Struct ComponentLookup<T>

A [NativeContainer] that provides access to all instances of components of type T, indexed by Entity.

Namespace: Unity.Entities

Assembly: Unity.Entities.dll

Syntax

[NativeContainer]
public struct ComponentLookup<T> where T : unmanaged, IComponentData

Type Parameters

Name	Description
T	The type of IComponentData to access.

Remarks

ComponentLookup is a native container that provides array-like access to components of a specific type. You can use ComponentLookup to look up data associated with one entity while iterating over a different set of entities. For example, Unity.Transforms stores the Entity object of parent entities in a Parent component and looks up the parent's LocalToWorld matrix using ComponentLookup<LocalToWorld> when calculating the world positions of child entities.

To get a ComponentLookup, call GetComponentLookup<T>(bool).

Pass a ComponentLookup container to a job by defining a public field of the appropriate type in your IJob implementation. You can safely read from ComponentLookup in any job, but by default, you cannot write to components in the container in parallel jobs (including IJobEntity, Entities.Foreach and IJobChunk). If you know that two instances of a parallel job can never write to the same index in the container, you can disable the restriction on parallel writing by adding NativeDisableParallelForRestrictionAttribute to the ComponentLookup field definition in the job struct.

If you would like to access an entity's components outside of a job, consider using the EntityManager methods GetComponentData<T>(Entity) and SetComponentData<T>(Entity, T) instead, to avoid the overhead of creating a ComponentLookup object.

Properties

Name	Description
this[Entity]	Gets the IComponentData instance of type T for the specified entity.
this[SystemHandle]	Gets the IComponentData instance of type T for the specified system's associated entity.

Methods

Name	Description
DidChange(Entity, uint)	Reports whether any of IComponentData components of the type T, in the chunk containing the specified Entity, could have changed.
EntityExists(Entity)	Reports whether the specified entity exists. Does not consider whether this component exists on the given entity.
GetComponentEnabledRefROOptional<T2>(Entity)	Obsolete. Use GetEnabledRefROOptional<T2>(Entity) instead.
GetComponentEnabledRefRWOptional<T2>(Entity)	Obsolete. Use GetEnabledRefRWOptional<T2>(Entity) instead.
GetEnabledRefROOptional<T2>(Entity)	Gets a safe reference to the component enabled state.
GetEnabledRefRO<T2>(Entity)	Gets a safe reference to the component enabled state.
GetEnabledRefRWOptional<T2>(Entity)	Gets a safe reference to the component enabled state.
GetEnabledRefRW<T2>(Entity)	Gets a safe reference to the component enabled state.
GetRefRO(Entity)	Gets a safe reference to the component data.
GetRefROOptional(Entity)	Gets a safe reference to the component data and a default RefRO (RefRO.IsValid == false).
GetRefRW(Entity)	Gets a safe reference to the component data.
GetRefRW(SystemHandle)	Gets a safe reference to the component data.
GetRefRWOptional(Entity)	Gets a safe reference to the component data and a default RefRW (RefRW.IsValid == false). ///
HasComponent(Entity)	Reports whether the specified Entity instance still refers to a valid entity and that it has a component of type T.
HasComponent(Entity, out bool)	Reports whether the specified Entity instance still refers to a valid entity and that it has a component of type T.
HasComponent(SystemHandle)	Reports whether the specified SystemHandle associated Entity is valid and contains a component of type T.
IsComponentEnabled(Entity)	Checks whether the IComponentData of type T is enabled on the specified Entity. For the purposes of EntityQuery matching, an entity with a disabled component will behave as if it does not have that component. The type T must implement the IEnableableComponent interface.
IsComponentEnabled(SystemHandle)	Checks whether the IComponentData of type T is enabled on the specified system using a SystemHandle. For the purposes of EntityQuery matching, a system with a disabled component will behave as if it does not have that component. The type T must implement the IEnableableComponent interface.
SetComponentEnabled(Entity, bool)	Enable or disable the IComponentData of type T on the specified Entity. This operation does not cause a structural change (even if it occurs on a worker thread), or affect the value of the component. For the purposes of EntityQuery matching, an entity with a disabled component will behave as if it does not have that component. The type T must implement the IEnableableComponent interface.
SetComponentEnabled(SystemHandle, bool)	Enable or disable the IComponentData of type T on the specified system using a SystemHandle. This operation does not cause a structural change (even if it occurs on a worker thread), or affect the value of the component. For the purposes of EntityQuery matching, a system with a disabled component will behave as if it does not have that component. The type T must implement the IEnableableComponent interface.
TryGetComponent(Entity, out T)	Retrieves the component associated with the specified Entity, if it exists. Then reports if the instance still refers to a valid entity and that it has a component of type T.
TryGetComponent(Entity, out T, out bool)	Retrieves the component associated with the specified Entity, if it exists. Then reports if the instance still refers to a valid entity and that it has a component of type T.
Update(SystemBase)	When a ComponentLookup is cached by a system across multiple system updates, calling this function inside the system's OnUpdate() method performs the minimal incremental updates necessary to make the type handle safe to use.
Update(ref SystemState)	When a ComponentLookup is cached by a system across multiple system updates, calling this function inside the system's OnUpdate() method performs the minimal incremental updates necessary to make the type handle safe to use.