Adding tweens on already spawned entities with bevy_tweening

[winter harbor]

Did anyone have any luck finding out how to do that?
In my case, whenever I add a tween to an already spawned entity, it does not work/animate.
The current way I get around this is by creating a new entity that is a copy of the previous one and inserting the tween to it.

[marsh patrol]

I'have never had issues with that. Spawning a new animator just replaces the old component with a new tween.

[winter harbor]

Oh, I don't actually spawn them with the animator component at first, I just add it later, when I need an animation (They spawn without an animation)

[marsh patrol]

how do you tween then?
IIRC only Animator<T> is a component and Tweenable is just data that the animator takes ownership over

Or you just meant the entities don't start with a tween/animator?
That should be fine - adding a tween is just inserting an animator.

[winter harbor]

Yeah, I mean the entity does not start with the animator component

Weird that it only works if I create a new entity, but doesn't if I add it during runtime

[marsh patrol]

do you have a code snipped of what works vs what doesn't?

[winter harbor]

yeah, I'm going to share it with you when I have a moment!

    mut commands: Commands,
    asset_server: ResMut<AssetServer>,
    mut health_entity: Query<(Entity, &mut Health, &mut Sprite, &Transform)>,
) {
    for (entity, health, sprite, transform) in &mut health_entity {
        if health.current_health < 0 {

            let mut tween = alpha_tween(1.0, sprite.color);
            let tween2 = scale_tween(
                    1.0,
                    Vec3::new(1.0, 1.0, 1.0),
                    Vec3::new(2.0, 2.0, 1.0),
                );

            tween.set_completed_event(0);

            commands.entity(entity).despawn();
                commands.spawn_bundle(SpriteBundle {
                    texture: asset_server.load("imgs/dish.png"),
                    transform: Transform::from_xyz(transform.translation.x, transform.translation.y, 0.),
                    ..default()
                })
                .insert(Animator::new(tween))
                .insert(Animator::new(tween2));
        }
    }
}```

so this is the code that works

where I despawn the previous entity and spawn a new one in its place (perhaps there is a better way to copy its properties to the new one)

and the animation plays as expected

this however will not work

fn health(
    mut commands: Commands,
    asset_server: ResMut<AssetServer>,
    mut health_entity: Query<(Entity, &mut Health, &mut Sprite, &Transform)>,
) {
    for (entity, health, sprite, transform) in &mut health_entity {
        if health.current_health < 0 {

            let mut tween = alpha_tween(1.0, sprite.color);
            let tween2 = scale_tween(
                    1.0,
                    Vec3::new(1.0, 1.0, 1.0),
                    Vec3::new(2.0, 2.0, 1.0),
                );

            tween.set_completed_event(0);

                commands.entity(entity).remove::<Movement>()
                .insert(Animator::new(tween))
                .insert(Animator::new(tween2));
        }
    }
}

where I just try to insert the animator components

to the queried entity

[winter harbor]

what do you think might be causing this?

[marsh patrol]

that insert code looks fine to me

I'd try inspecting the entity with smt. like bevy-inspector-egui, if the animator is really not spawned at all

dumb question - are you sure the query matches those entities?
Though it looks the same as the snippet above, so it probably does

btw. is that bevy main? IIRC don't think 0.8 queries implement IntoIterator

Sorry I couldn't help

Maybe the crate author can spot smt?
@brazen storm

[winter harbor]

Thanks for trying, it does match the entities because the 'Movement' component is successfully removed and when I do the workaround, the entity queried is correctly destroyed

It is bevy main

I didn't know the author was around here ^^, maybe!!

[marsh patrol]

would still check with the inspector though - the animator might get inserted, it just might be tweening to smt. else than expected

[brazen storm]

Are you inserting Animator<T> twice on the same entity?!

There's only a handful of reason why animation wouldn't work:

• you use a non-built-in Lens and didn't add the proper animation system; in that case your first example wouldn't work either though
• you're trying to add Animator<T> twice; I expect Bevy will not let you do that, but who knows... better check with bevy-inspector-egui

Otherwise what I do is leave the Animator<T> but re-set its tweenable:

if changed {
    // Animate cursor
    let cursor_tween = Tween::new(
        EaseFunction::QuadraticInOut,
        TweeningType::Once,
        Duration::from_millis(100),
        UiPositionLens {
            start: UiRect {
                left: Val::Px(0.0),
                top: Val::Px(50.0 * old_index as f32),
                ..default()
            },
            end: UiRect {
                left: Val::Px(0.0),
                top: Val::Px(50.0 * cursor.index as f32),
                ..default()
            },
        },
    );
    animator.set_tweenable(cursor_tween);
    animator.rewind();
    animator.state = AnimatorState::Playing;
}

Maybe you're missing a rewind() or starting again the playback with state = AnimatorState::Playing (because the animator would have stopped at the end of the previous tween)?

Technically I think the rewind() is not needed here but I don't remember for sure.

[marsh patrol]

Seemingly one is a Transform tween and the other a Sprite tween, so those animate different components and 2 animators make sense there, right?

[winter harbor]

Yeah lol, I tried to do tracks for this, but it kept telling me I couldn't insert two tracks of different types, or perhaps I didn't understand the debugger well enough

I used a sprite lens and transform lens

the built in ones

adding the two animators did work because they are of a different lens type

it works when I use them on the first object, for example

but I think you're right about the rewind

perhaps the animator component I place on an existing entity thinks it has already 'played' the tween

due to lifetime

time passed

or whatever

[brazen storm]

I meant you insert an Animator<Transform> and an Animator<Sprite> each time the system runs

[winter harbor]

maybe I should just implant a paused animator

[brazen storm]

That's unnecessary and probably wrong

[winter harbor]

oh true, that's my bad

[brazen storm]

Keep your animators paused when not in use, and set a new Tween on them when you want to use them

(and unpause them)

[winter harbor]

that's what i'll do, thanks djee, pocket cat

I think this might solve the issue

[brazen storm]

👍

[marsh patrol]

oh, right, the anim is spawned every frame

[brazen storm]

Tween<Transform> and an Tween<Sprite> are different types. You can't mix them into a same Tracks<T> (because what would T be?!)

[winter harbor]

I don't think the entity is queried twice though, so I don't think it is spawned every frame

oh actually it is, because I don't remove the queried

component

I need to remove that

to make it stop

[brazen storm]

yup

[winter harbor]

I removed the wrong one

i'll try it next and will let you know

and mark the issue as solved

that fixed it, removing the health component

so that the same entity isn't queried more than one time once it lost its health

thanks again, for the help, appreciate it a lot