pub struct World { /* private fields */ }
Expand description
Stores and exposes operations on entities, components, resources, and their associated metadata.
Each Entity has a set of components. Each component can have up to one instance of each component type. Entity components can be created, updated, removed, and queried using a given World.
Resources
Worlds can also store resources, which are unique instances of a given type that don’t belong to a specific Entity. There are also non send resources, which can only be accessed on the main thread.
Usage of global resources
- Insert the resource into the
World
, usingWorld::insert_resource
. - Fetch the resource from a system, using
Res
orResMut
.
struct MyResource { value: u32 }
world.insert_resource(MyResource { value: 42 });
fn read_resource_system(resource: Res<MyResource>) {
assert_eq!(resource.value, 42);
}
fn write_resource_system(mut resource: ResMut<MyResource>) {
assert_eq!(resource.value, 42);
resource.value = 0;
assert_eq!(resource.value, 0);
}
Implementations
sourceimpl World
impl World
sourcepub fn entities_mut(&mut self) -> &mut Entities
pub fn entities_mut(&mut self) -> &mut Entities
Retrieves this world’s Entities collection mutably
sourcepub fn archetypes(&self) -> &Archetypes
pub fn archetypes(&self) -> &Archetypes
Retrieves this world’s Archetypes collection
sourcepub fn components(&self) -> &Components
pub fn components(&self) -> &Components
Retrieves this world’s Components collection
sourcepub fn components_mut(&mut self) -> &mut Components
pub fn components_mut(&mut self) -> &mut Components
Retrieves a mutable reference to this world’s Components collection
sourcepub fn cell(&mut self) -> WorldCell<'_>
pub fn cell(&mut self) -> WorldCell<'_>
Retrieves a WorldCell
, which safely enables multiple mutable World accesses at the same
time, provided those accesses do not conflict with each other.
pub fn init_component<T: Component>(&mut self) -> ComponentId
sourcepub fn entity(&self, entity: Entity) -> EntityRef<'_>
pub fn entity(&self, entity: Entity) -> EntityRef<'_>
Retrieves an EntityRef
that exposes read-only operations for the given entity
.
This will panic if the entity
does not exist. Use World::get_entity
if you want
to check for entity existence instead of implicitly panic-ing.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 })
.id();
let position = world.entity(entity).get::<Position>().unwrap();
assert_eq!(position.x, 0.0);
sourcepub fn entity_mut(&mut self, entity: Entity) -> EntityMut<'_>
pub fn entity_mut(&mut self, entity: Entity) -> EntityMut<'_>
Retrieves an EntityMut
that exposes read and write operations for the given entity
.
This will panic if the entity
does not exist. Use World::get_entity_mut
if you want
to check for entity existence instead of implicitly panic-ing.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 })
.id();
let mut position = world.entity_mut(entity).get_mut::<Position>().unwrap();
position.x = 1.0;
sourcepub fn get_or_spawn(&mut self, entity: Entity) -> Option<EntityMut<'_>>
pub fn get_or_spawn(&mut self, entity: Entity) -> Option<EntityMut<'_>>
Returns an EntityMut
for the given entity
(if it exists) or spawns one if it doesn’t exist.
This will return None
if the entity
exists with a different generation.
Note
Spawning a specific entity
value is rarely the right choice. Most apps should favor World::spawn
.
This method should generally only be used for sharing entities across apps, and only when they have a
scheme worked out to share an ID space (which doesn’t happen by default).
sourcepub fn get_entity(&self, entity: Entity) -> Option<EntityRef<'_>>
pub fn get_entity(&self, entity: Entity) -> Option<EntityRef<'_>>
Retrieves an EntityRef
that exposes read-only operations for the given entity
.
Returns None
if the entity
does not exist. Use World::entity
if you don’t want
to unwrap the EntityRef
yourself.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 })
.id();
let entity_ref = world.get_entity(entity).unwrap();
let position = entity_ref.get::<Position>().unwrap();
assert_eq!(position.x, 0.0);
sourcepub fn get_entity_mut(&mut self, entity: Entity) -> Option<EntityMut<'_>>
pub fn get_entity_mut(&mut self, entity: Entity) -> Option<EntityMut<'_>>
Retrieves an EntityMut
that exposes read and write operations for the given entity
.
