::*;
|
|
///
|
|
/// let mut world = World::new();
|
|
///
|
|
/// #[derive(Component)]
|
|
/// struct ComponentA;
|
|
///
|
|
/// let component_a_id = world.init_component::<ComponentA>();
|
|
///
|
|
/// assert_eq!(component_a_id, world.components().component_id::<ComponentA>().unwrap())
|
|
/// ```
|
|
#[inline]
|
|
pub fn component_id<T: Component>(&self) -> Option<ComponentId> {
|
|
self.get_id(TypeId::of::<T>())
|
|
}
|
|
|
|
/// Type-erased equivalent of [`Components::resource_id`].
|
|
#[inline]
|
|
pub fn get_resource_id(&self, type_id: TypeId) -> Option<ComponentId> {
|
|
self.resource_indices
|
|
.get(&type_id)
|
|
.map(|index| ComponentId(*index))
|
|
}
|
|
|
|
/// Returns the [`ComponentId`] of the given [`Resource`] type `T`.
|
|
///
|
|
/// The returned `ComponentId` is specific to the `Components` instance
|
|
/// it was retrieved from and should not be used with another `Components`
|
|
/// instance.
|
|
///
|
|
/// Returns [`None`] if the `Resource` type has not
|
|
/// yet been initialized using [`Components::init_resource`].
|
|
///
|
|
/// ```rust
|
|
/// use bevy_ecs::prelude::*;
|
|
///
|
|
/// let mut world = World::new();
|
|
///
|
|
/// #[derive(Resource, Default)]
|
|
/// struct ResourceA;
|
|
///
|
|
/// let resource_a_id = world.init_resource::<ResourceA>();
|
|
///
|
|
/// assert_eq!(resource_a_id, world.components().resource_id::<ResourceA>().unwrap())
|
|
/// ```
|
|
#[inline]
|
|
pub fn resource_id<T: Resource>(&self) -> Option<ComponentId> {
|
|
self.get_resource_id(TypeId::of::<T>())
|
|
}
|
|
|
|
/// Initializes a [`Resource`] of type `T` with this instance.
|
|
/// If a resource of this type has already been initialized, this will return
|
|
/// the ID of the pre-existing resource.
|
|
#[inline]
|
|
pub fn init_resource<T: Resource>(&mut self) -> ComponentId {
|
|
// SAFETY: The [`ComponentDescriptor`] matches the [`TypeId`]
|
|
unsafe {
|
|
self.get_or_insert_resource_with(TypeId::of::<T>(), || {
|
|
ComponentDescriptor::new_resource::<T>()
|
|
})
|
|
}
|
|
}
|
|
|
|
/// Initializes a [non-send resource](crate::system::NonSend) of type `T` with this instance.
|
|
/// If a resource of this type has already been initialized, this will return
|
|
/// the ID of the pre-existing resource.
|
|
#[inline]
|
|
pub fn init_non_send<T: Any>(&mut self) -> ComponentId {
|
|
// SAFETY: The [`ComponentDescriptor`] matches the [`TypeId`]
|
|
unsafe {
|
|
self.get_or_insert_resource_with(TypeId::of::<T>(), || {
|
|
ComponentDescriptor::new_non_send::<T>(StorageType::default())
|
|
})
|
|
}
|
|
}
|
|
|
|
/// # Safety
|
|
///
|
|
/// The [`ComponentDescriptor`] must match the [`TypeId`]
|
|
#[inline]
|
|
unsafe fn get_or_insert_resource_with(
|
|
&mut self,
|
|
type_id: TypeId,
|
|
func: impl FnOnce() -> ComponentDescriptor,
|
|
) -> ComponentId {
|
|
let components = &mut self.components;
|
|
let index = self.resource_indices.entry(type_id).or_insert_with(|| {
|
|
let descriptor = func();
|
|
let index = components.len();
|
|
components.push(ComponentInfo::new(ComponentId(index), descriptor));
|
|
index
|
|
});
|
|
|
|
ComponentId(*index)
|
|
}
|
|
|
|
/// Gets an iterator over all components registered with this instance.
