Crate bevy_hecs

A handy ECS

hecs provides a high-performance, minimalist entity-component-system (ECS) world. It is a library, not a framework. In place of an explicit "System" abstraction, a World's entities are easily queried from regular code. Organize your application however you like!

In order of importance, hecs pursues:

• fast traversals
• a simple interface
• a small dependency closure
• exclusion of externally-implementable functionality

let mut world = World::new();
// Nearly any type can be used as a component with zero boilerplate
let a = world.spawn((123, true, "abc"));
let b = world.spawn((42, false));
// Systems can be simple for loops
for (id, mut number, &flag) in &mut world.query_mut::<(Entity, &mut i32, &bool)>() {
  if flag { *number *= 2; }
}
assert_eq!(*world.get::<i32>(a).unwrap(), 246);
assert_eq!(*world.get::<i32>(b).unwrap(), 42);

Macros

impl_query_set
smaller_tuples_too	Imagine macro parameters, but more like those Russian dolls.

Structs

Added	Query transformer that retrieves components of type T that have been added since the start of the frame.
Archetype	A collection of entities having the same component types
ArchetypeComponent
ArchetypesGeneration	Determines freshness of information derived from World::archetypes
AtomicBorrow	Atomically enforces Rust-style borrow checking at runtime
Batch	A sequence of entities yielded by BatchedIter
BatchedIter	Batched version of QueryIter
BuiltEntity	The output of an EntityBuilder, suitable for passing to World::spawn or World::insert
Changed	Query transformer that retrieves components of type T that have either been mutated or added since the start of the frame.
Entity	Lightweight unique ID of an entity
EntityBuilder	Helper for incrementally constructing a bundle of components with dynamic component types
EntityReserver	Reserves entities in a way that is usable in multi-threaded contexts.
Location	A location of an entity in an archetype
MissingComponent	Error indicating that an entity did not have a required component
Mut	Unique borrow of an entity's component
Mutated	Query transformer that retrieves components of type T that have been mutated since the start of the frame. Added components do not count as mutated.
NoSuchEntity	Error indicating that no entity with a particular ID exists
Or	Query transformer performing a logical or on a pair of queries Intended to be used on Mutated or Changed queries.
QueryIter	Iterator over the set of entities with the components in Q
Ref	Shared borrow of an entity's component
RefMut	Unique borrow of an entity's component
SpawnBatchIter	Entity IDs created by World::spawn_batch
TypeAccess	Provides information about the types a [System] reads and writes
TypeState	Metadata about a type stored in an archetype
With	Query transformer skipping entities that do not have a T component
Without	Query transformer skipping entities that have a T component
World	An unordered collection of entities, each having any number of distinctly typed components

Enums

ComponentError	Errors that arise when accessing components
QueryAccess

Traits

Bundle	A statically typed collection of components
Component	Types that can be components, implemented automatically for all Send + Sync + 'static types
DynamicBundle	A dynamically typed collection of components
Query	A collection of component types to fetch from a World
ReadOnlyFetch	A fetch that is read only. This should only be implemented for read-only fetches.

Derive Macros

Bundle

Implement Bundle for a monomorphic struct