Returns None
if the entity
does not exist. Use World::entity_mut
if you don’t want
to unwrap the EntityMut
yourself.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 })
.id();
let mut entity_mut = world.get_entity_mut(entity).unwrap();
let mut position = entity_mut.get_mut::<Position>().unwrap();
position.x = 1.0;
sourcepub fn spawn(&mut self) -> EntityMut<'_>
pub fn spawn(&mut self) -> EntityMut<'_>
Spawns a new Entity
and returns a corresponding EntityMut
, which can be used
to add components to the entity or retrieve its id.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
#[derive(Component)]
struct Label(&'static str);
#[derive(Component)]
struct Num(u32);
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 }) // add a single component
.insert_bundle((Num(1), Label("hello"))) // add a bundle of components
.id();
let position = world.entity(entity).get::<Position>().unwrap();
assert_eq!(position.x, 0.0);
sourcepub fn spawn_batch<I>(&mut self, iter: I) -> SpawnBatchIter<'_, I::IntoIter>ⓘNotable traits for SpawnBatchIter<'_, I>impl<I> Iterator for SpawnBatchIter<'_, I> where
I: Iterator,
I::Item: Bundle, type Item = Entity;
where
I: IntoIterator,
I::Item: Bundle,
pub fn spawn_batch<I>(&mut self, iter: I) -> SpawnBatchIter<'_, I::IntoIter>ⓘNotable traits for SpawnBatchIter<'_, I>impl<I> Iterator for SpawnBatchIter<'_, I> where
I: Iterator,
I::Item: Bundle, type Item = Entity;
where
I: IntoIterator,
I::Item: Bundle,
I: Iterator,
I::Item: Bundle, type Item = Entity;
Spawns a batch of entities with the same component Bundle type. Takes a given Bundle iterator and returns a corresponding Entity iterator. This is more efficient than spawning entities and adding components to them individually, but it is limited to spawning entities with the same Bundle type, whereas spawning individually is more flexible.
use bevy_ecs::{component::Component, entity::Entity, world::World};
#[derive(Component)]
struct Str(&'static str);
#[derive(Component)]
struct Num(u32);
let mut world = World::new();
let entities = world.spawn_batch(vec![
(Str("a"), Num(0)), // the first entity
(Str("b"), Num(1)), // the second entity
]).collect::<Vec<Entity>>();
assert_eq!(entities.len(), 2);
sourcepub fn get<T: Component>(&self, entity: Entity) -> Option<&T>
pub fn get<T: Component>(&self, entity: Entity) -> Option<&T>
Retrieves a reference to the given entity
’s Component of the given type.
Returns None if the entity
does not have a Component of the given type.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 })
.id();
let position = world.get::<Position>(entity).unwrap();
assert_eq!(position.x, 0.0);
sourcepub fn get_mut<T: Component>(&mut self, entity: Entity) -> Option<Mut<'_, T>>
pub fn get_mut<T: Component>(&mut self, entity: Entity) -> Option<Mut<'_, T>>
Retrieves a mutable reference to the given entity
’s Component of the given type.
Returns None if the entity
does not have a Component of the given type.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 })
.id();
let mut position = world.get_mut::<Position>(entity).unwrap();
position.x = 1.0;
sourcepub fn despawn(&mut self, entity: Entity) -> bool
pub fn despawn(&mut self, entity: Entity) -> bool
Despawns the given entity
, if it exists. This will also remove all of the entity’s
Components. Returns true
if the entity
is successfully despawned and false
if
the entity
does not exist.
use bevy_ecs::{component::Component, world::World};
#[derive(Component)]
struct Position {
x: f32,
y: f32,
}
let mut world = World::new();
let entity = world.spawn()
.insert(Position { x: 0.0, y: 0.0 })
.id();
assert!(world.despawn(entity));
assert!(world.get_entity(entity).is_none());
assert!(world.get::<Position>(entity).is_none());
sourcepub fn clear_trackers(&mut self)
pub fn clear_trackers(&mut self)
Clears component tracker state
sourcepub fn query<Q: WorldQuery>(&mut self) -> QueryState<Q, ()>
pub fn query<Q: WorldQuery>(&mut self) -> QueryState<Q, ()>
Returns QueryState
for the given WorldQuery
, which is used to efficiently
run queries on the World
by storing and reusing the QueryState
.
