Foam much slower to render in PhFD 3.12 than in PhoenixFD 3.0

[Zakkorn]

Indeed, I hope that using the same scene as you will help find the answer.

You will find it as you always do.

I want to explain the rendering slowdown a little more, so you will have a better understanding.

Lets say i want to render for the first time (after I load the scene) a frame with 200.000 foam particles.
After I hit render, it would take about a sec to begin rendering (begin rendering = we see the render buckets forming on the image).
Lets say after that I want to render again the same frame.
It would take about 20 secs till we see the render buckets appear. And the more the foam particles the more the time we wait for the render buckets (1million+ foam would make this time period about 1 min)
Now lets say I want to render an animation, after the first time render (the time we first render the frame without this "delay")
It would again take some secs on the first frame but only on the first. The rest of the frames that contain foam will render without delays.
Thats the strange thing.

Regards,
Zach

PS. Do you have a discord channel? Because will be easier for me to explain the issues by voice.

[Svetlin.Nikolov]

Indeed, I am doing the same thing, but it starts quickly every time. Can you tell me the exact version of Max 2017 you are using, so I can get as close as possible to your setup using the beer scene here?

[Zakkorn]

I am using Max 2017 with SP 3

[Svetlin.Nikolov]

Hey, thanks to the scene you sent, the issue is finally reproduced! Will ping you when the fix is in the nightlies!

Cheers!

[Zakkorn]

Hey, thanks to the scene you sent, the issue is finally reproduced! Will ping you when the fix is in the nightlies!

Cheers!

Oh thats great!
Good Job again.

Regards,
Zach

PS. Does the fix include the solution as to why my foam is not getting any speed boost after the latest nightly?

[Svetlin.Nikolov]

Hey, the fix for the slow second render is in the nightlies now. However, the speed difference is there on our machines - and there is a specific thing about it - you will get a higher speed up the more bubbles you have intersecting the liquid surface. If many bubbles are above or below the surface, there won't be that much of a speedup.

Cheers!

[Zakkorn]

Hey, the fix for the slow second render is in the nightlies now. However, the speed difference is there on our machines - and there is a specific thing about it - you will get a higher speed up the more bubbles you have intersecting the liquid surface. If many bubbles are above or below the surface, there won't be that much of a speedup.

Cheers!

Oh great, thanks
What do you mean by the "more bubbles intersecting the liquid surface"?
You mean the situation when the bubble goes from inside the liquid -> above the liquid?

Regards,
Zach

[Svetlin.Nikolov]

Yup, the bubbles are spheres, and the problem was when they were half-submerged in the liquid

[Zakkorn]

Ok thanks for the answer. I didnt think something like that will cause so much slowdown

Regards,
Zach

[Svetlin.Nikolov]

Oh, the reason is much more in depth, but this is the way for you to measure it intuitively without having the burden of technical details - the change affects particles floating exactly on the liquid surface, so the most of these you have, the quicker it will render now.

Cheers!

[Zakkorn]

Thats why someone could see speed difference on the Beer project for example.
Because on my project that I work right now (by the way I will open a new thread as I have a new issue, ...I always cause you trouble ) I render the bubbles only under the surface, that why I ddin't see any difference.

Regards,
Zach