Twister test (very low poly)

[Dune]

Trying to get a twister to work. I still have to find a way to rotate the upper layer, but only near the center. Outside needs to stay put, kind of, or at least turn less.

[Hannes]

Cool!! You may need to copy and paste the upper portion cloud layer(s) and mask out (simple shape shaders?) the lateral area and reduce the speed of the rotation on those.

[Matt]

The Vortex Warp Shader gives you this radius-dependent rotation for free. You probably don't need to do any rotation at all, just animate the vorticity parameter.

https://planetside.co.uk/forums/index.php?msg=204433

[Dune]

You may need to copy and paste the upper portion cloud layer(s) and mask out (simple shape shaders?) the lateral area and reduce the speed of the rotation on those.

That's exactly what I did after posting, but Matt's solution is something I thought about too... even added a vortex shader, but never hooked it on or thought about what to animate.

Thanks guys! I'll experiment on. Interesting link, by the way. Totally forgot I've been in this situation before. Must be getting old

[Dune]

Disabled the transform shaders and just put the vortex in. Animated vorticity from 0-1 in 200 frames, and added an additional animated mask to lower the funnel from frame 1-100. Works quite nicely 
I don't know what would happen or what needs to be done to keep this vortex running in maybe another 400 frames though, animate to vorticity=3? I guess so.

[DocCharly65]

Oh wow! Big things happened here since I started my technical and social media break some weeks ago... 
Great Ulco!