Instantiating GPUParticle2D nodes with a Line2D node on screen creates graphical artifacts

[Lemonymous]

Godot version

4.0.dev (30800d2)

System information

Windows 10, Forward+, NVIDIA GeForce GTX 1050 Ti (31.0.15.1694)

Issue description

Updating a Line2D node and creating/freeing GPUParticleEmitter2D nodes will cause graphical artifacts on Godot 4. The same test project built in Godot 3.5.1.stable does not create any artifacts.

Steps to reproduce

• Create a Line2D with 2 points
• Make one of its points follow the mouse cursor
• Create a GPUParticle2D with a script freeing it when a Timer times out
• Instance GPUParticle2D nodes at the cursor location when holding down the mouse button
• Artifacts will appear when creating particles and moving the line around

Minimal reproduction project

Project created in Godot 4 - this one will show artifacts
GPU Particle Bug Godot 4.zip

The same project without created in Godot 3 - showing no artifacts
GPU Particle Bug Godot 3.zip

[Calinou]

Related to #56691.

[Lemonymous]

On v4.0.beta.custom_build [291add3] after merged PR #70418,
the graphical artifacts produced in the minimal reproduction project in this Issue seems to no longer be an issue.

However, this code in the minimal reproduction project produces a whole wall of errors now, which it did not before. I have not investigated further.

extends Node2D

const EFFECT = preload("res://gpu_particles_2d.tscn")

func _input(event):
	if event.is_action_pressed("create_effect"):
		var effect = EFFECT.instantiate()
		add_child(effect)
		effect.position = get_global_mouse_position()

Errors:

[akien-mga]

Fixed by #70418, errors are tracked in #70431.