Making a Donut-Shaped Cloud

ares2101 · January 23, 2013, 02:11:22 PM

I've looked around and I see this have been addressed before, but I'm not understanding it. What is the simplest way to create a donut-shaped cloud? I've got a dense localised cloud forming a disk and I can't seem to get a hole to form in its center. I've tried putting a camera inside it and using a distance shader, but to no avail.

Zairyn Arsyn · January 23, 2013, 02:18:52 PM

maybe try using the painted shader?
as a blending shader, hmmm...

mhaze · January 23, 2013, 02:26:38 PM

Image shader! blurred white torus on a black background used as a mask for the cloud density shader.

Zairyn Arsyn · January 23, 2013, 02:36:53 PM

now your on your way,

i'm sure it would also be possible to do this with blue nodes...
but i'm not going to go there...

cyphyr · January 23, 2013, 02:51:52 PM

Two distance shaders merged on top of each other should do it.
Plenty of other ways.

mhaze · January 23, 2013, 03:05:59 PM

Nice one, never seen that before let alone thought about it

mhaze · January 23, 2013, 03:06:59 PM

You colud do the same thing with 2 SSS subtracted from one another

cyphyr · January 23, 2013, 03:23:55 PM

I think mhaze's version is probably better

ares2101 · January 23, 2013, 05:03:47 PM

Quote from: mhaze on January 23, 2013, 03:06:59 PM
You colud do the same thing with 2 SSS subtracted from one another

How exactly do I do that? I'm having no luck with other methods.

Dune · January 24, 2013, 01:32:36 AM

Like this, but then attached as blender to your cloud fractal.

ares2101 · January 24, 2013, 10:11:59 AM

Quote from: Dune on January 24, 2013, 01:32:36 AM
Like this, but then attached as blender to your cloud fractal.

OK, I did all that and while I see some progress, it's not working perfectly. You can see a change in the cloud's appearance in the middle, but I can't seem to make that an actual hole. I tried tweaking the depth of the cloud, but that didn't do much. As a test, I attached the two SSS and merge shader to a displacement shader on the ground and got a donut shape, so I know they work.

If it helps to figure it out, if I turn off Localise on the cloud, it becomes a total overcast, so the cloud appears to not be constrained by the two SSS.

Dune · January 25, 2013, 04:10:20 AM

If your cloud fractal is blended by something (anything), the cloud coverage messes up things. So turn that to zero again and try to increase/decrease cloud coverage inside the fractal. I think that's the culprit.

ares2101 · January 25, 2013, 12:10:13 PM

Quote from: Dune on January 25, 2013, 04:10:20 AM
If your cloud fractal is blended by something (anything), the cloud coverage messes up things. So turn that to zero again and try to increase/decrease cloud coverage inside the fractal. I think that's the culprit.

OK, I'm seeing some improvement, I no longer need Localise on for it to be contained around the mountain. However, I still can't get the hole, even after trying to tweak other stuff as well. I'm attaching the relevant nodes, maybe that will help things.

Dune · January 25, 2013, 12:16:13 PM

You have to subtract one from the other 100%. The merge shader still was at 0.5.

ares2101 · January 25, 2013, 12:20:28 PM

Quote from: Dune on January 25, 2013, 12:16:13 PM
You have to subtract one from the other 100%. The merge shader still was at 0.5.

Oh, so that's what that value is. Never really used merge shaders. This is the second time today such a small thing has vexed me in a project. Thanks Dune.