Check if input marked handled before processing additional CollisionObjects

[madmiraal]

Currently, when processing picking, all CollisionObject2Ds under the mouse pointer are processed regardless of whether or not set_input_as_handled() was called. This PR checks whether set_input_as_handled() has been called before processing additional CollisionObject2Ds.

Fixes #48788

[jeremyz]

you can't do this as Area2d's processing order is not determined see #23051

[madmiraal]

@jeremyz This change doesn't affect any potential fix to #23051. The order in which they are processed doesn't change the need to not do further processing if one of them marks the event as handled.

[jeremyz]

@madmiraal sure, but this will change the status of a call to set_input_as_handled() from ignored to unreliable.
Without a predetermined processing order, it just adds confusion. (my thoughts).

[ajreckof]

I think personally that this is still the right fix for this bug. The bug is that the call to set_input_as_handled() is ignored. The fact that it is randomly taken is it's own other bug which need an other fix i don't see any reason as to why not get this fix put right as if you don't want to be handled randomly you can just not set the input as handled.

[Sauermann]

This approach is going to introduce a bug, because Physics Picking can happen in a later frame than the frame in which the event was created.

Here is a MRP, that shows this problem: BugPhysicsSetHandled.zip

extends Area2D

func _unhandled_input(event):
	if (randi_range(0, 1) == 0):
		get_viewport().set_input_as_handled()

func _on_input_event(viewport, event, shape_idx):
	if (get_viewport().is_input_handled()):
		print("ERROR")

The following happens:
Frame 1:

• no call to set_input_as_handled() happens
• The event is stored for asynchronous physics picking

Frame 2:

• set_input_as_handled() is called during _unhandled_input()
• The physics-picking event of Frame 1 is now processed and gets the information, that the event has been handled, even though it wasn't set to handled in Frame 1.

This PR would require, that during the evaluation of physics picking the event-handled-status of a previous frame would need to be available, but it isn't.

[madmiraal]

@Sauermann The bug you describe is not introduced by this PR. It happens with beta 17 too. Therefore, it is a pre-existing bug that needs it's own issue.

[Sauermann]

Because of the described behavior, this PR will introduce the problem, that sometimes InputEvents will be discarded for Physics-Picking, while they are expected to be used for Physics-Picking. So this PR depends on the described behavior to be changed.

[madmiraal]

As per the documentation, physics _input_event() is called after _unhandled_input(); so marking an event as handled in _unhandled_input() should prevent it being processed by _input_event().

[Sauermann]

Approved in PR-review meeting

[akien-mga]

Could you rebase for good measure? There doesn't seem to be conflicts but since the commit is now 2 years old, it's probably good to make sure it still passes CI and tests.

[Sauermann]

The problem, that I wrote about in my previous message #48800 (comment) has been solved in #79546.

[akien-mga]

Thanks!