pub struct Added<T>(_);
Expand description
A filter on a component that only retains results added after the system last ran.
A common use for this filter is one-time initialization.
To retain all results without filtering but still check whether they were added after the
system last ran, use Ref<T>
.
Examples
fn print_add_name_component(query: Query<&Name, Added<Name>>) {
for name in &query {
println!("Named entity created: {:?}", name)
}
}
Trait Implementations§
source§impl<T: Component> WorldQuery for Added<T>
impl<T: Component> WorldQuery for Added<T>
§type Fetch<'w> = AddedFetch<'w, T>
type Fetch<'w> = AddedFetch<'w, T>
Per archetype/table state used by this
WorldQuery
to fetch Self::Item
§type Item<'w> = bool
type Item<'w> = bool
The item returned by this
WorldQuery
§type ReadOnly = Added<T>
type ReadOnly = Added<T>
The read-only variant of this
WorldQuery
, which satisfies the ReadOnlyWorldQuery
trait.§type State = ComponentId
type State = ComponentId
State used to construct a
Self::Fetch
. This will be cached inside QueryState
,
so it is best to move as much data / computation here as possible to reduce the cost of
constructing Self::Fetch
.source§fn shrink<'wlong: 'wshort, 'wshort>(
item: Self::Item<'wlong>
) -> Self::Item<'wshort>
fn shrink<'wlong: 'wshort, 'wshort>( item: Self::Item<'wlong> ) -> Self::Item<'wshort>
This function manually implements subtyping for the query items.
source§unsafe fn init_fetch<'w>(
world: &'w World,
id: &ComponentId,
last_change_tick: u32,
change_tick: u32
) -> Self::Fetch<'w>
unsafe fn init_fetch<'w>( world: &'w World, id: &ComponentId, last_change_tick: u32, change_tick: u32 ) -> Self::Fetch<'w>
Creates a new instance of this fetch. Read more
source§unsafe fn clone_fetch<'w>(fetch: &Self::Fetch<'w>) -> Self::Fetch<'w>
unsafe fn clone_fetch<'w>(fetch: &Self::Fetch<'w>) -> Self::Fetch<'w>
While this function can be called for any query, it is always safe to call if
Self: ReadOnlyWorldQuery
holds. Read moresource§const IS_DENSE: bool = _
const IS_DENSE: bool = _
Returns true if (and only if) every table of every archetype matched by this fetch contains
all of the matched components. This is used to select a more efficient “table iterator”
for “dense” queries. If this returns true,
WorldQuery::set_table
must be used before
WorldQuery::fetch
can be called for iterators. If this returns false,
WorldQuery::set_archetype
must be used before WorldQuery::fetch
can be called for
iterators.source§const IS_ARCHETYPAL: bool = false
const IS_ARCHETYPAL: bool = false
Returns true if (and only if) this Fetch relies strictly on archetypes to limit which
components are accessed by the Query. Read more
source§unsafe fn set_table<'w>(
fetch: &mut Self::Fetch<'w>,
component_id: &ComponentId,
table: &'w Table
)
unsafe fn set_table<'w>( fetch: &mut Self::Fetch<'w>, component_id: &ComponentId, table: &'w Table )
Adjusts internal state to account for the next
Table
. This will always be called on tables
that match this WorldQuery
. Read moresource§unsafe fn set_archetype<'w>(
fetch: &mut Self::Fetch<'w>,
component_id: &ComponentId,
_archetype: &'w Archetype,
table: &'w Table
)
unsafe fn set_archetype<'w>( fetch: &mut Self::Fetch<'w>, component_id: &ComponentId, _archetype: &'w Archetype, table: &'w Table )
Adjusts internal state to account for the next
Archetype
. This will always be called on
archetypes that match this WorldQuery
. Read moresource§unsafe fn fetch<'w>(
fetch: &mut Self::Fetch<'w>,
entity: Entity,
table_row: TableRow
) -> Self::Item<'w>
unsafe fn fetch<'w>( fetch: &mut Self::Fetch<'w>, entity: Entity, table_row: TableRow ) -> Self::Item<'w>
Fetch
Self::Item
for either the given entity
in the current Table
,
or for the given entity
in the current Archetype
. This must always be called after
WorldQuery::set_table
with a table_row
in the range of the current Table
or after
WorldQuery::set_archetype
with a entity
in the current archetype. Read moresource§unsafe fn filter_fetch<'w>(
fetch: &mut Self::Fetch<'w>,
entity: Entity,
table_row: TableRow
) -> bool
unsafe fn filter_fetch<'w>( fetch: &mut Self::Fetch<'w>, entity: Entity, table_row: TableRow ) -> bool
Safety Read more
fn update_component_access( id: &ComponentId, access: &mut FilteredAccess<ComponentId> )
fn update_archetype_component_access( id: &ComponentId, archetype: &Archetype, access: &mut Access<ArchetypeComponentId> )
fn init_state(world: &mut World) -> ComponentId
fn matches_component_set( id: &ComponentId, set_contains_id: &impl Fn(ComponentId) -> bool ) -> bool
impl<T: Component> ReadOnlyWorldQuery for Added<T>
SAFETY: read-only access
Auto Trait Implementations§
impl<T> RefUnwindSafe for Added<T>where T: RefUnwindSafe,
impl<T> Send for Added<T>where T: Send,
impl<T> Sync for Added<T>where T: Sync,
impl<T> Unpin for Added<T>where T: Unpin,
impl<T> UnwindSafe for Added<T>where T: UnwindSafe,
Blanket Implementations§
source§impl<T> Downcast for Twhere
T: Any,
impl<T> Downcast for Twhere T: Any,
source§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
.source§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
.source§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.source§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.