It only happens occasionally so it’s hard for me to reproduce, so I can only generally ask what the reason for something like this could be.
My Niagara Smoke Pillars are sometimes flickering heavily, all at the same time. It seems the more there are, the higher the chance they will flicker.
I am doing something in the material, to fade out opacity as you approach the campfire (like in lego fortnite). Is there maybe generally something wrong about my material? (attached image)
Problem:
I managed to reproduce it without any opacity logic, so it can’t be that. It happens more frequently when I equip a torch (which spawns a point light), and it stops if I use Forward Shading on the smoke material. however this is probably not a good solution since it’s more expensive and also looks different…
it seems like when there are point lights in the scene, the particles cannot decide whether to be lit or unlit. it switches between these two states:[Image Removed][Image Removed]the darker version is how it should look
Hi there,
This does look like there is some sort of fighting over which lights should affect the smoke here. I wonder if it might be related to a similar issue I am assigned to [Content removed] Would you be able to create minimal a reproduction project that reproduces this issue and link it here. I have not been able to reproduce the flickering issue in the other project, so it would be good to get a reproduction of this.
Regards,
Lance Chaney
Hello Lance, thanks for looking into this. Unfortunately I cannot open the link to the other issue, probably I don’t have access.
It is really hard to reproduce in a fresh project but I will keep trying!
I don’t think it is switching between lights affecting the smoke, but rather making it completely unlit. None of our point lights would be that bright to make the smoke all white.
Apologies, I’ve updated the link to the public link which you should have access to (link again [Content removed] Would you be able to send through a project with the same Niagara smoke system and material setup? Even if you can’t reproduce the issue, this would be a helpful first step for me to see if I can reproduce it on my end.
Regards,
Lance Chaney
Hello Lance, thanks for your reply!
Here is a project with our smoke and similar lighting (night time and a point light).
At the very least the flickering appears shortly when opening the level. We would very much appreciate if you could look into it.
Best regards,
Matthias
Thanks for project. To clarify, should this project reproduce the issue? Or is it just the Niagara systems + material and basic lighting setup? I haven’t been able to reproduce the flickering on my end so far.
Just to double check, are you on version 5.6.0 or 5.6.1 of the Engine? And are you on a launcher version? or building from source? If source, what CL are you on?
From some brief debugging, I’m guessing the flickering is possibly caused by the sky atmosphere shadowing / attenuation not applying to the translucent smoke material. The sky atmosphere is what is attenuating the directional light when the directional light angle is passed the horizon. This might show up as flickering if you are at the edges of the translucent lighting volume. As a quick test, could you try increasing r.TranslucencyLightingVolumeOuterDistance from its current value (default 5000, try doubling) when you are getting the flickering issue to see if this resolves the issue at that specific distance. Then the next step will be figuring out why the attenuation isn’t applying, or is flicking on/off.
Regards,
Lance Chaney