47 lines
1.3 KiB
Rust
47 lines
1.3 KiB
Rust
use crate::components::Children;
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use bevy_ecs::{Entity, Query};
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pub fn run_on_hierarchy<T, S>(
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children_query: &Query<&Children>,
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state: &mut S,
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entity: Entity,
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parent_result: Option<&mut T>,
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mut previous_result: Option<T>,
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run: &mut dyn FnMut(&mut S, Entity, Option<&mut T>, Option<T>) -> Option<T>,
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) -> Option<T>
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where
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T: Clone,
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{
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// TODO: not a huge fan of this pattern. are there ways to do recursive updates in legion without allocations?
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// TODO: the problem above might be resolvable with world splitting
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let children = match children_query.get::<Children>(entity) {
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Ok(children) => Some(
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children
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.0
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.iter()
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.map(|entity| *entity)
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.collect::<Vec<Entity>>(),
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),
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Err(_) => None,
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};
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let mut parent_result = run(state, entity, parent_result, previous_result);
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previous_result = None;
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if let Some(children) = children {
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for child in children {
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previous_result = run_on_hierarchy(
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children_query,
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state,
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child,
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parent_result.as_mut(),
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previous_result,
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run,
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);
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}
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} else {
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previous_result = parent_result;
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}
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previous_result
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}
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