Closed
Description
Bevy version
0.9
308e092
What you did
I ran the following snippet of code
use bevy::prelude::*;
fn main() {
App::new()
// We need a game loop for the problem to occur.
.add_plugins(DefaultPlugins)
// spawn some entities
.insert_resource(MyEntities::default())
.add_startup_system(spawn_entities)
.add_system(query_system)
.run();
}
#[derive(Default, Resource)]
struct MyEntities(Vec<Entity>);
#[derive(Debug, Component, PartialEq, Eq)]
struct IndexComponent(i32); // we use this component to check that we have the correct component
#[derive(Component)]
#[component(storage = "SparseSet")]
struct MySparseComponent;
fn spawn_entities(mut commands: Commands, mut my_entities: ResMut<MyEntities>) {
(0..10)
.for_each(|i|
// spawn an entity, give it an `IndexComponent` with its number, and push it into `MyEntities`
my_entities.0.push(commands.spawn(IndexComponent(i)).id())
);
}
fn query_system(
mut commands: Commands,
my_entities: Res<MyEntities>,
query: Query<&IndexComponent>,
mut frame_counter: Local<usize>,
) {
let mut last: Option<Entity> = None;
for &entity in my_entities.0.iter() {
let get = query.get(entity).unwrap();
let get_comp = query.get_component::<IndexComponent>(entity).unwrap();
// give the entity the sparse component
commands.entity(entity)
.insert(MySparseComponent);
// remove the sparse component from the last entity
if let Some(last) = last {
commands.entity(last)
.remove::<MySparseComponent>();
}
// this is where things go wrong
if get != get_comp {
dbg!(entity, get, get_comp);
dbg!(*frame_counter);
panic!("AAAA");
}
last = Some(entity);
}
// count what frame we are on
*frame_counter += 1;
}What went wrong
Here, get and get_comp should have the same value, which they do on the first frame, but not on the second.
Additional information
In this example MyEntities and IndexcComponent are just some scaffolding in order to demonstrate the problem. What is important is MySparseComponent and the fact that it is of storage type SparseSet.
I made a git repo containing this snippet for convenience.