|
|
pub fn iter(&self) -> impl Iterator<Item = &ComponentInfo> + '_ {
|
|
self.components.iter()
|
|
}
|
|
}
|
|
|
|
/// A value that tracks when a system ran relative to other systems.
|
|
/// This is used to power change detection.
|
|
#[derive(Copy, Clone, Debug)]
|
|
pub struct Tick {
|
|
tick: u32,
|
|
}
|
|
|
|
impl Tick {
|
|
/// The maximum relative age for a change tick.
|
|
/// The value of this is equal to [`crate::change_detection::MAX_CHANGE_AGE`].
|
|
///
|
|
/// Since change detection will not work for any ticks older than this,
|
|
/// ticks are periodically scanned to ensure their relative values are below this.
|
|
pub const MAX: Self = Self::new(MAX_CHANGE_AGE);
|
|
|
|
/// Creates a new [`Tick`] wrapping the given value.
|
|
#[inline]
|
|
pub const fn new(tick: u32) -> Self {
|
|
Self { tick }
|
|
}
|
|
|
|
/// Gets the value of this change tick.
|
|
#[inline]
|
|
pub const fn get(self) -> u32 {
|
|
self.tick
|
|
}
|
|
|
|
/// Sets the value of this change tick.
|
|
#[inline]
|
|
pub fn set(&mut self, tick: u32) {
|
|
self.tick = tick;
|
|
}
|
|
|
|
/// Returns `true` if this `Tick` occurred since the system's `last_run`.
|
|
///
|
|
/// `this_run` is the current tick of the system, used as a reference to help deal with wraparound.
|
|
#[inline]
|
|
pub fn is_newer_than(self, last_run: Tick, this_run: Tick) -> bool {
|
|
// This works even with wraparound because the world tick (`this_run`) is always "newer" than
|
|
// `last_run` and `self.tick`, and we scan periodically to clamp `ComponentTicks` values
|
|
// so they never get older than `u32::MAX` (the difference would overflow).
|
|
//
|
|
// The clamp here ensures determinism (since scans could differ between app runs).
|
|
let ticks_since_insert = this_run.relative_to(self).tick.min(MAX_CHANGE_AGE);
|
|
let ticks_since_system = this_run.relative_to(last_run).tick.min(MAX_CHANGE_AGE);
|
|
|
|
ticks_since_system > ticks_since_insert
|
|
}
|
|
|
|
/// Returns a change tick representing the relationship between `self` and `other`.
|
|
#[inline]
|
|
pub(crate) fn relative_to(self, other: Self) -> Self {
|
|
let tick = self.tick.wrapping_sub(other.tick);
|
|
Self { tick }
|
|
}
|
|
|
|
/// Wraps this change tick's value if it exceeds [`Tick::MAX`].
|
|
///
|
|
/// Returns `true` if wrapping was performed. Otherwise, returns `false`.
|
|
#[inline]
|
|
pub(crate) fn check_tick(&mut self, tick: Tick) -> bool {
|
|
let age = tick.relative_to(*self);
|
|
// This comparison assumes that `age` has not overflowed `u32::MAX` before, which will be true
|
|
// so long as this check always runs before that can happen.
|
|
if age.get() > Self::MAX.get() {
|
|
*self = tick.relative_to(Self::MAX);
|
|
true
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Interior-mutable access to the [`Tick`]s for a single component or resource.
|
|
#[derive(Copy, Clone, Debug)]
|
|
pub struct TickCells<'a> {
|
|
/// The tick indicating when the value was added to the world.
|
|
pub added: &'a UnsafeCell<Tick>,
|
|
/// The tick indicating the last time the value was modified.
|
|
pub changed: &'a UnsafeCell<Tick>,
|
|
}
|
|
|
|
impl<'a> TickCells<'a> {
|
|
/// # Safety
|
|
/// All cells contained within must uphold the safety invariants of [`UnsafeCellDeref::read`].
|
|
#[inline]
|
|
pub(crate) unsafe fn read(&self) -> ComponentTicks {
|
|
ComponentTicks {
|
|
added: self.added.read(),
|
|
changed: self.changed.read(),
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Records when a component was added and when it was last mutably dereferenced (or added).
