What Defines Above Water or Under Water for Particle Shader?

[Joelaff]

How does the Particle Shader determine that bubbles are above or under water?

I am seeing a ton of underwater foam rendering when I have it set to only Above Water. (I have a carbonated beverage in a glass.) When I set it to only Under Water then it works correctly.

Is this a bug, or something on my end?

Also, Cutter Geometry in the Particle Shader seems to NOT work to remove the Under Water particles when I have the Particle Shader set to Above Water. So there seems to be no workaround short of using something like Magma Modifier to delete the particles, or volume select perhaps.

Max 2021.1 and Nighlty build 2021012030547

Maybe I should try a new nightly, but that is pretty recent.

[Joelaff]

It is possible that the reason I was experiencing this was that it was the particles that got trapped in the other goemetry from the B2B interaction that were being treated as Above Water because they are indeed outside the liquid. I got that B2B thing sorted and will have to see how that affects things when the sim is done. I didn't try rendering yet after figuring that out.

[Svetlin.Nikolov]

Ah, was it B2B at fault in the other thread?

The connected Liquid Simulator is the surface that gets tested in order to determine if a particle is above or below (inside or outside) the liquid.

Will try a simple setup now with Above Water and a Cutter...

[Joelaff]

Ah, was it B2B at fault in the other thread?

The connected Liquid Simulator is the surface that gets tested in order to determine if a particle is above or below (inside or outside) the liquid.

Will try a simple setup now with Above Water and a Cutter...

Yes, I put that in an edit and I think you didn't see that. I just re-posted about it.

So those particles were stuck in the glass and ice cubes. Thus they were NOT within the liquid. So thus they were NOT above the water.

I can't guarantee that the cutter issue was not operator error regarding these particles that I thought were under water, that weren't because they were stuck in the objects.

[Svetlin.Nikolov]

Ahhh, I just put my larger glasses on and re-read what you wrote. Indeed if they were inside the geometry, they would be outside the liquid. BUT, particles in Phoenix should die if they get inside Solid geometry, so this is still suspicious and sounds like either an issue, or more factors are at play...

[Joelaff]

Ahhh, I just put my larger glasses on and re-read what you wrote. Indeed if they were inside the geometry, they would be outside the liquid. BUT, particles in Phoenix should die if they get inside Solid geometry, so this is still suspicious and sounds like either an issue, or more factors are at play...

Interesting. Well, I may be able to send a scene if nothing starts to jump out at you.

I had sticky off, patterns off, wetting off, etc. I mean everything was off... Splashes were off too. I was still getting the issue. The only thing that got rid of it was the Tuner to delete the particles that were close to the geometry (as mentioned in the other thread).

[Svetlin.Nikolov]

Yes, if possible, please send it over

[Joelaff]

Yes, if possible, please send it over

I just sent it to Support - Subject: PHX: Particles Pushed into Geometry Possibly by B2B

I will update this tomorrow after I get the ticket number.

Thanks for looking into this.

[Svetlin.Nikolov]

Awesome, thank you! Will ping you we know more...

[Joelaff]

Cool. That scene is a WIP of course. I realize that I need to remove Liquid from the Particle Tuner that deletes the particles because right now it makes the liquid slowly disappear! LOL.

[Joelaff]

Actually, even with the particle tuner deleting the particles in the glass geometry I am still having trouble getting the Particle Shader Above Water mode to work right. It is rendering all the particles in Above Water mode. If in the scene I sent you render only PhoenixFDLiquid001_FoamShader001 you still get the foam below the water when you should not.

[Joelaff]

Honestly, I am not sure what it is rendering. It's not rendering all the bubble below the water, but it looks like some. Maybe they are still in the glass geometry. Ugh! This one is going to make things difficult.

[Joelaff]

I wonder if I could duplicate the Liquid and adjust the Iso level on the duplicate to control where the cutoff for above/below water is (but render the original liquid).

Or I may try with my Particle Tuner to NOT check velocity, which I think is likely the issue. Of course the real issue is that those particle shouldn't be getting in there anyway.

[Svetlin.Nikolov]

Hey, sorry, still waiting for the scene to reach me...

[Joelaff]

Hey, sorry, still waiting for the scene to reach me...

Is there a direct address that is better? Private messages to you on the forum are disabled.