Please see this video here: https://www.dropbox.com/scl/fi/1a2tvj68n5qkuclfy24oe/Foam\_flicker\_and\_disappear.mp4?rlkey=ef3t93wp3m0y3bmo460otnv9h&st=1ua6objz&dl=0
Better download the video from the link, as the online player is downgrading the quality a lot, and the issue is not as noticeable.
It’s a simple scene with just the ocean and a ship. The lighting is made by an HDR dome. Only the foam is rendered in the video. I’ve hidden the splashes and mist to see the issue better. There are actually 2 issues. The foam is flickering in terms of brightness, and then the particles are randomly disappearing and appearing in the form of long stripes. All of that is happening outside of the liquid simulator. Inside it’s all good.
Here’s a screengrab of my foam shader:
I was able to solve the brightness flickering by increasing the vertical offset by 0.1m, but the particles still keep on randomly disappearing and appearing. Like this: https://www.dropbox.com/scl/fi/15fw1sio7o3onltempnvp/Foam\_disappear\_verticalOffset-0.1m.mp4?rlkey=aojgpqnk6zl9mwq8uef6132t1&st=sydc8am0&dl=0
By the way, for the vertical offset, I used the wonderful hidden switch “vertoffscond”, created by Svetlin Nikolov, to offset only the particles outside the simulator. You should definitely make it exposed in the UI in some next version.
Other than that, I tried some other settings of the foam shader, but nothing really seemed to help. I even tried rendering the ocean in a Cap Mesh mode, just to see if the water isn’t somehow killing the particles, but the same thing happens: https://www.dropbox.com/scl/fi/852z2tmfxc51u7uqqtgw4/Foam\_disappear\_CapMesh.mp4?rlkey=xwymek0gr1d0i8itdwq1pt9i2&st=8jqynue4&dl=0
The particle simulation itself should be fine because in the viewport it looks good: https://www.dropbox.com/scl/fi/wajq5lwmpjtjg8lzk0mdq/Foam\_viewport.mp4?rlkey=cb0uxfy5jxxihczcdekkx9gee&st=bkwsu6tl&dl=0
Also, if I change the foam shader to render as points, then it doesn’t flicker or disappear anymore. This is what it looks like: https://www.dropbox.com/scl/fi/u8qtafezzxkmedbp2h596/Foam\_points.mp4?rlkey=pesxra6iha67t62ov17j3c5uo&st=ky2a3lla&dl=0
However, I’d like to avoid using points because, as you can see in the video, the render quality is not as good as with the bubbles. Also, in my shot, the camera is moving from an overhead view smoothly to a close-up, and there the points wouldn’t really work.
Is there anything else that I can try to solve the disappearance of particles?
Oh by the way, I did all the rendering with the latest stable v5.23.00. I tried to render with the latest nightly build 33084, but 3dsmax would crash to desktop as soon as I hit the render button.