Would like to get a deep fluids setup like in the picture below:
http://hectorsalva.com/wp-content/uploads/2012/08/in-our-dreams-dreams-1600x1200.jpg
We would like the cloud like formation to be revolving. We are new to fluids having done fire mainly and are not sure how to proceed for such large scale effect.
Any help is deeply appreciated.
Best Regards
-tejvirs1
I’ve attached a simple textural fluid( no grids) that roughly mimics your reference image.
I made it hollow on the inside by making the opacityInput “center gradient” then reversing the opacity graph. I then textured opacity to create the clouds and made the fluid Z Size large so it was more of a long elipsoid or cylinder than a spherical shell.
You could animate with simple rotation of the fluid( or animating the rotateZ attribute ), perhaps combining with animation of the texture time. If you needed to sculpt more clouds you could enable the density grid and set opacity input to density then paint the density values. You could start with density values that match the values of the center gradient. Note that with the opacity graph setting on this fluid you would get clouds where density is low and open spaces where density was high.( easy to reverse ). With a density and possibility velocity grid you could also do a dynamic simulation, but you might also want set the coordinate method to grid so that the texture moves as well. However the texture will get streaked over time, so it would only work for a short or very slow animation.
I have no words for this awesomeness, