Aery
A plugin that adds a subset of Entity Relationship features to Bevy using Non-fragmenting
ZST relations.
Currently supported:
- ZST relations
- Fragmenting on (relation) type
- Cleanup policies
- Declarative APIs for:
- Joining
- Traversing
- Spawning
API tour:
Non exhaustive. Covers most common parts.
```rust
use bevy::prelude::;
use aery::prelude::;
fn main() {
App::new()
.addplugins(Aery)
.addsystems(Startup, setup)
.add_systems(Update, (alert, sys))
.run();
}
[derive(Component)]
struct Foo;
[derive(Component)]
struct Bar;
[derive(Relation)]
[cleanup(policy = "Recursive")]
struct ChildOf;
[derive(Relation)]
[multi]
struct Bag;
// Spawning entities with relations
fn setup(mut commands: Commands) {
// A hierarchy of Foos with (chocolate? OwO) Bars in their Bags
commands.add(|wrld: &mut World| {
wrld.spawn(Foo)
.scope::(|, mut child| {
child.insert(Foo);
child.scopetarget::(|, mut bag| { bag.insert(Bar); });
})
.scope::(|, mut child| {
child.insert(Foo);
child.scopetarget::(|, mut bag| { bag.insert(Bar); });
});
})
}
// Listening for relation events
fn alert(mut events: EventReader) {
for event in events.iter() {
if event.matches(Wc, TargetOp::Set, ChildOf, Wc) {
println!("{:?} was added as a child of {:?}", event.host, event.target);
}
}
}
// Relation Queries
fn sys(
foos: Query<(&Foo, Relations<(Bag, ChildOf)>)>,
roots: Query>,
bars: Query<&Bar>,
) {
foos.ops()
.join::(&bars)
.traverse::(roots.iter())
.foreach(|fooparent, foo, bar| {
// ..
})
}
```
Version table
| Bevy version | Aery verison |
|--------------|--------------|
| 0.11 | 0.3 |
| 0.10 | 0.1 - 0.2 |
Credits
- Sander Mertens:
Responsible for pioneering Entity Relationships in ECS and the author of Flecs which Aery has taken
a lot of inspiration from.