In a smoke, or fire, domain I've created light balls that are not balls emitting light, but moving planes with round colour gradients, as this gives me a smoother colour effect. What I notice is that when these light balls/planes move inside the domain, then suddenly edgy shadows appear over them, spoilinhg the effect. I enlarged one such plane to see a reference what part of the domain is casting this shadow, but I'm not sure it even is a shadow at all. But what else? But more important... How can I get rid of it?

edgy shadows

Thank you. There is indeed transparency involved, and yes it's in cycles. I've tried this, see screenshot, but it didn't affectenter image description here the shadow-effect. I've added the node setup of the blue plane, which I copied from someone who solved his lightning problem by using an array of planes. I don't think this caused the shadows, but... I'm not pro :-).

  • $\begingroup$ The second image looks exactly like the first one. Isn't there a link error? $\endgroup$
    – Jag JB
    Jul 30, 2022 at 10:34

1 Answer 1


New test:

I tried a configuration similar to yours and found that my first answer might apply when you have a lot of "light balls" superimposed.

enter image description here

I also figured out what might be the issue : when you have coplanar light balls, it might create a black zone although it should be transparent. A displacement modifier with a musgrave texture and very low scale fixes the issue as it removes any coplanarity:

without displacement

with displacement

(Outdated part but left for understanding)

When you say "moving planes with round colour gradients", do you imply that there is some transparency involved? And are you in Cycle rendering?

In that case it could mean that you are lacking some Transparent bounces in the Light path panel.

Light panel

  • $\begingroup$ Hi, thank you. Yes I was using cycles rendering, and yes, transparency is involved, but I may have handled this the wrong way. Meanwhile I have found a way to overcome the problem by firstly changing the square planes to rounds ones (so the shadows became smaller and more natural), and secondly by positioning them sp that the shadows don't spoil the camera view. But your solutions is much beter as it seems you have really understood and tacikled the problem here. Thanks a lot! $\endgroup$
    – AkaijaArt
    Aug 1, 2022 at 7:42
  • $\begingroup$ @AkaijaArt Thanks for letting us know and glad you fixed it. So maybe could you edit the title to reflect it's linked to "transparent textures casting shadow" and not shadow in smoke domain, and label the issue as resolved? $\endgroup$
    – Jag JB
    Aug 1, 2022 at 11:11

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