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Whitewater flicking


Dusmus

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Hello there,

I have a FLIP from which I want to generate foam. I used the whitewater tool from shelf and i've got my foam/bubbles/spray particles. The only thing is that those particles flicks, some of them just disappear then reappears randomly.

My main FLIP sim is simulated at 150fps and is working ok.

Any ideas ?

Link to movie (10 frames only sorry) : https://vimeo.com/69166434

Many thanks.

Cheers,

Steve

(also posted on SESI forum)

Edited by Dusmus
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Yeah sorry.

Can't provide the scene as it is work related but I've reproduced a simple scene (flip colliding with a cube).

You can also find attached a better preview of the problem (foam particles in the movie)

Many thanks,

Steve

you're ignoring emit attrib and your replicate node just creates 0 particles per original (cause it's looking for emit attrib and can't find it).

Just delete "^emit" from Ignored Attributes in your whitewater_emitter node.

Edited by bloomendale
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Hmm if I delete "^emit" from ignored attributes, the emit attribute will be ignored. Tried as you said but I get the same issue.

Anyway I found a "way" by diving in the whitewatersource node (SOP), I guess the foam and bubbles aren't supposed to be separated. I mean the flicking disappear as soon as you merge the bubbles and foam together. It's doing something like each time a particle classified as foam dies, it's replaced by a bubble one.

So I'm just exporting the foam and bubbles together instead of separating them and i'll be okay. I've adusted also the min/max speed and min/max acceleration on the whitewatersource node.

Thanks for your help guys,

Cheers

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Anyway I found a "way" by diving in the whitewatersource node (SOP), I guess the foam and bubbles aren't supposed to be separated. I mean the flicking disappear as soon as you merge the bubbles and foam together. It's doing something like each time a particle classified as foam dies, it's replaced by a bubble one.

So I'm just exporting the foam and bubbles together instead of separating them and i'll be okay. I've adusted also the min/max speed and min/max acceleration on the whitewatersource node.

Sorry, just saw this. Yes, each particle can transition between different states, i.e. foam -> bubbles and back again. So if a big wave crashes down on some foam, those particles can be sent below the surface where they will become bubbles and rise to the top again, then become foam once more (within lifetime limits of course). With a thin foam layer like the default setting, the particles can transition back and forth from foam <-> bubbles quite often, causing some flickering if you try to separate them out. So it's best to render them both together if possible.

Spray is a more distinct transition that doesn't happen as often, and doing a separate spray pass can be quite effective.

Edited by johner
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