Wednesday, December 6, 2023
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[Niagara 5.0] Repair ribbon hole Mini Tutorial

Repair ribbon hole


The intention of those mini tutorials is to have simply searchable reference for the implementation of primary concepts in Niagara.

Right now I wish to have a fast have a look at how we would clear up a typical subject when utilizing Ribbons.
Until you spawn a particle each single body, there’ll all the time be a niche between the supply of the ribbon and the ribbon itself.

Spawning a particle each body, generally is a resolution in some circumstances, but it surely’s usually higher to discover a resolution in which you’ll bridge that hole
There are just a few methods to cope with this, however I’d wish to current a reasonably primary one that may work in numerous conditions.

Primary Setup
The technique right here will probably be to reliably discover the final spawned particle and snap it to our supply location (the emitter place on this instance).
We do that by, for each particle, evaluating the index of that particle with the whole variety of particles which were spawned within the emitter. Within the case that we do have the final spawned particle, we set the Place of the particle to the simulation place.

Now to know the whole variety of particles we nonetheless have to hold monitor of that one way or the other.
To do that, we’ll alter the SpawnPerUnit and SpawnRate modules. (You’ll in all probability wish to create a replica for this.)
On the finish of the modules we will add somewhat part that reads the spawn rely and provides it to Emitter.TotalParticlesSpawned.

And growth now the final particle of your ribbon will stay connected to the supply.

Besides that’s not totally the case.
As a consequence of tick order it’s doable that this script will probably be executed earlier than the motion script of the supply.
This may create a one body hole between the final particle and the supply.
We are able to clear up this on a case by case foundation, by forcing the Niagara Tick to later within the body.
That is typically unwell suggested as a result of it takes away the engines capability to utilize threading in an environment friendly manner, but when used sparingly it may be useful.

And there you go, a fairly strong solution to make your ribbons gap-less.

Take pleasure in.


After GPU Ribbon is on the market to Niagara I’m now not too bothered with this subject, however I nonetheless wish to share a much less correct however barely simpler resolution to the hole subject when utilizing Spawn Fee.

This strategy assumes the consumer to stay with a continuing spawn price worth, as a result of there’s little or no level of randomizing the spawn price worth each body in a ribbon emitter. Anyway as a result of the spawn price worth is fixed, we will merely calculate the spawn interval in second by 1/SpawnRateValue, then in Particle Replace stage, do a Lerp Place and select between SimulationPosition and Particles.Preliminary.Place (or simply Particles.Place will depend on your use case) by checking if the Particles.Age is smaller than the spawn interval.


@ifurkend Humorous sufficient, somebody asking tips on how to do your described technique for spawn per unit, is what triggered me to search for the introduced technique.

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If we’re speaking about the identical man, he really needed the most recent particle to transcend the actor place, which is feasible with our strategies, but it surely saddens me that it now not issues now (not due to the GPU ribbon).

That is really the identical technique as Partikel’s tip proper, simply not finished in scratchpad :smiley:
and thanks for the good tip as effectively Niels!

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I’ve a query, as a result of I’m unable to learn what’s earlier than this (or extra like they’re too superior!), what does SpawnOutputInfo return? To my understanding, it appears you’re taking out the each rely of particle spawn and accumulate them to the Emitter.TotalParticlesSpawned.
It will be nice should you might clarify extra about this half, thanks.

it appears you’re taking out the each rely of particle spawn and accumulate them to the Emitter.TotalParticlesSpawned.

Yup, that’s precisely what we’re doing.

Spawn data is the construction a spawn module passes onto the engine to point that it needs to spawn new particles.
In case you open up one of many epic supplied spawn modules, you’ll discover that the final node in these modules is the one I marked in white.

So we merely copy the epic present modules and put these nodes within the image behind it to examine what number of particles this modules needs to spawn and add it to our rely.

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Howdy Niels!

I attempted your tutorial however for the second half (fixing the spawn price or spawn per unit) when compiling the module script it tells me there’s errors :

I’m undecided what to do since two of them are situated on nodes that got here from the fundamental spawn price module. The final one is the map set on the finish (the one you add) however I suppose this error is attributable to the 2 others errors.

Are you able to assist me please ?

Chances are high your module utilization flags haven’t been set solely to emitter.

I discovered this subject when spawning with the hole repair. Particles aren’t distributed evenly accross the path, I suppose it’s associated to delta time. How do you counsel to repair this?

If you’d like equal spacing, you should use a variation that snaps again the particle to it’s authentic spawn place as soon as it’s now not the final one.

Hello, sorry for my late anwser however after making an attempt to vary my module utilization I get a number of issues :Even by clearing the namespace I nonetheless get the error (screenshot present what it was earlier than):

for the second because the node was not the identical as yours I take away the half within the center however no success in clearing the error both :

For the final one the flags are good so I don’t perceive the error right here :

I copy/paste the spawn price module from epic recreation so I don’t know the place I did one thing fallacious.



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