GPUParticles2D trails continue simulating when tree is paused

[tivec]

Godot version

v4.2.rc1.official [ad72de5]

System information

Godot v4.2.rc1 - Windows 10.0.22631 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1660 Ti (NVIDIA; 31.0.15.3699) - AMD Ryzen 7 4800H with Radeon Graphics (16 Threads)

Issue description

Particle trails continue simulating and cause weird artifacts when the game is paused. I have tested this on 4.2 Beta 6, RC1, but also on 4.1.3 stable.

godot_z8cBnfh0uH.mp4

The above video is from the MRP included below.

Steps to reproduce

• Load the included MRP project
• Start the game (main.tscn)
• Let the particles simulate for a little to see how they're supposed to be behaving.
• Press SPACE to pause the game. Wait 5-10 seconds
• Watch particles behave weirdly.
• Press SPACE to unpause the game to see even more chaos before the particle system returns to normal.

Minimal reproduction project

ParticleTrailPaused.zip

[Calinou]

• Related to Particle jitter on low speed scale, when the SceneTree is paused or when process mode is Disabled due to interpolation #50824 and Interpolate in GPUParticles makes particles stutter when paused at high FPS. #65390.

[tivec]

• Related to Particle jitter on low speed scale, when the SceneTree is paused or when process mode is Disabled due to interpolation #50824 and Interpolate in GPUParticles makes particles stutter when paused at high FPS. #65390.

I am not certain, changing the interpolation flag has no discernible effect.

[tivec]

Further testing on this has shown that it does not only happen on particles with trails, but it might be related to turbulence. I have attached a new MRP that also shows a third particle system that has trails, but has turbulence turned off.

ParticleTrailPaused.zip

So two things I can take away from this:

• Some particle simulation continues to happen when the tree is paused, if turbulence is on. This is probably unintended.
• Trails should probably stop simulating when the tree pauses.