Module entity 

Entity handling types.

An entity exclusively owns zero or more component instances, all of different types, and can dynamically acquire or lose them over its lifetime.

empty entity: Entity with zero components. pending entity: Entity reserved, but not flushed yet (see Entities::flush docs for reference). reserved entity: same as pending entity. invalid entity: pending entity flushed with invalid (see Entities::flush_as_invalid docs for reference).

See Entity to learn more.

Usage

Operations involving entities and their components are performed either from a system by submitting commands, or from the outside (or from an exclusive system) by directly using World methods:

Operation	Command	Method
Spawn an entity with components	Commands::spawn	World::spawn
Spawn an entity without components	Commands::spawn_empty	World::spawn_empty
Despawn an entity	EntityCommands::despawn	World::despawn
Insert a component, bundle, or tuple of components and bundles to an entity	EntityCommands::insert	EntityWorldMut::insert
Remove a component, bundle, or tuple of components and bundles from an entity	EntityCommands::remove	EntityWorldMut::remove

Modules

hash_map

Contains the EntityHashMap type, a HashMap pre-configured to use EntityHash hashing.

hash_set

Contains the EntityHashSet type, a HashSet pre-configured to use EntityHash hashing.

index_map

Contains the EntityIndexMap type, an IndexMap pre-configured to use EntityHash hashing.

index_set

Contains the EntityIndexSet type, a IndexSet pre-configured to use EntityHash hashing.

unique_array

A wrapper around entity arrays with a uniqueness invariant.

unique_slice

A wrapper around entity slices with a uniqueness invariant.

unique_vec

A wrapper around entity Vecs with a uniqueness invariant.

Structs

ComponentCloneCtx

Context for component clone handlers.

Entities

A World’s internal metadata store on all of its entities.

Entity

Lightweight identifier of an entity.

EntityCloner

A configuration determining how to clone entities. This can be built using EntityCloner::build_opt_out/ opt_in, which returns an EntityClonerBuilder.

EntityClonerBuilder

A builder for configuring EntityCloner. See EntityCloner for more information.

EntityDoesNotExistDetails

Helper struct that, when printed, will write the appropriate details regarding an entity that did not exist.

EntityDoesNotExistError

An error that occurs when a specified Entity does not exist.

EntityGeneration

This tracks different versions or generations of an EntityRow. Importantly, this can wrap, meaning each generation is not necessarily unique per EntityRow.

EntityHash

A BuildHasher that results in a EntityHasher.

EntityHashMap

A HashMap pre-configured to use EntityHash hashing.

EntityHashSet

A HashSet pre-configured to use EntityHash hashing.

EntityHasher

A very fast hash that is only designed to work on generational indices like Entity. It will panic if attempting to hash a type containing non-u64 fields.

EntityIndexMap

A IndexMap pre-configured to use EntityHash hashing.

EntityIndexSet

An IndexSet pre-configured to use EntityHash hashing.

EntityLocation

A location of an entity in an archetype.

EntityRow

This represents the row or “index” of an Entity within the Entities table. This is a lighter weight version of Entity.

OptIn

Generic for EntityClonerBuilder that makes the cloner try to clone every component that was explicitly allowed from the source entity, for example by using the allow method.

OptOut

Generic for EntityClonerBuilder that makes the cloner try to clone every component from the source entity except for components that were explicitly denied, for example by using the deny method.

ReserveEntitiesIterator

An Iterator returning a sequence of Entity values from

SceneEntityMapper

A wrapper for EntityHashMap<Entity>, augmenting it with the ability to allocate new Entity references in a destination world. These newly allocated references are guaranteed to never point to any living entity in that world.

SourceComponent

Provides read access to the source component (the component being cloned) in a ComponentCloneFn.

UniqueEntityEquivalentArray

An array that contains only unique entities.

UniqueEntityEquivalentSlice

A slice that contains only unique entities.

UniqueEntityEquivalentVec

A Vec that contains only unique entities.

UniqueEntityIter

An iterator that yields unique entities.

Traits

ContainsEntity

A trait for types that contain an Entity.

EntityEquivalent

A trait for types that represent an Entity.

EntityMapper

An implementor of this trait knows how to map an Entity into another Entity.

EntitySet

A set of unique entities.

EntitySetIterator

An iterator over a set of unique entities.

FromEntitySetIterator

Conversion from an EntitySetIterator.

MapEntities

Operation to map all contained Entity fields in a type to new values.

Type Aliases

EntityIdLocation

An Entity id may or may not correspond to a valid conceptual entity. If it does, the conceptual entity may or may not have a location. If it has no location, the EntityLocation will be None. An location of None means the entity effectively does not exist; it has an id, but is not participating in the ECS. This is different from a location in the empty archetype, which is participating (queryable, etc) but just happens to have no components.

UniqueEntityArray

An array that contains only unique Entity.

UniqueEntitySlice

A slice that contains only unique Entity.

UniqueEntityVec

A Vec that contains only unique Entity.

Derive Macros

MapEntities

Implement the MapEntities trait.