Even Roblox Has Max Trail Length… Why Don’t Unreal and Unity?

[Dimi]

I’ve been playing around with Roblox VFX tools, and there’s this super simple thing in their Trail component – Max Length. You literally clamp the trail length. Done.

Why the hell don’t we have this out-of-the-box in Unreal or Unity?

I had a real production case with Niagara: I had ribbons attached to a character. In one specific animation, the character was moving insanely fast, and the ribbons turned into full-on spaghetti, insanely long and messy. Looked terrible.

The only control I had was lifetime.
So I reduced it to something like ~0.1s. And yeah – it fixed that one fast animation. But then everything else broke. In slower animations, the trail became way too short, unusable.

In Roblox
Lifetime ≠ Max Length. These are different controls.

Lifetime is time-based.
Max Length is space-based.

3 examples:
A) Lifetime = 0.125 | Max Length = 200

B) Lifetime = 0.125 | Max Length = 5

C) Lifetime = 0.5 | Max Length = 5

In Roblox – you get both.
In Unreal/Unity – you’re stuck with the “lifetime” parameter

How are you guys handling this in Unreal?
Is there a clean Niagara setup for clamping trail length?
Maybe someone has a neat scratchpad module or script to share?

Сheers guys.

[MascoFX]

Hi,

I didn’t try it yet but I found this breakdown some months ago showing a scratch pad that is working amazingly well

- YouTube

[yeray_art]

Hi here’s my solution!

You could calculate the distance between your current and previous simulation position on a system level:

And then in particle update accumulate that distance to sort of replicate the ribbon length. Then you can compare it to a max length parameter and kill the particles if they’re too long:

[ifurkend]

Sorry for being late to the thread:
There is the Emitter.DistanceTraveled parameter from Emitter State module doing the same thing of accumulating actor position delta distance.