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Particle Masking/Subtraction for Fire?

I'm currently making a fire particle system, which I plan on making as stylistic as possible. I currently have an idea on what I want to happen, but I would like some help figuring out how to achieve it.

I will be using this illustrated demonstration I found to help illustrate my point.

alt text

The first stage on the left would be a standard particle system, using a set of emitters using a radial gradient material. In stage two, which I want to emulate, additional radial gradient particles would be added, with the key exception of the material subtracting the effects of specific emitters.

I would appreciate any feedback on this subject.

Product Version: UE 4.14
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asked Jan 26 '17 at 11:27 PM in Using UE4

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avatar image Luos Jan 26 '17 at 11:35 PM

we had some discussions about it on vfx facebook group/vfx forums but sadly I havent find a properly way to do it in ue4. Might be possible by combining a few flipbooks, some masking, others showing the spheres.. but.. no luck on my part.

Additional tweets showing cool tricks for it: https://twitter.com/timsoret/status/788524951959732224




additionally, i'll forward this to someone from epic. maybe he can shed some light, or well.. substract some light on this matter.

avatar image HyperThermal Jan 30 '17 at 08:43 PM

I did a little bit of looking, and I have found the SphereMask Material Expression, which can help give the desired effect. How it works is that it takes an A value (which is the position checked) and a B value (which represents where the sphere masking will be centered). This video shows the effects in better detail, and please make note of how the cube is effected by the sphere in the demonstrations in the latter half. https://www.youtube.com/watch?v=xRxkcFOhNrc

In the A value, I would be setting the position of the material and particles in world space, and the B position would ideally be the position of the particles that would have the masking effect applied to them. This is where another issue comes in: I am unsure of how to reference the position of particles from the masking emitter in the material used in the colored emitter. It seems like it would be something simple to do, but I just cannot find the right way to tackle it. Any thoughts? If I'm not clear in what I'm asking for, let me know so I can try to explain better.

avatar image Luos May 23 '17 at 06:23 PM

bump for justice :)

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