FEntityCollection | Unreal Engine 5.7 Documentation

API > API/Runtime > API/Runtime/MassEntity

Type represents a collection of arbitrary EntityHandles. Under the hood the type stores also an array of FMassArchetypeEntityCollection instances. These cached collections can be tested for being up to date, and re-created on demand, based on stored entity handles.

The type is intended to be used to collect entities available through different means: individual handles, handle arrays and or FMassArchetypeEntityCollection instances. Such accumulated handles can at any moment be turned into an array of up-to-date FMassArchetypeEntityCollection instance, which in turn is how entity sets are provided to MassEntityManager's batched API.

The biggest win while using this type is that the user doesn't have to worry about FMassArchetypeEntityCollection instances going out of date (which happens whenever the target archetype is touched in a way that changes internal entity indices). The type automatically updates the collections and caches the result.


Name	FEntityCollection
Type	struct
Header File	/Engine/Source/Runtime/MassEntity/Public/MassEntityCollection.h
Include Path	#include "MassEntityCollection.h"

Syntax

struct FEntityCollection

Constructors

Name	Remarks	Include Path
FEntityCollection ( const FMassArchetypeEntityCollection& InEntityCollection )		MassEntityCollection.h
FEntityCollection ( FMassArchetypeEntityCollection&& InEntityCollection )	The following constructor are equivalent to using the default constructor and subsequently calling AppendCollection or AppendHandles.	MassEntityCollection.h
FEntityCollection ()		MassEntityCollection.h
FEntityCollection ( const TConstArrayView< FMassEntityHandle > InEntityHandles, FMassArchetypeEntityCollection&& InEntityCollection )		MassEntityCollection.h
FEntityCollection ( const TConstArrayView< FMassEntityHandle > InEntityHandles )		MassEntityCollection.h

Variables

Protected

Name	Type	Remarks	Include Path
CachedCollections	TArray< FMassArchetypeEntityCollection >	Cached per-archetype collections of entities.	MassEntityCollection.h
CollectionCreationDuplicatesHandling	FMassArchetypeEntityCollection::EDuplicatesHandling	Stores information whether we can expect duplicates in EntityHandles when building CachedCollections	MassEntityCollection.h
EntityHandles	TArray< FMassEntityHandle >	These are the entities represented by given instance of FEntityCollection.	MassEntityCollection.h

Functions

Public

Name	Remarks	Include Path
void AddHandle ( FMassEntityHandle Handle )	Appends the Handle to stored EntityHandles.	MassEntityCollection.h
void AppendCollection ( T&& InEntityCollection )	Based on the provided FMassArchetypeEntityCollection creates an array of entity handles and stores them.	MassEntityCollection.h
void AppendHandles ( TConstArrayView< FMassEntityHandle > Handles, FMassArchetypeEntityCollection&& InEntityCollection )	Appends Handles to stored EntityHandles.	MassEntityCollection.h
void AppendHandles ( TArray< FMassEntityHandle >&& Handles )	Appends Handles to stored EntityHandles.	MassEntityCollection.h
void AppendHandles ( TConstArrayView< FMassEntityHandle > Handles )	Mutating API	MassEntityCollection.h
TArray< FMassArchetypeEntityCollection > ConsumeArchetypeCollections ( const FMassEntityManager& EntityManager )	Updates cached archetype collections and returns the container with move semantics	MassEntityCollection.h
TConstArrayView< FMassArchetypeEntityCollection > GetCachedPerArchetypeCollections ()	Retrieves the view to current contents of CachedCollections, which may be out of date.	MassEntityCollection.h
TConstArrayView< FMassEntityHandle > GetEntityHandlesView()	Data reading API	MassEntityCollection.h
TConstArrayView< FMassArchetypeEntityCollection > GetUpToDatePerArchetypeCollections ( const FMassEntityManager& EntityManager ) const	Fetches up-to-date FMassArchetypeEntityCollection instances matching stored entity handles.	MassEntityCollection.h
bool IsEmpty()		MassEntityCollection.h
bool IsUpToDate ()	Checks if cached collection data is up to date If CachedCollections are not up-to-date we reset them to cache the information (and make the subsequent tests cheaper) Note that, depending on the contents, the test might be non-trivial.	MassEntityCollection.h
void MarkDirty()	State-querying API	MassEntityCollection.h
bool UpdateAndRemoveDuplicates ( const FMassEntityManager& EntityManager, bool bForceOperation )	Results in duplicate handles being removed from EntityHandles, the cached collections being up-to-date and CollectionCreationDuplicatesHandling being set to FMassArchetypeEntityCollection::NoDuplicates	MassEntityCollection.h