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use super::Node;
use bevy_ecs::{Entity, Query, With, Without};
use bevy_transform::{
hierarchy,
prelude::{Children, Parent, Transform},
};
pub const UI_Z_STEP: f32 = 0.001;
pub fn ui_z_system(
mut root_node_query: Query<With<Node, Without<Parent, Entity>>>,
mut node_query: Query<(Entity, &Node, &mut Transform)>,
children_query: Query<&Children>,
) {
let mut current_global_z = 0.0;
let root_nodes = (&mut root_node_query.iter())
.iter()
.collect::<Vec<Entity>>();
for entity in root_nodes {
if let Some(result) = hierarchy::run_on_hierarchy(
&children_query,
&mut node_query,
entity,
Some(current_global_z),
Some(current_global_z),
&mut update_node_entity,
) {
current_global_z = result;
}
}
}
fn update_node_entity(
node_query: &mut Query<(Entity, &Node, &mut Transform)>,
entity: Entity,
parent_result: Option<f32>,
previous_result: Option<f32>,
) -> Option<f32> {
let mut z = UI_Z_STEP;
let parent_global_z = parent_result.unwrap();
if let Some(previous_global_z) = previous_result {
z += previous_global_z - parent_global_z;
};
let global_z = z + parent_global_z;
let mut transform = node_query.get_mut::<Transform>(entity).ok()?;
transform.translation_mut().set_z(z);
Some(global_z)
}