classes/class_tween

[giscus[bot]]

classes/class_tween

Inherits: RefCounted< Object Lightweight object used for general-purpose animation via script, using Tweener s. Description: Tweens are mostly useful for animations requiring a numerical property t...

https://docs.godotengine.org/en/stable/classes/class_tween.html

[JakeCC-Codes]

When tweening methods, unlike the "look_at()" method, that use callables that bind to the first argument. A workaround may be used:

var following_node = self
var starting_position = following_node.global_position
var tween = create_tween()
tween.tween_method(func(i): following_node.global_position = starting_position.lerp(target_node.global_position, i), 0.0, 1.0, 5.0) # This function follows a target node for 5 seconds

[Selus]

Why do you need a 'workaround'?

[bjordan2010]

I am trying to tween a ColorRect's alpha property using:

tween.tween_property(fader, "color:a", 0.0, 1.0).from(1.0)

I get an error, "Cannot call method 'from' on a null value."

The full function is:

func fade_in() -> void:
	var tween = create_tween()
	tween.tween_interval(0.1)
	tween.tween_property(fader, "color:a", 0.0, 1.0).from(1.0)

The fader is an onready node variable. This worked in 4.2.2 so I'm guessing something changed and "color:a" no longer works so it returns a null?

[bjordan2010]

I figured it out. I removed the containing scene from the project settings autoload and added it back. Suddenly, this code started working. Perhaps the scene was added to autoload before the child fader was added to the scene or something was wrong with the parent child relationship in the scene. I'm not sure, but it's working now.

[gapthemind101]

I'm finding that this construction:

if tween:
	tween.kill() # Abort the previous animation.
tween = create_tween()

in the case that the tween exists, even if new and untasked, the tween won't animate (or not right away at least; I didn't have the patience to wait). Taking out the kill part and just creating a new tween for every new thing to do, seems to work always.

[bjordan2010]

No previous existing tween, and still getting error.

[gapthemind101]

hey hey. I was writing that in response to the general docs. however I do recall having that problem.. I just looked at my code, and I remember the problem was that tween_property was returning NULL, so my follow-on call (in your case from() ) was trying to operate on null. You probably already saw that. I fixed it when I switched from having a tween I tried to reuse, to just creating a new tween for every new animation. even trying to tell the tween to die caused a no-animation problem.

I see your code creates the tween anew each time, so that may not be the problem at all, but maybe it's a direction to look at.

[nielsvaes]

In the code snippet for tween_method, is the use of .bind correct here?

var tween = create_tween()
tween.tween_method(look_at.bind(Vector3.UP), Vector3(-1, 0, -1), Vector3(1, 0, -1), 1) 

# The look_at() method takes up vector as second argument.

Shouldn't it be this?

tween.tween_method(look_at.bind(null, Vector3.UP), Vector3(-1, 0, -1), Vector3(1, 0, -1), 1) 

Since otherwise we'd be binding Vector3.UP to target instead of up?

[onomatopoetry]

I pulled my hair out for hours trying to figure out how to use SetEase() and SetTrans() properly with C#. If you are too, hopefully this helps! The correct format for the enums these methods require as parameters is CamelCase (as is normal for C#) but with no prefix. Instead of Tween.EASE_IN_OUT (in GDScript), use Tween.EaseType.InOut in C#. So for example, the set_ease example becomes, in C#:

Tween tween = CreateTween();
tween.TweenProperty(this, "position", new Vector2(300, 0), 0.5); // Uses EASE_IN_OUT.
tween.SetEase(Tween.EaseType.In);
tween.TweenProperty(this, "rotation_degrees", 45.0, 0.5); // Uses EASE_IN.

The set_trans example becomes, in C#:

Tween tween = CreateTween();
tween.TweenProperty(this, "position", new Vector2(300, 0), 0.5); // Uses EASE_IN_OUT.
tween.SetTrans(Tween.TransitionType.Sine);
tween.tween_property(self, "rotation_degrees", 45.0, 0.5); // Uses TRANS_SINE.

[imdongye]

var tween: Tween
var id: int = 0
func _on_button_pressed() -> void:
	if tween:
		tween.kill()
	print("start")
	id += 1
	tween = create_tween()
	tween.tween_callback(func():
		print("done"+str(id))
	).set_delay(3)
	await tween.finished
	print("finished"+str(id))

Is it okay to have orphans in await if a button is pressed multiple times in 3 seconds?

[gapthemind101]

as I understand things now, a tween that's left orphan will just deallocate itself quietly and this won't cause any memory bloating. In fact I had a problem where I was creating a new tween over and over, expecting the old (orphaned) one to just run by itself, but no, it was deallocating the old tween when I overwrote the one handle to it, as if I'd killed it explicitly. This isn't made very clear in the docs, at least the ones I was reading.

So, I think you don't need to do the kill() part.

My guess is that what you have here should work even if you press the button a bunch of times. (although each time it'll leave whatever animation was going on paused where it was).

Let me know if I'm wrong, I want to see if I have a correct understanding of this thing.