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use crate::prelude::{Children, Parent, PreviousParent};
use bevy_ecs::{Component, DynamicBundle, Entity, WorldBuilder};
pub struct WorldChildBuilder<'a, 'b> {
world_builder: &'b mut WorldBuilder<'a>,
parent_entities: Vec<Entity>,
}
impl<'a, 'b> WorldChildBuilder<'a, 'b> {
pub fn spawn(&mut self, components: impl DynamicBundle + Send + Sync + 'static) -> &mut Self {
let parent_entity = self
.parent_entities
.last()
.cloned()
.expect("There should always be a parent at this point.");
self.world_builder
.spawn(components)
.with_bundle((Parent(parent_entity), PreviousParent(Some(parent_entity))));
let entity = self.world_builder.current_entity.unwrap();
{
let world = &mut self.world_builder.world;
let mut added = false;
if let Ok(mut children) = world.get_mut::<Children>(parent_entity) {
children.push(entity);
added = true;
}
if !added {
world
.insert_one(parent_entity, Children(smallvec::smallvec![entity]))
.unwrap();
}
}
self
}
pub fn with_bundle(
&mut self,
components: impl DynamicBundle + Send + Sync + 'static,
) -> &mut Self {
self.world_builder.with_bundle(components);
self
}
pub fn with(&mut self, component: impl Component) -> &mut Self {
self.world_builder.with(component);
self
}
}
pub trait BuildWorldChildren {
fn with_children(&mut self, spawn_children: impl FnMut(&mut WorldChildBuilder)) -> &mut Self;
}
impl<'a> BuildWorldChildren for WorldBuilder<'a> {
fn with_children(
&mut self,
mut spawn_children: impl FnMut(&mut WorldChildBuilder),
) -> &mut Self {
{
let current_entity = self.current_entity.expect("Cannot add children because the 'current entity' is not set. You should spawn an entity first.");
let mut builder = WorldChildBuilder {
world_builder: self,
parent_entities: vec![current_entity],
};
spawn_children(&mut builder);
}
self
}
}
impl<'a, 'b> BuildWorldChildren for WorldChildBuilder<'a, 'b> {
fn with_children(
&mut self,
mut spawn_children: impl FnMut(&mut WorldChildBuilder),
) -> &mut Self {
let current_entity = self
.world_builder
.current_entity
.expect("Cannot add children without a parent. Try creating an entity first.");
self.parent_entities.push(current_entity);
self.world_builder.current_entity = None;
spawn_children(self);
self.world_builder.current_entity = self.parent_entities.pop();
self
}
}