pub struct Changed<T>(_);
Expand description
A filter on a component that only retains results added or mutably dereferenced after the system last ran.
A common use for this filter is avoiding redundant work when values have not changed.
Note that simply mutably dereferencing a component is considered a change (DerefMut
).
Bevy does not compare components to their previous values.
To retain all results without filtering but still check whether they were changed after the
system last ran, use ChangeTrackers<T>
.
Examples
fn print_moving_objects_system(query: Query<&Name, Changed<Transform>>) {
for name in &query {
println!("Entity Moved: {:?}", name);
}
}
Trait Implementations
impl<T> WorldQuery for Changed<T> where
T: Component,
impl<T> WorldQuery for Changed<T> where
T: Component,
impl<'w, T> WorldQueryGats<'w> for Changed<T> where
T: Component,
impl<'w, T> WorldQueryGats<'w> for Changed<T> where
T: Component,
impl<T> ReadOnlyWorldQuery for Changed<T> where
T: Component,
SAFETY: read-only access
Auto Trait Implementations
impl<T> RefUnwindSafe for Changed<T> where
T: RefUnwindSafe,
impl<T> Send for Changed<T> where
T: Send,
impl<T> Sync for Changed<T> where
T: Sync,
impl<T> Unpin for Changed<T> where
T: Unpin,
impl<T> UnwindSafe for Changed<T> where
T: UnwindSafe,
Blanket Implementations
impl<T, U> AsBindGroupShaderType<U> for T where
U: ShaderType,
&'a T: for<'a> Into<U>,
impl<T, U> AsBindGroupShaderType<U> for T where
U: ShaderType,
&'a T: for<'a> Into<U>,
fn as_bind_group_shader_type(
&self,
_images: &HashMap<Handle<Image>, <Image as RenderAsset>::PreparedAsset, RandomState, Global>
) -> U
fn as_bind_group_shader_type(
&self,
_images: &HashMap<Handle<Image>, <Image as RenderAsset>::PreparedAsset, RandomState, Global>
) -> U
Return the T
ShaderType
for self
. When used in AsBindGroup
derives, it is safe to assume that all images in self
exist. Read more
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
impl<T> Downcast for T where
T: Any,
impl<T> Downcast for T where
T: Any,
fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>
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
fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>
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
fn as_any(&self) -> &(dyn Any + 'static)
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
fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)
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> Instrument for T
impl<T> Instrument for T
sourcefn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
fn instrument(self, span: Span) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
sourcefn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
fn in_current_span(self) -> Instrumented<Self>ⓘNotable traits for Instrumented<T>impl<T> Future for Instrumented<T> where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
sourceimpl<T> WithSubscriber for T
impl<T> WithSubscriber for T
sourcefn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
where
S: Into<Dispatch>,
fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
where
S: Into<Dispatch>,
T: Future, type Output = <T as Future>::Output;
Attaches the provided Subscriber
to this type, returning a
WithDispatch
wrapper. Read more
sourcefn with_current_subscriber(self) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
fn with_current_subscriber(self) -> WithDispatch<Self>ⓘNotable traits for WithDispatch<T>impl<T> Future for WithDispatch<T> where
T: Future, type Output = <T as Future>::Output;
T: Future, type Output = <T as Future>::Output;
Attaches the current default Subscriber
to this type, returning a
WithDispatch
wrapper. Read more