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Spawn particles based on texture

This might be a bit of a stretch, I googled with no avail. I figured it won't hurt asking.

Is there a way to drive the spawning of particles based on a texture or a material?

I'm trying to spawn particles based on an animated texture. The answer seems to be no and I can't find real alternatives to this.

Product Version: UE 4.12
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asked Jul 27 '16 at 02:53 PM in Using UE4

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vernocchi
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avatar image Luos Jul 27 '16 at 02:56 PM

hello Vernocchi, can you perhaps tell me in more detail what you want to achieve? Perhaps I can help you, or know someone who can.

cheers!

avatar image vernocchi Jul 27 '16 at 03:10 PM

Essentially I'm doing a pretty straightforward effect of having an object appear by animating an opacity mask (something similar to this: https://www.youtube.com/watch?v=6aflOXRrGTI). What I'd like to do is spawn smoke particles where the transition happens. There seems to be no way to do this other than perhaps using a moving invisible mesh to do it but it would not work with complex meshes.

Any ideas?

avatar image DamirH Jul 27 '16 at 04:06 PM

I am assuming your effect is similar to the one in the video, i.e. the transition goes in one direction. Well you most likely have a timeline or such to drive the current percentage of the transition (assuming it moves, i.e. the object burns away into nothingess). What you could do is use that timeline or whatever you have to drive a proxy collision box that roughly covers the transition area. It won't be pixel perfect but for purely cosmetic effects such an approximation is usually good enough.

avatar image vernocchi Jul 27 '16 at 04:42 PM

Ah, yeah that would be feasible but this would require a fairly complex collider on the mesh, right? Since I essentially need the outline of the sliced mesh. Thanks though, this points me in a good direction!

avatar image DamirH Jul 27 '16 at 09:01 PM

This really depends on how precise you need it to be. If you REALLY need a pixel perfect collision with the outline then this won't work for you. If you just want to fire off a smoke particle when the player "shoots at the transition" then this is bound to be good enough.

avatar image gldsgns Apr 11 '18 at 01:46 AM

I'd really like to know if there is a great answer for this. Emitting particles with a grayscale map or even procedural noise seems a powerful way to approach a variety of effects. Is there not a simple way to trigger emission based on image's RGB data and map particle spawn location via mesh UV coordinates?

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