Particle System FadeIn/FadeOut?

Gazu · Jul 2015

Hi Guys!

I need a FadeIn and FadeOut for my Particle System I´m working on.
But i stuck at that.

I dont know how to make a smooth Fade In and Fade Out.

I created this Thread in the UnrealEngine Forum:
https://forums.unrealengine.com/showthread.php?76410-Particles-gt-Fade-IN-OUT-Not-facing-Camera

I tought maybe about a Color Over Life with 3 Elements.
Black , My Color and Again Black. But that doesnt work, i dont know why.

So can somebody help here?

Gazu

Obscura · Jul 2015

How your material set up? You need to multiply a vertex color alpha to get the alpha channel working(opacity slot). Also, you need AlphaColorOverLife. Maybe its just the ScaleColorOverLife now, I don't know, I haven't tried particles in UE4, but it was like how i described, in UDK. It should be the same or almost the same with 4 too.

Gazu · Jul 2015

Here it is.

Obscura · Jul 2015

multiply the texture(that goes into the opacity) with the particle color's alpha. Also, I think you must need that scale color(or alpha color, sorry I don't exactly remember how its called) thing in the particle

Gazu · Jul 2015

The Material is Transparent, but i cant fade it

I would like that this is some Kind of Light which fades In or ON and then it fades out or off.
And this all maybe in 1 sec.

Vailias · Jul 2015

For the material, make sure you're multiplying the particle color's alpha with the texture's alpha, then plugging that into opacity.

Then just use a color over time, or color over life block (whichever is more appropriate) in the particle system and animate the alpha curve from zero to 1 and back in whatever timing and smoothness you need.

that will fade your particles in and out.

Gazu · Jul 2015

The Fade is totaly bad

Also the Curve is fine, isn´t it?
He fades, but not total dark and that i dont understand,because i give him 0.5 sec to be totaly dark. Now its more like Blue Police Light.

Gazu · Jul 2015

Ok i got it...
The Numbers in the Curve Editor for example : 0.10 means 1 sec.
I tought it is 1/10 of a sec....

Thanks guys..

Gazu · Jul 2015

Or am i wrong?

Can someone explain the Timeline?
Does 0.10 means 1 sec?

Because when i set the Lifetime Min/Max to 4 seconds, and fadeout @ 0.40 i doesn´t work well.

Vailias · Jul 2015

That timeline is in percentage of lifetime.
So the precise time it fades in at is 0.1 * lifetime. So particles with a short lifetime will fade in and out faster, and particles with a longer life will fade in more slowly.

Gazu · Jul 2015

Vailias, thank you!

I will try to get it with a Lifetime of 4/4
Because now it looks a bit gradually

So is 0.4 the right Value for a Fade IN when the Lifetime is 4 min and max?
And to be clear : 0.4 not 0.40 ?

Vailias · Jul 2015

The *right* value will be what you want it to look like.

If you have a constant particle lifetime of 4 seconds, and the fade in peaks at 0.4 then it will take 1.6 seconds to fade in. (4.0 seconds time 0.4 = 1.6 seconds)
Also, 0.4 and 0.40 are the same value.

you may want to look over the documentation for Cascasde.

Also, there's a tutorial series here that may be of use to you.

Particle System FadeIn/FadeOut?

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