use bevy_ecs::{component::Component, entity::Entity, world::World};
#[derive(Component, Debug, PartialEq)]
struct Position {
x: f32,
y: f32,
}
#[derive(Component)]
struct Velocity {
x: f32,
y: f32,
}
let mut world = World::new();
let entities = world.spawn_batch(vec![
(Position { x: 0.0, y: 0.0}, Velocity { x: 1.0, y: 0.0 }),
(Position { x: 0.0, y: 0.0}, Velocity { x: 0.0, y: 1.0 }),
]).collect::<Vec<Entity>>();
let mut query = world.query::<(&mut Position, &Velocity)>();
for (mut position, velocity) in query.iter_mut(&mut world) {
position.x += velocity.x;
position.y += velocity.y;
}
assert_eq!(world.get::<Position>(entities[0]).unwrap(), &Position { x: 1.0, y: 0.0 });
assert_eq!(world.get::<Position>(entities[1]).unwrap(), &Position { x: 0.0, y: 1.0 });
To iterate over entities in a deterministic order, sort the results of the query using the desired component as a key. Note that this requires fetching the whole result set from the query and allocation of a Vec to store it.
use bevy_ecs::{component::Component, entity::Entity, world::World};
#[derive(Component, PartialEq, Eq, PartialOrd, Ord, Debug)]
struct Order(i32);
#[derive(Component, PartialEq, Debug)]
struct Label(&'static str);
let mut world = World::new();
let a = world.spawn().insert_bundle((Order(2), Label("second"))).id();
let b = world.spawn().insert_bundle((Order(3), Label("third"))).id();
let c = world.spawn().insert_bundle((Order(1), Label("first"))).id();
let mut entities = world.query::<(Entity, &Order, &Label)>()
.iter(&world)
.collect::<Vec<_>>();
// Sort the query results by their `Order` component before comparing
// to expected results. Query iteration order should not be relied on.
entities.sort_by_key(|e| e.1);
assert_eq!(entities, vec![
(c, &Order(1), &Label("first")),
(a, &Order(2), &Label("second")),
(b, &Order(3), &Label("third")),
]);
sourcepub fn query_filtered<Q: WorldQuery, F: WorldQuery>(
&mut self
) -> QueryState<Q, F> where
F::Fetch: FilterFetch,
pub fn query_filtered<Q: WorldQuery, F: WorldQuery>(
&mut self
) -> QueryState<Q, F> where
F::Fetch: FilterFetch,
Returns QueryState
for the given filtered WorldQuery
, which is used to efficiently
run queries on the World
by storing and reusing the QueryState
.
use bevy_ecs::{component::Component, entity::Entity, world::World, query::With};
#[derive(Component)]
struct A;
#[derive(Component)]
struct B;
let mut world = World::new();
let e1 = world.spawn().insert(A).id();
let e2 = world.spawn().insert_bundle((A, B)).id();
let mut query = world.query_filtered::<Entity, With<B>>();
let matching_entities = query.iter(&world).collect::<Vec<Entity>>();
assert_eq!(matching_entities, vec![e2]);
sourcepub fn removed<T: Component>(&self) -> Cloned<Iter<'_, Entity>>
pub fn removed<T: Component>(&self) -> Cloned<Iter<'_, Entity>>
Returns an iterator of entities that had components of type T
removed
since the last call to World::clear_trackers
.
sourcepub fn removed_with_id(
&self,
component_id: ComponentId
) -> Cloned<Iter<'_, Entity>>
pub fn removed_with_id(
&self,
component_id: ComponentId
) -> Cloned<Iter<'_, Entity>>
Returns an iterator of entities that had components with the given component_id
removed
since the last call to World::clear_trackers
.
sourcepub fn insert_resource<T: Resource>(&mut self, value: T)
pub fn insert_resource<T: Resource>(&mut self, value: T)
Inserts a new resource with the given value
.
Resources are “unique” data of a given type.
sourcepub fn insert_non_send<T: 'static>(&mut self, value: T)
pub fn insert_non_send<T: 'static>(&mut self, value: T)
Inserts a new non-send resource with the given value
.
