Struct bevy_ecs::query::ChangeTrackers
source · pub struct ChangeTrackers<T: Component> { /* private fields */ }
Expand description
WorldQuery
that tracks changes and additions for component T
.
Wraps a Component
to track whether the component changed for the corresponding entities in
a query since the last time the system that includes these queries ran.
If you only care about entities that changed or that got added use the
Changed
and Added
filters instead.
Examples
fn print_moving_objects_system(query: Query<(&Name, ChangeTrackers<Transform>)>) {
for (name, tracker) in &query {
if tracker.is_changed() {
println!("Entity moved: {:?}", name);
} else {
println!("Entity stood still: {:?}", name);
}
}
}
Implementations§
source§impl<T: Component> ChangeTrackers<T>
impl<T: Component> ChangeTrackers<T>
Trait Implementations§
source§impl<T: Component> Clone for ChangeTrackers<T>
impl<T: Component> Clone for ChangeTrackers<T>
source§impl<T: Component> Debug for ChangeTrackers<T>
impl<T: Component> Debug for ChangeTrackers<T>
source§impl<T: Component> WorldQuery for ChangeTrackers<T>
impl<T: Component> WorldQuery for ChangeTrackers<T>
§type Fetch<'w> = ChangeTrackersFetch<'w, T>
type Fetch<'w> = ChangeTrackersFetch<'w, T>
Per archetype/table state used by this
WorldQuery
to fetch Self::Item
§type Item<'w> = ChangeTrackers<T>
type Item<'w> = ChangeTrackers<T>
The item returned by this
WorldQuery
§type ReadOnly = ChangeTrackers<T>
type ReadOnly = ChangeTrackers<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
. Read moresource§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§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. Read moresource§const IS_ARCHETYPAL: bool = true
const IS_ARCHETYPAL: bool = true
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 init_fetch<'w>(
world: &'w World,
component_id: &ComponentId,
last_change_tick: u32,
change_tick: u32
) -> ChangeTrackersFetch<'w, T>
unsafe fn init_fetch<'w>(
world: &'w World,
component_id: &ComponentId,
last_change_tick: u32,
change_tick: u32
) -> ChangeTrackersFetch<'w, T>
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§unsafe fn set_archetype<'w>(
fetch: &mut ChangeTrackersFetch<'w, T>,
component_id: &ComponentId,
_archetype: &'w Archetype,
table: &'w Table
)
unsafe fn set_archetype<'w>(
fetch: &mut ChangeTrackersFetch<'w, T>,
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 set_table<'w>(
fetch: &mut ChangeTrackersFetch<'w, T>,
id: &ComponentId,
table: &'w Table
)
unsafe fn set_table<'w>(
fetch: &mut ChangeTrackersFetch<'w, T>,
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 fetch<'w>(
fetch: &mut Self::Fetch<'w>,
entity: Entity,
table_row: usize
) -> Self::Item<'w>
unsafe fn fetch<'w>(
fetch: &mut Self::Fetch<'w>,
entity: Entity,
table_row: usize
) -> 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 morefn 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> Copy for ChangeTrackers<T>
impl<T: Component> ReadOnlyWorldQuery for ChangeTrackers<T>
SAFETY: access is read only
Auto Trait Implementations§
impl<T> RefUnwindSafe for ChangeTrackers<T>where
T: RefUnwindSafe,
impl<T> Send for ChangeTrackers<T>
impl<T> Sync for ChangeTrackers<T>
impl<T> Unpin for ChangeTrackers<T>where
T: Unpin,
impl<T> UnwindSafe for ChangeTrackers<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
. Read moresource§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 moresource§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 moresource§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