GPU Particles2D Visual Artifacts when changing Scale + Lifetime together

[bubblemilktea-star]

Godot version

Godot 4 RC1

System information

Windows 11, RTX 3090TI

Issue description

When using GPUParticles2D and modifying the scale and timescale, it will cause the particle to streak unpredictably at the end of its lifespan.
It looks as expected in the editor, but when the app starts the bug appears.
FWIW I've noticed this bug since at least Godot 4 Beta 16. I cant speak for versions before that however.

node_2d.tscn.-.Particles-Scale-Reproduction.-.Godot.Engine.2023-02-08.13-12-12.mp4

Particles-Scale-Reproduction.DEBUG.2023-02-08.13-12-39.mp4

Steps to reproduce

1. Use a project with mode: canvas_items
2. Create a GPUParticles2D with a ParticleProcessMaterial
3. Go to Scale and use a CurveTexture and set it to 1 -> 0.5
4. Go to Time and set the Lifetime to 1.3s
5. Start the game

Minimal reproduction project

https://github.com/bubblemilktea-star/godot4-particle-scale-bug

[Calinou]

Related to #59072.

Can you reproduce this after disabling Interpolation in GPUParticles2D then setting Fixed FPS to 0?

[bubblemilktea-star]

@Calinou After disabling interpolation & setting fixed FPS to 0, the bug can still be observed.

[greycheeked]

This should be helpful: as soon as you save the CurveTexture (Scale) and run it again, no more stripes appear.
(Godot 4.1.1)