Search in
Sort by:

Question Status:

Search help

  • Simple searches use one or more words. Separate the words with spaces (cat dog) to search cat,dog or both. Separate the words with plus signs (cat +dog) to search for items that may contain cat but must contain dog.
  • You can further refine your search on the search results page, where you can search by keywords, author, topic. These can be combined with each other. Examples
    • cat dog --matches anything with cat,dog or both
    • cat +dog --searches for cat +dog where dog is a mandatory term
    • cat -dog -- searches for cat excluding any result containing dog
    • [cats] —will restrict your search to results with topic named "cats"
    • [cats] [dogs] —will restrict your search to results with both topics, "cats", and "dogs"

Office Holiday

Epic Games' offices will be on holiday from June 22nd to July 7th. During this period support will be limited. Our offices will reopen on Monday, July 8th. 

particle stepping


Currently having an issue with my particles, I'm getting some stepping in my emission I can't seem to remove. I've attached an image to illustrate it, it appears to always do chunks of particles no matter what my spawn rate is. If I up the spawn to crazy amounts it just fills those sections with more particles rather than smoother the whole thing out. The particles are GPU emitted. Any advice? Using 4.3.1

Thanks, [1]: /storage/temp/12057-particles.jpg

Product Version: Not Selected
particles.jpg (168.2 kB)
more ▼

asked Aug 06 '14 at 12:06 AM in Using UE4

avatar image

1 1 4 6

avatar image kta3d Aug 06 '14 at 01:14 AM

that usually happens when your spawn rate + particle lifetime outstrips your max-allowable particles. what is your max-count set to?

avatar image Laserman Aug 06 '14 at 01:17 AM

It's not enabled, but I raised the limit to 100,000 and made no difference on or off

avatar image Lovecraft_K ♦♦ STAFF Aug 07 '14 at 06:02 PM

Hey Laserman -

What is your Screen Alignment set to? Also could you post a screenshot of your modules in the system?

Thank You

Eric Ketchum

avatar image Laserman Aug 07 '14 at 10:36 PM

Hey Eric,

My Screen Alignment is set to PSA Square. I've attached an image of my cascade.

alt text

I've written out the important parts of the modules

Spawn : 80 Rate, 10 Rate Scale

Lifetime : 2 Min 5 Max

Initial Size : 1

Initial Color : <1,1,1,0.3>

Initial Velocity : <0,0,1200>

Const Acceleration : <0,0,-1200>

Velocity Cone : 15/20 Angle, 10/15 Velocity

Size by Life : 0 = 2, > , 1 = 10

Scale Color/Life : 0 = 1 > 1 = 0

Initial Rotation = 0/180

Initial Rotation Rate = 0/1

Size by Speed : 1/1 Speed 10/10 Max

Collision : 0.75 Res, 0.1 Res Scale, 0.05, Friction, Bounce

Thanks for any help.


capture.jpg (184.4 kB)
avatar image [Epic]homeRye STAFF Aug 07 '14 at 11:48 PM

Here are a few things you can try.

First, check the output log for this spew: Failed to allocate tiles for %s! %d new particles truncated to %d.

If you are hitting the hard GPU particle limit of 1M particles per frame you will get this error message.

Second, try "stat gpuparticles' to track the total number of particles you are using. The 1m particle limit is "per world" and Cascade has it's own "preview world" but the stats will count both.

If you are exceeding the count you can try and reduce your emission rate and increase your sprite size.

As a last effort you can try and increase the max count in the [SystemSettings] section of your engine INI file.


Add the line FX.MaxGPUParticlesSpawnedPerFrame with an amount.

1 million particles is quite a large number of particles so you may want to consider other options if you are reaching spawn limits.

avatar image Laserman Aug 08 '14 at 03:22 AM

Hey homeRye, thanks for the suggestions

I've attached an image alt text

I don't think I am reaching that many particles, but I can't tell from the stat...because when I turned them all off there were still calls going up and down for sprites spawned.

