Two thirds of ink simulations are black.

[LudvikKoutny]

Hi,

first of of, I would like to thank you a LOT for all the various presets in PhoenixFD 3.0. I almost never used presets in any software, as they were often either too simple and basic looking, or rubbish in general, but presets in Phoenix 3 are immensely useful. I just spent this entire day playing with them instead of doing the work I am supposed to. They are just so good, high end looking yet so quick to simulate. It's a great confidence booster in what Phoenix 3 can achieve and how fast it can simulate.

Anyway, I got a little bit stuck with Ink preset. For some reason, two thirds of the simulation are always black, regardless of scene lighting or color setup in foam helper. This is how it looks:


I am curious what did I miss here.

Thanks in advance

[LudvikKoutny]

No one?

This is a bit urgent as I would like to do some ink effect for my current job. It seems that the color of the ink is somehow limited to the area surrounding the emitter, but I wen't over most of the settings that could affect the look, but nothing I changed did seem to have any effect :/

[georgi.zhekov]

Hello,

Can you send us the scene so we can check it out?

[LudvikKoutny]

Hello,
Can you send us the scene so we can check it out?

Yep, sure, here it is:
Ink.zip
But it's just completely empty new scene with sphere created in middle, and then just ink preset from Phoenix toolbar applied on it.

Using PhoenixFD 3.00.01

[georgi.zhekov]

Are you using V-Ray 3.5 Beta builds? There seems to be an issue with Adaptive lights. If you turn those off it should be working.

[LudvikKoutny]

Are you using V-Ray 3.5 Beta builds? There seems to be an issue with Adaptive lights. If you turn those off it should be working.

Ohhh... Yes! Using 3.5 beta. Forgot to mention that. It did not occur to me at all it could have an effect on point shading... Thank you very much!

[LudvikKoutny]

Hi,

I have one last question. It seems that the Ink preset is set up by default also with some temperature. PHXSource has animated temperature output, and if I select temperature channel in simulation output, I can actually see it simulated along with particles:


I, however, can not figure out how to go about making this temperature output to render. I tried various things in render options window, such as playing with smoke opacity setting, trying fire with source set to temperature, trying smoke with source set to temperature, etc..., but nothing worked. I would be very thankful for a quick hint on how to make temperature channel render as smoke. I would like to use it as sort of foggy background to the Ink points, to make them blend together little bit better.

Thank you again.

[georgi.zhekov]

This one is a bit tricky to figure it out on your own - we have disabled the Rendering of the Simulator from the Object Properties for the Ink preset. Turn that on, set the smoke opacity to be based on Temperature



And it should work. Make sure you have temperature enabled in your output settings

[LudvikKoutny]

Yep, I would probably never figure this on my own... Thank you very much!

[Svetlin.Nikolov]

Just dropping it with some additional info in case it would be useful - the temperature is needed in order to force the particles to descend or ascend when the gravity is enabled - temperature above 300 (room temperature in Kelvins) would make the fluid rise, while temperature below 300 will make it fall down. If you create several emitters and apply the Ink Quick Setup simultaneously over them, they will not only have different colors, but different temperatures as well.

[LudvikKoutny]

Thanks, that's very useful. I was figuring out how to vertically direct the ink, and originally assumed I would use gravity, but temperature makes more sense.

I got one more question though. There are two hidden objects in the scene: PHXParamMod001 and PG [Particles of Cylinder001].

I am curious, what are these for? Especially the PHXParamMod001. Does it do something important that the ink would not work without?

[Svetlin.Nikolov]

The first one is a discharge modifier - those are new to 3ds Max, though they've been in Phoenix for Maya for some time now - https://docs.chaosgroup.com/display/...arge+Modifiers We should do a tutorial about them soon, as they are an interesting addition and allow you to create some more customizable setups.

The second one is an object that represents the particle systems of the simulation, so that the single simulator can provide several particle systems to the particle shaders or other plugins simultaneously and you'd be able to choose which system you want - foam, splash, liquid, etc

[LudvikKoutny]

Yep, thanks. Just took a look at it, and in this case, it's used to force particle emission only on the bottom of the emitter geometry in Z axis.

I have yet one more question.

I am emitting particles from moving mesh, and it seems that particles do not spawn on top of the mesh but inside of grid cells that are intersected by emitter geometry. This results in very distinct and obvious popping of the new particle clusters during simulation, even when having very fine grid (and therefore very long sim times).

Is there any way to work around it/ reduce it?

Thanks

[Svetlin.Nikolov]

If you already use Surface Force in the source, then the problem you have is that if you spawn drag particles by the source in a fire/smoke sim, they indeed do not follow the surface precisely but are instead born into the entire voxel volume.

Alternatively, you could use a liquid simulator and spawn foam or splash particles by the same source, but they will not behave the same way and there are still not drag particles in the liquid solver.

I hope soon we'll be able to port the voxelization from the liquid sim to the fire/smoke one and the drag particle birth would precisely follow the geometry, but for now it's just increasing the resolution that I can think of as well..

[LudvikKoutny]

If you already use Surface Force in the source, then the problem you have is that if you spawn drag particles by the source in a fire/smoke sim, they indeed do not follow the surface precisely but are instead born into the entire voxel volume.

Alternatively, you could use a liquid simulator and spawn foam or splash particles by the same source, but they will not behave the same way and there are still not drag particles in the liquid solver.

I hope soon we'll be able to port the voxelization from the liquid sim to the fire/smoke one and the drag particle birth would precisely follow the geometry, but for now it's just increasing the resolution that I can think of as well..

That's fair enough... I was just wondering if I am not missing something. Thanks anyway