I’m coming from motion graphics and Using UE to render videos. I’m having a Niagara system and I need it to look exactly the same at the beginning and end of my video - so it’ll create a seamlessly looping video.
Is this something that’s possible with Niagara? in Houdini it can be created with Cache. I want to have the system made in Niagara without importing external data. Currently, every time I render a video the Niagara system emits slightly differently. Thanks!
Were you able to find a solution? I’m currently trying to figure it out myself. Any help is much appreciated :).
It’s technically possible, but requires a whole bunch of manual setup.
One of the ways you can do it, is by not using randomness and instead using completely predictable looping values for simulation. Setting manual seeds can be very helpful here. You can set the seed based on the id of a particle and loop the id using modulo for example.
Any thing that is manually animated using curves will also be loopable by making sure the curves align.
Lastly, the first loop might not be loopable due to not having the particle from the previous loop available. A warmup time at least equal to the loop can be helpful here.
Hope that helps.
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I recognize this is an old thread, but I figured out how to seamlessly loop Niagara systems (for the most part.) In your system, you need to go to your main Niagara Overview Node (the blue one), select it, change the Loop Duration to the length you want your loop to be (for this example, we’ll do 30-seconds), and set it to “Once” instead of infinite. Then go into each of your individual emitters’ properties panel (the orange boxes), check the “Determinism” checkbox, and change the random seed for each of them. This determinism box makes it so the particles will emit the exact same every time (for that particular seed. So if you have 2 different colored emitters, you want them to be different seeds or they’ll be perfectly on top of each other.)
Now, to get it to loop, you’ll want to save this Niagara System and have the name ending in “_Start”. Duplicate the entire Niagara System/file, change the end of the duplicate’s name to “_End”, go into this new duplicate Niagara System and all you need to do is check the box in the Niagara Overview Node (blue node) that says “Loop Delay” and set that value also to 30 seconds.
Now as the first one stops emitting at the 30-second mark and the particles die out for however long their lifecycle is, the 2nd “_End” emitter will kick in emitting the same pattern of particles (since it is an exact duplicate of the original system and has the determinism checkbox checked, just now with the loop delay.)
To render it out, create your level sequence, add your CineCameraActor and each individual Niagara System (then you have to do the plus mark, hit the “Niagara Component”, and add the “Niagara System Life Cycle” and drag it to the end of your timeline (which needs to be a minimum length of the first loop duration (30-seconds) PLUS the maximum life of the particle (so if it’s 13-seconds, you need to render a bare minimum of 43 seconds, though you’ll want to add an extra 5 seconds for the reason below.)
Here’s the catch: UE5 Niagara for some reason does not loop 100% perfectly. You’ll notice your particles from the beginning of your scene match near perfectly at the 30-second mark when you export it, however, if you have Curl Noise on, the curl noise won’t loop which is annoying. And also, for some reason there are additional new birthing particles that come into scene at the 30-second mark that aren’t there at the beginning. So to make this look like a seamless loop since it’s SO close but not perfect, drag your export into a 30-second Premiere or After Effects comp, drag the footage back so the end of the 30-second comp is also the end of the footage. Now cut the tail of the footage at the front end (0-second mark), duplicate it, and drag that whole duplicate to the end of the timeline (so that frame that’s at the beginning of the comp on your first footage is now all the way at the end of the timeline on your duplicate footage.) Now on the duplicate one, add a 4-second buffer on the footage and animate the opacity from 0 to 100%. This way, when your comp hits 26-seconds, a duplicate of the footage it’s about to roll back to will fade in over 4-seconds, and by the time it’s at 100% opacity, that final frame at the 30-second mark is the exact same as the frame at the beginning of the comp. If you do this to a non-looping Niagara system, it will loop to the beginning, but it’ll be super noticeable. However, with the loop set up the way I talked about, the difference will be incredibly negligible, because it’s really only minor positioning differences due to the Curl Noise and extra particles that fade in for some reason.
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Thanks for the detailed answer! It sound super-close to perfect, I’ll give it a go on the next Niagara project. Thank you.