|
|
#[derive(Copy, Clone, Debug)]
|
|
pub struct ComponentTicks {
|
|
pub(crate) added: Tick,
|
|
pub(crate) changed: Tick,
|
|
}
|
|
|
|
impl ComponentTicks {
|
|
/// Returns `true` if the component was added after the system last ran.
|
|
#[inline]
|
|
pub fn is_added(&self, last_run: Tick, this_run: Tick) -> bool {
|
|
self.added.is_newer_than(last_run, this_run)
|
|
}
|
|
|
|
/// Returns `true` if the component was added or mutably dereferenced after the system last ran.
|
|
#[inline]
|
|
pub fn is_changed(&self, last_run: Tick, this_run: Tick) -> bool {
|
|
self.changed.is_newer_than(last_run, this_run)
|
|
}
|
|
|
|
/// Returns the tick recording the time this component was most recently changed.
|
|
#[inline]
|
|
pub fn last_changed_tick(&self) -> Tick {
|
|
self.changed
|
|
}
|
|
|
|
/// Returns the tick recording the time this component was added.
|
|
#[inline]
|
|
pub fn added_tick(&self) -> Tick {
|
|
self.added
|
|
}
|
|
|
|
pub(crate) fn new(change_tick: Tick) -> Self {
|
|
Self {
|
|
added: change_tick,
|
|
changed: change_tick,
|
|
}
|
|
}
|
|
|
|
/// Manually sets the change tick.
|
|
///
|
|
/// This is normally done automatically via the [`DerefMut`](std::ops::DerefMut) implementation
|
|
/// on [`Mut<T>`](crate::change_detection::Mut), [`ResMut<T>`](crate::change_detection::ResMut), etc.
|
|
/// However, components and resources that make use of interior mutability might require manual updates.
|
|
///
|
|
/// # Example
|
|
/// ```rust,no_run
|
|
/// # use bevy_ecs::{world::World, component::ComponentTicks};
|
|
/// let world: World = unimplemented!();
|
|
/// let component_ticks: ComponentTicks = unimplemented!();
|
|
///
|
|
/// component_ticks.set_changed(world.read_change_tick());
|
|
/// ```
|
|
#[inline]
|
|
pub fn set_changed(&mut self, change_tick: Tick) {
|
|
self.changed = change_tick;
|
|
}
|
|
}
|
|
|
|
/// Initialize and fetch a [`ComponentId`] for a specific type.
|
|
///
|
|
/// # Example
|
|
/// ```rust
|
|
/// # use bevy_ecs::{system::Local, component::{Component, ComponentId, ComponentIdFor}};
|
|
/// #[derive(Component)]
|
|
/// struct Player;
|
|
/// fn my_system(component_id: Local<ComponentIdFor<Player>>) {
|
|
/// let component_id: ComponentId = component_id.into();
|
|
/// // ...
|
|
/// }
|
|
/// ```
|
|
pub struct ComponentIdFor<T: Component> {
|
|
component_id: ComponentId,
|
|
phantom: PhantomData<T>,
|
|
}
|
|
|
|
impl<T: Component> FromWorld for ComponentIdFor<T> {
|
|
fn from_world(world: &mut World) -> Self {
|
|
Self {
|
|
component_id: world.init_component::<T>(),
|
|
phantom: PhantomData,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: Component> std::ops::Deref for ComponentIdFor<T> {
|
|
type Target = ComponentId;
|
|
fn deref(&self) -> &Self::Target {
|
|
&self.component_id
|
|
}
|
|
}
|
|
|
|
impl<T: Component> From<ComponentIdFor<T>> for ComponentId {
|
|
fn from(to_component_id: ComponentIdFor<T>) -> ComponentId {
|
|
*to_component_id
|
|
}
|
|
}
|
|
|
|
impl<'s, T: Component> From<Local<'s, ComponentIdFor<T>>> for ComponentId {
|
|
fn from(to_component_id: Local<ComponentIdFor<T>>) -> ComponentId {
|
|
**to_component_id
|
|
}
|
|
}
|