[Solved] Pre-UE5.5 GPU Ribbon link glitch

Technical & Engine Help Unreal Engine Help
#1

Edit 2023 0924: Got the reply from kmstu of Epic that “the ribbons linking to one another is scheduled for 5.4 fix”.
Edit 2024 0915: Bug fix to be shipped in UE 5.5.

Just noticed a GPU ribbon glitch which is reproducible in both UE 5.1 and 5.2. I wonder if anyone knows any solution or has already reported to Epic.

If a ribbon has only 1 particle left, there is some good chance that it will link to another ribbon, even though their RibbonIDs differ. I tested it in 2 circumstances: a) one single ribbon emitter which handles the RibbonID separation by itself; b) a child ribbon emitter reads the parent emitter particle position via Particle Attribute Reader.

It doesn’t matter how high or how low the spawn rate is.

“Requires Persistent IDs” is enabled in the PAR setup to correctly write RibbonID, but it is not required in the single emitter setup and does not improve the result.

Setting zero RibbonWidth or color alpha by the end of Particles.NormalizedAge can hide the glitch but it doesn’t fix the fundamental issue.

CPU ribbon doesn’t seem to suffer this issue at all.

3 Likes
Niagara ribbons hair
#2

I saw this recently as well, nice to know it is scheduled to be fixed.

#3

hi I confronted same bug, and since I cant wait for a 5.4 UE I did a little hack, and It helped me with those render artifacts so I thought that I will share. I caped opacity of 1st Vertex of a ribbon with dot product of TexCoord[0] in material and changed UVMode in RibbonRenderer to be uniform.

I dont know why setting Particle color or ribbon widith didnt help in my case, but fighting this thing was really a pain, glad it will be fixed soon

#4

As far as I can tell, this still isn’t fixed in 5.4.1

Can anyone else confirm that?

#5

Hmm, I haven’t seen it lately, but I also never saw any patch notes that mentioned this being fixed, so might still be there.

Looks like it’s probably quite a challenging issue to fix