Resources are “unique” data of a given type.
sourcepub fn remove_resource<T: Resource>(&mut self) -> Option<T>
pub fn remove_resource<T: Resource>(&mut self) -> Option<T>
Removes the resource of a given type and returns it, if it exists. Otherwise returns None. Resources are “unique” data of a given type.
pub fn remove_non_send<T: 'static>(&mut self) -> Option<T>
sourcepub unsafe fn remove_resource_unchecked<T: 'static>(&mut self) -> Option<T>
pub unsafe fn remove_resource_unchecked<T: 'static>(&mut self) -> Option<T>
Safety
make sure you’re on main thread if T isn’t Send + Sync
sourcepub fn contains_resource<T: Resource>(&self) -> bool
pub fn contains_resource<T: Resource>(&self) -> bool
Returns true
if a resource of type T
exists. Otherwise returns false
.
sourcepub fn get_resource<T: Resource>(&self) -> Option<&T>
pub fn get_resource<T: Resource>(&self) -> Option<&T>
Gets a reference to the resource of the given type, if it exists. Otherwise returns None Resources are “unique” data of a given type.
pub fn is_resource_added<T: Resource>(&self) -> bool
pub fn is_resource_changed<T: Resource>(&self) -> bool
sourcepub fn get_resource_mut<T: Resource>(&mut self) -> Option<Mut<'_, T>>
pub fn get_resource_mut<T: Resource>(&mut self) -> Option<Mut<'_, T>>
Gets a mutable reference to the resource of the given type, if it exists. Otherwise returns None Resources are “unique” data of a given type.
sourcepub fn get_resource_or_insert_with<T: Resource>(
&mut self,
func: impl FnOnce() -> T
) -> Mut<'_, T>
pub fn get_resource_or_insert_with<T: Resource>(
&mut self,
func: impl FnOnce() -> T
) -> Mut<'_, T>
Gets a resource of type T
if it exists, otherwise inserts the resource using the result of
calling func
.
sourcepub unsafe fn get_resource_unchecked_mut<T: Resource>(
&self
) -> Option<Mut<'_, T>>
pub unsafe fn get_resource_unchecked_mut<T: Resource>(
&self
) -> Option<Mut<'_, T>>
sourcepub fn get_non_send_resource<T: 'static>(&self) -> Option<&T>
pub fn get_non_send_resource<T: 'static>(&self) -> Option<&T>
Gets a reference to the non-send resource of the given type, if it exists. Otherwise returns None Resources are “unique” data of a given type.
sourcepub fn get_non_send_resource_mut<T: 'static>(&mut self) -> Option<Mut<'_, T>>
pub fn get_non_send_resource_mut<T: 'static>(&mut self) -> Option<Mut<'_, T>>
Gets a mutable reference to the non-send resource of the given type, if it exists. Otherwise returns None Resources are “unique” data of a given type.
sourcepub unsafe fn get_non_send_resource_unchecked_mut<T: 'static>(
&self
) -> Option<Mut<'_, T>>
pub unsafe fn get_non_send_resource_unchecked_mut<T: 'static>(
&self
) -> Option<Mut<'_, T>>
Gets a mutable reference to the non-send resource of the given type, if it exists. Otherwise returns None Resources are “unique” data of a given type.
Safety
This will allow aliased mutable access to the given non-send resource type. The caller must ensure that only one mutable access exists at a time.
sourcepub fn insert_or_spawn_batch<I, B>(
&mut self,
iter: I
) -> Result<(), Vec<Entity>> where
I: IntoIterator,
I::IntoIter: Iterator<Item = (Entity, B)>,
B: Bundle,
pub fn insert_or_spawn_batch<I, B>(
&mut self,
iter: I
) -> Result<(), Vec<Entity>> where
I: IntoIterator,
I::IntoIter: Iterator<Item = (Entity, B)>,
B: Bundle,
For a given batch of (Entity, Bundle) pairs, either spawns each Entity with the given bundle (if the entity does not exist), or inserts the Bundle (if the entity already exists). This is faster than doing equivalent operations one-by-one. Returns Ok if all entities were successfully inserted into or spawned. Otherwise it returns an Err with a list of entities that could not be spawned or inserted into. A “spawn or insert” operation can only fail if an Entity is passed in with an “invalid generation” that conflicts with an existing Entity.
Note
Spawning a specific entity
value is rarely the right choice. Most apps should use World::spawn_batch
.
