Trait moonshine_behavior::Behavior

source ·

pub trait Behavior: Component + Debug {
    // Provided methods
    fn allows_next(&self, _next: &Self) -> bool { ... }
    fn is_resumable(&self) -> bool { ... }
}

Expand description

A Component which represents some state of its Entity.

§Usage

A Behavior is typically implemented as an enum type.

§Example

use bevy::prelude::*;
use moonshine_behavior::prelude::*;

#[derive(Component, Default, Debug, Reflect)]
#[reflect(Component)]
enum Bird {
    #[default]
    Idle,
    Fly,
    Sleep,
    Chirp,
}

use Bird::*;

impl Behavior for Bird {
    fn allows_next(&self, next: &Self) -> bool {
        match self {
            Idle => matches!(next, Sleep | Fly | Chirp),
            Fly => matches!(next, Chirp),
            Sleep | Chirp => false,
        }
    }

    fn is_resumable(&self) -> bool {
        matches!(self, Idle | Fly)
    }
}

fn spawn_bird(mut commands: Commands) {
    commands.spawn(BehaviorBundle::<Bird>::default());
}

fn chirp(mut bird: Query<BehaviorMut<Bird>>) {
    bird.single_mut().try_start(Chirp);
}

fn is_chirping_while_flying(bird: Query<BehaviorRef<Bird>>) -> bool {
    let behavior = bird.single();
    matches!(*behavior, Chirp) && matches!(behavior.previous(), Some(Fly))
}