Repeated use of SceneTreeTween causes an endless loop

[colorworlds]

Godot version

v3.5.stable.official [991bb6a]

System information

win7,gles3

Issue description

Repeated use of SceneTreeTween causes an endless loop.

onready var _tween:SceneTreeTween = create_tween()

# Move to the specified location according to the specified time
func move_to(_new_pos:Vector2,_time:float):

	_tween.play()

	_tween.tween_property(self, "position", 
					  _new_pos , _time)

	yield(_tween,'finished')
	_tween.stop()

func _ready():
	yield(move_to(Vector2(100,100),1),'completed') # move to (100,100)

	yield(move_to(Vector2(200,100),1),'completed') # move to (100,100) ,(200,100)
	
	# yield(move_to(Vector2(200,200),1),'completed') # move to (100,100), ( 200,100),( 200,200) 

	# _tween.play() # This line of code will lead to an endless loop ,but  the same code exists in the move_to function

I'm going to change all the Tweet codes into new SceneTreeTween, but this problem makes me feel a risk.

I'm not sure if SceneTreeTween support reuse. But for example, when I want to achieve a screen shake effect, I need to ensure that the last screen shake effect is terminated first. In this way, I must keep the last SceneTreeTween every time, and then generate a new SceneTreeTween, which is counter intuitive.

Steps to reproduce

Transformer.zip

Minimal reproduction project

No response

[KoBeWi]

I'm not sure if SceneTreeTween support reuse.

It kind of does, but not in an expected way. When you add a new Tweener, it gets added to what you already have. The animation is not reset between runs.

What happens in your example is:

• you tween to 100, 100
• you add another Tweener to the same SceneTreeTween (that have already finished)
• the SceneTreeTween executes 100, 100 and then 200, 100
• you then add yet another Tweener
• so your final sequence is 100, 100 -> 200, 100 -> 200, 200
• combined all these, you get: 100, 100 -> 100, 100 -> 200, 100 -> 100, 100 -> 200, 100 -> 200, 200
  
  I'm a bit surprised that SceneTreeTween supports this kind of reuse, but it's an expected behavior in the end.

But for example, when I want to achieve a screen shake effect, I need to ensure that the last screen shake effect is terminated first. In this way, I must keep the last SceneTreeTween every time, and then generate a new SceneTreeTween, which is counter intuitive.

Yes, this is what you should do. You should also kill the previous SceneTreeTween if you are restarting animation. This was recently clarified here: #65658
tbh the SceneTreeTween documentation page is so detailed that I'd just suggest giving it a good read. The main clue is that SceneTreeTweens aren't supposed to be reused, because there is no point in doing that.

[colorworlds]

@KoBeWi hello,The key problem is that the following line will cause the program to crash:

_tween.play()

An infinite loop indicates a program crash.
The complete code is like the following. I have asked others to test it on other computers. Crashes are bound to happen:

func _ready():
	yield(move_to(Vector2(100,100),1),'completed') # move to (100,100)

	yield(move_to(Vector2(200,100),1),'completed') # move to (100,100) ,(200,100)

	_tween.play() 

[KoBeWi]

Ah I missed it, because it was commented out in your MRP.
Crash stack trace:

CrashHandlerException: Program crashed
Engine version: Godot Engine v4.0.beta.custom_build (d1b2a191ab752ebd8236e3547e07b6eb3bb1f260)
Dumping the backtrace. Please include this when reporting the bug on: https://github.com/godotengine/godot/issues
[0] VectorWriteProxy<List<Ref<Tweener>,DefaultAllocator> >::operator[] (C:\Users\Tomek\Desktop\Godot\godot\core\templates\vector.h:52)
[1] Tween::step (C:\Users\Tomek\Desktop\Godot\godot\scene\animation\tween.cpp:298)
[2] SceneTree::process_tweens (C:\Users\Tomek\Desktop\Godot\godot\scene\main\scene_tree.cpp:560)
[3] SceneTree::process (C:\Users\Tomek\Desktop\Godot\godot\scene\main\scene_tree.cpp:479)
[4] Main::iteration (C:\Users\Tomek\Desktop\Godot\godot\main\main.cpp:3005)
[5] OS_Windows::run (C:\Users\Tomek\Desktop\Godot\godot\platform\windows\os_windows.cpp:895)
[6] widechar_main (C:\Users\Tomek\Desktop\Godot\godot\platform\windows\godot_windows.cpp:179)
[7] _main (C:\Users\Tomek\Desktop\Godot\godot\platform\windows\godot_windows.cpp:201)
[8] main (C:\Users\Tomek\Desktop\Godot\godot\platform\windows\godot_windows.cpp:215)
[9] WinMain (C:\Users\Tomek\Desktop\Godot\godot\platform\windows\godot_windows.cpp:229)
[10] __scrt_common_main_seh (d:\a01\_work\2\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288)
[11] BaseThreadInitThunk
-- END OF BACKTRACE --