XECS
An Entity-Component-System library
Simple Example
// Define two components struct
// Component is Send + Sync + 'static
;
;
// create an empty world
let mut world = new;
// generate 10 entities
for _ in 0..10
// print all postions
for pos in world.
// filter some entities need to be hidden
let ids = world.
.with_id
.filter
.map
.;
// attach hidden to id
for id in ids
// make a full-owning group to accelerate the query
world.make_group;
// only print postions with id that is not hidden
for in world.
About entity
Entity in XECS is just an number ID.In XECS, it's just a
NonZeroUsize.
The ID is allocated from 1 by world automatically. The id=0
represents a recycled ID without any other flags through Option<EntityId>
.
ID recycling
When you call world.create_entity()
, an ID will be allocated automatically.
If you call world.remove_entity(id)
, this ID will be a pit. If the
next world.create_entity()
is called, it will allocate this ID to fill
the pit.Thanks to sparse set, it's still fast to
iterate all components no matter how random of ID
Concurrency Safety
Because Component is just T : Send + Sync
.
World can use RwLock to
ensure the borrow check relations of all components.And World can also
be Send + Sync
.Therefore,the all other states of world can be guarded
by RwLock.So we can use world in concurrency environment by RwLock<World>
.
System in XECS
System is a Stream with World as Context. Because Stream is not stable in std, XECS use futures::Stream instead.
To Run System
Because system is just an async trait, you need a wrapper of runtime from tokio or async-std