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Size Over Life - Particle Issues

Hey all,

I'm working on a reasonably layered particle emitter and I'm hitting a wall.

I want the particles to scale up into existence and then scale down on the way out. Some of the particles do this perfectly and some flash on and then flash off. I'm stumped.

Product Version: UE 4.14
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asked Apr 28 '17 at 04:46 AM in Using UE4

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4 answers: sort voted first

Thanks so much again for your help IGorilla, I think it was the PSA Velocity, it's now aligned to the camera I'm using and it seems to be behaving far better.

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answered Sep 03 '17 at 01:29 AM

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This all looks fine as far as I can tell. Perhaps there is something in the material's opacity control, or something else inside cascade messing with the alpha/opacity of the materials.

additionally, just a small tip: if you want them to ease in/out a bit better set the interp mode to auto or auto clamped.

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answered Apr 28 '17 at 10:19 AM

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avatar image makkuro_ Apr 28 '17 at 07:44 PM

Hey Luos, thanks for the reply. I had a Color Over Life module that I thought might be doing exactly what you said, but even once I got rid of it, still the flicking on and off of some particles, so odd! That's the only thing I can imagine is controlling alpha or opacity on it.

And thank you for the note about interp modes. I couldn't see a difference in my case between the auto or auto clamped, but both look better than the linear.

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Hey all, I'm still struggling with this, anyone have any ideas? I'm not really able to progress with my project until I can solve this silly little problem!

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answered Jun 21 '17 at 06:44 PM

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Can you show the material that you are using and a screenshot of all the modules you are using to see if some might conflict? <3

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answered Jun 21 '17 at 06:49 PM

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avatar image makkuro_ Jun 21 '17 at 07:40 PM

I'm terrified that it's something basic and stupid and I just can't see it. Thanks so much!

avatar image Ninjin Jun 21 '17 at 08:12 PM

I just tested SubUVs on my particle system, it should just work with the Size By Life module. You might want to add the screenshot with your modules <3

avatar image makkuro_ Jun 21 '17 at 08:21 PM

Sorry, I can't seem to find my Modules, I'm happy to upload them once I find them though!

avatar image Ninjin Jun 21 '17 at 08:39 PM

You are writing they flash on and off. It's not something as simple as increasing the min lifetime by any chance? <3

avatar image makkuro_ Jun 21 '17 at 08:47 PM

I just to check, bumped the lifetime to 5 instead, still ones disappearing and reappearing randomly amid the smooth growing and shrinking ones. It's so weird.

avatar image Ninjin Jun 21 '17 at 08:58 PM

My next wild guess is wrong numbers for the SubUVs.

avatar image makkuro_ Jun 21 '17 at 09:02 PM

Like in the distribution Min/Max?

avatar image makkuro_ Aug 22 '17 at 05:34 AM

If you have time I'd really appreciate working through this before I give up, hehe.

avatar image Ninjin Aug 22 '17 at 07:26 PM

Somehow lost this answer, so sry I guess <3. When you click on the Particle Module "Required", go to SubUV and set the SubImages Horizontal/ Vertical and set the Interpolation Method to Linear. Also might want to check "ScaleUV".

avatar image makkuro_ Aug 22 '17 at 08:21 PM

Don't be sorry at all! Everyone here has been so patient with me, I'm very grateful.

No luck with the SubImages setting, it was already on Linear. Checked the ScaleUV but didn't notice any huge difference?

avatar image Ninjin Aug 22 '17 at 08:57 PM

I would set your last point in the SizeByLife module to In Val: 1 and every Out Val: 0_0_0

Also, I just followed this tutorial and everything seems to work. tldr; Add another Particle Module called "SubImage Index" and in the module, set the 2nd Point to 64 if my eyes are not lying to me.

avatar image Ninjin Sep 03 '17 at 12:58 AM

Is my last solution not working for you? Would be great to hear if it worked or not.

avatar image makkuro_ Sep 03 '17 at 01:28 AM

Hey Ninjin, sorry for the radio silence, had to get on with other projects. But thanks to you and IGorilla I found what I think the culprit was, which was the PSA Velocity, which is now attached to the camera I'm using. Thank you both for your help.

avatar image IGorilla Aug 22 '17 at 07:51 AM

My guesses:

  • Due to different lifetimes it might seem some are flashing

  • your particles are rotating making it seem they flash on and off

  • something with your subuvs

If you dont do the size over life, the particles work fine?

avatar image makkuro_ Aug 22 '17 at 08:25 PM

Hey IGorilla, thanks for your response. In regards to your thoughts:

  • The "cut off" that's happening seems to be either at the start or end of the particle life, so it'll "blink" on, move around growing, and then "blink off" rather than growing and shrinking out in and out of existence, while others do exactly what I want.

  • Don't have any rotation set, so I don't think that's it.

  • Could be something to do with my SubUVs, but wouldn't that effect all of them?

Without Size Over Life, the particles all blink on and off, so hard to tell if whatever is causing the problem is still there.

Thanks again!

avatar image makkuro_ Aug 22 '17 at 08:35 PM

Ah! Possible mini-breakthrough brought on by your rotation question IGorilla. Switched off Orbit and I think it stopped happening (even though I lose my beautiful particle movement)! What is going on in that module?

avatar image IGorilla Aug 22 '17 at 09:51 PM

does your particle maybe adjust its rotation to the particles velocity? think its called PSA Velocity or something, not sure... maybe try some settings here

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