Crate entity_data

A container for entity component data.

An entity is an opaque identifier for an object. Each entity can have multiple components associated with it. Storage is based on ECS technique, but the main purpose is to efficiently store and access individual components without Boxing them.

The approach used in this library is superior to Rust’s dynamic dispatch because components can have their separate fields and components of the same type are stored in a contiguous vector.

Examples

use entity_data::EntityStorageLayout;
use entity_data::EntityStorage;
use entity_data::entity_state;

struct Barks {
    bark_sound: String,
}

impl Barks {
    fn bark(&self) {
        println!("{}", self.bark_sound);
    }
}

#[derive(Clone)]
struct Eats {
    eaten_food: Vec<String>,
}

impl Eats {
    fn eat(&mut self, food: String) {
        self.eaten_food.push(food);
    }
}

struct Dog {
    favorite_food: String,
}

struct Bird {
    weight: f32,
    habitat: String,
}

fn main() {
    let mut layout = EntityStorageLayout::new();
    let type_dog = layout.add_archetype().with::<Dog>().with::<Barks>().with::<Eats>().build();
    let type_bird = layout.add_archetype().with::<Bird>().with::<Eats>().build();

    let mut storage = EntityStorage::new(&layout);

    let eats = Eats { eaten_food: vec![] };

    let super_dog = storage.add_entity(type_dog, entity_state!(
        Dog = Dog { favorite_food: "meat".to_string(), },
        Eats = eats.clone(),
        Barks = Barks { bark_sound: "bark.ogg".to_string() },
    ));

    let hummingbird = storage.add_entity(type_bird, entity_state!(
        Bird = Bird { weight: 0.07, habitat: "gardens".to_string() },
        Eats = eats
    ));


    let super_dog_barks = storage.get::<Barks>(&super_dog).unwrap();
    super_dog_barks.bark();

    let super_dog_props = storage.get_mut::<Dog>(&super_dog).unwrap();
    super_dog_props.favorite_food = "beans".to_string();

    let hummingbird_eats = storage.get_mut::<Eats>(&hummingbird).unwrap();
    hummingbird_eats.eat("seeds".to_string());
}

Macros

__replace_expr

add_archetype

A simple method of adding a archetype to EntityStorageLayout.

entity_state

Structs

ArchetypeBuilder

An archetype builder.

ComponentInfo

EntityId

An entity identifier.

EntityState

An entity state comprising of different components.

EntityStorage

A container of entities.

EntityStorageLayout

A layout of the EntityStorage. Can be used to crate multiple EntityStorages with the same archetypes.