Struct bevy::prelude::Changed

pub struct Changed<T>(_);

Filter that retrieves components of type T that have been changed since the last execution of this system

This filter is useful for synchronizing components, and as a performance optimization as it means that the query contains fewer items for a system to iterate over.

Because the ordering of systems can change and this filter is only effective on changes before the query executes you need to use explicit dependency ordering or ordered stages to avoid frame delays.

Example:

fn print_moving_objects_system(query: Query<&Name, Changed<Transform>>) {
    for name in query.iter() {
        println!("Entity Moved: {:?}", name);
    }
}

Trait Implementations

impl<T> WorldQuery for Changed<T> where
    T: Component, 

type Fetch = ChangedFetch<T>

type State = ChangedState<T>