This method should generally only be used for sharing entities across apps, and only when they have a scheme
worked out to share an ID space (which doesn’t happen by default).
use bevy_ecs::{entity::Entity, world::World, component::Component};
#[derive(Component)]
struct A(&'static str);
#[derive(Component, PartialEq, Debug)]
struct B(f32);
let mut world = World::new();
let e0 = world.spawn().id();
let e1 = world.spawn().id();
world.insert_or_spawn_batch(vec![
(e0, (A("a"), B(0.0))), // the first entity
(e1, (A("b"), B(1.0))), // the second entity
]);
assert_eq!(world.get::<B>(e0), Some(&B(0.0)));
sourcepub fn resource_scope<T: Resource, U>(
&mut self,
f: impl FnOnce(&mut World, Mut<'_, T>) -> U
) -> U
pub fn resource_scope<T: Resource, U>(
&mut self,
f: impl FnOnce(&mut World, Mut<'_, T>) -> U
) -> U
Temporarily removes the requested resource from this World, then re-adds it before returning. This enables safe mutable access to a resource while still providing mutable world access
use bevy_ecs::{component::Component, world::{World, Mut}};
#[derive(Component)]
struct A(u32);
#[derive(Component)]
struct B(u32);
let mut world = World::new();
world.insert_resource(A(1));
let entity = world.spawn().insert(B(1)).id();
world.resource_scope(|world, mut a: Mut<A>| {
let b = world.get_mut::<B>(entity).unwrap();
a.0 += b.0;
});
assert_eq!(world.get_resource::<A>().unwrap().0, 2);
pub fn increment_change_tick(&self) -> u32
pub fn read_change_tick(&self) -> u32
pub fn change_tick(&mut self) -> u32
pub fn last_change_tick(&self) -> u32
pub fn check_change_ticks(&mut self)
pub fn clear_entities(&mut self)
Trait Implementations
sourceimpl<F> IntoExclusiveSystem<&'_ mut World, ExclusiveSystemFn<F>> for F where
F: FnMut(&mut World) + Send + Sync + 'static,
impl<F> IntoExclusiveSystem<&'_ mut World, ExclusiveSystemFn<F>> for F where
F: FnMut(&mut World) + Send + Sync + 'static,
fn exclusive_system(self) -> ExclusiveSystemFn<F>
impl Send for World
impl Sync for World
Auto Trait Implementations
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcepub fn borrow_mut(&mut self) -> &mut T
pub fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> Downcast for T where
T: Any,
impl<T> Downcast for T where
T: Any,
sourcepub fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>
pub fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>
Convert Box<dyn Trait>
(where Trait: Downcast
) to Box<dyn Any>
. Box<dyn Any>
can
then be further downcast
into Box<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcepub fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
pub fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
Convert Rc<Trait>
(where Trait: Downcast
) to Rc<Any>
. Rc<Any>
can then be
further downcast
into Rc<ConcreteType>
where ConcreteType
implements Trait
. Read more
sourcepub fn as_any(&self) -> &(dyn Any + 'static)
pub fn as_any(&self) -> &(dyn Any + 'static)
Convert &Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &Any
’s vtable from &Trait
’s. Read more
sourcepub fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
pub fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
Convert &mut Trait
(where Trait: Downcast
) to &Any
. This is needed since Rust cannot
generate &mut Any
’s vtable from &mut Trait
’s. Read more
sourceimpl<T> DowncastSync for T where
T: Any + Send + Sync,
impl<T> DowncastSync for T where
T: Any + Send + Sync,
sourceimpl<T> FromWorld for T where
T: Default,
impl<T> FromWorld for T where
T: Default,
sourcefn from_world(_world: &mut World) -> Self
fn from_world(_world: &mut World) -> Self
Creates Self
using data from the given World
sourceimpl<T> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self>
fn instrument(self, span: Span) -> Instrumented<Self>
sourcefn in_current_span(self) -> Instrumented<Self>
fn in_current_span(self) -> Instrumented<Self>
sourceimpl<T> WithSubscriber for T
impl<T> WithSubscriber for T
sourcefn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where
S: Into<Dispatch>,
fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self> where
S: Into<Dispatch>,
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
sourcefn with_current_subscriber(self) -> WithDispatch<Self>
fn with_current_subscriber(self) -> WithDispatch<Self>
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more