pub fn parent_opacities(
main: &mut World,
parents: &HashMap<Entity, Entity>,
) -> HashMap<Entity, f32>Expand description
Returns each entity’s cumulative ANCESTOR opacity product (own
Opacity excluded - extract fns already fold that in). CSS
semantics: opacity multiplies down the subtree, so fading a dialog
root fades every descendant. Returns an empty map when no entity
carries an Opacity (the overwhelmingly common case - extracts
then skip the lookup entirely).