Also, I made a new tab for outputLog next to my window (in screenshot) and didn't see any error messages except for some custom json stuff. is that the log window you were talking about, or is there a different window?

thanks again for your help.

particles2.jpg (269.6 kB)
avatar image Lovecraft_K ♦♦ STAFF Aug 08 '14 at 05:29 PM

Hey Laserman -

If there was an error generated it would appear in that Output window and your usage log file located in your Saved directory in the project.


avatar image Laserman Aug 10 '14 at 11:51 PM

is it possible that my particles are too fast? 1200 initial velocity & -1200 const acceleration? does that matter?

avatar image Lovecraft_K ♦♦ STAFF Aug 11 '14 at 03:02 PM

Hey Laserman -

Are you using a vector field in your level? I am trying to reproduce your effect and I feel like I am missing something.

Eric Ketchum

avatar image Laserman Aug 11 '14 at 11:27 PM


Here is a the fountain project files, I'm not doing anything fancy. I've since changed the fountain to try and fix the problem, I've found that switching to velocity screen alignment and changing size over life to of helped, but now I don't like how the motion of the fountain goes over the top and back down down again.

It's better at the moment, but the stepping still occurs.

Thanks Eric

avatar image skyrim Jul 20 '18 at 01:59 AM

I add in project config defaultengine.ini FX.MaxGPUParticlesSpawnedPerFrame=1000000 but seem to be not work there are also lots of warming in output log

(comments are locked)
10|2000 characters needed characters left
Viewable by all users

2 answers: sort voted first

Hey Laserman -

You stepping problem is actually a texture issue and not a particle issue. The stepping you are seeing is actually your texture tiling a too regular an interval. You base water texture has two large very similar elements directly across from one another (I've circled them in the picture below.). You could paint them down a little in Photoshop and/or you could add a panning breakup texture across it. One immediate thing that I did just in Cascade was added an Initial Rotation Rate of Min -0.1 and Max 0.1 which allows the repeating pattern to slightly offset over its life which helps the later parts of the effect but the repetition can still be seen at the initial spawn.

alt text

FYI - I Temporary unplugged the Opacity to get a clean shot of the texture.

Try this solution out and let me know -

Eric Ketchum

watertexture.jpg (68.3 kB)
more ▼

answered Aug 12 '14 at 02:50 PM

avatar image

Lovecraft_K ♦♦ STAFF
36.7k 702 260 735

(comments are locked)
10|2000 characters needed characters left
Viewable by all users

I actually had another problem trying that, I couldn't find where the original game asset was to edit it in photoshop, so I just screenshot your screenshot to use it again :p anywho, yeah I tested that, and I replaced the particle with a narrow white strip, used as opacity and colour.

alt text

and set the screen alignment to velocity and then animated the asset on one axis and I'm still getting the stepping at the beginning. I'm not an fx artist, so please forgive my ignorance if I'm wrong in this field, but my thinking is that if I increase the spawn rate that stepping will get smoothed out, but I'm still getting more particles in those areas and not across the life of the particle.


sorry for dragging this out. but I am doing stuff for proposals (not games) and it needs to look right otherwise need to come up with another solution.

thanks again Eric

particles3.jpg (85.4 kB)
more ▼

answered Aug 13 '14 at 06:01 AM

avatar image

1 1 4 6

avatar image Lovecraft_K ♦♦ STAFF Aug 13 '14 at 05:56 PM

No Problem. Ok, first I did switch the new Partricle Emitter in Fountain to GPU Sprites because it was still set as CPU (Normal) Sprites and that will cause that stepping that you are experiencing. But even with that I can see the stepping you are seeing which has been caused by the Rate Scale in your spawn module. In the instance we are dealing with here you can set the rate scale to 1.0 and increase the rate itself up to 5000. This produces a smooth look without the stepping effect. With this fix and a slight change to your texture you should be good to go

Thank You

Eric Ketchum

avatar image Laserman Aug 13 '14 at 10:18 PM

ah my response is gone....tried to make this an answer and it vanished.

just said thank you for your continuing help and with more tweaks it'll be exactly how i need it, now that issue is solved.

thank you very much again Eric and everyone else that helped.

(comments are locked)
10|2000 characters needed characters left
Viewable by all users
Your answer
toggle preview:

Up to 5 attachments (including images) can be used with a maximum of 5.2 MB each and 5.2 MB total.

Follow this question

Once you sign in you will be able to subscribe for any updates here

Answers to this question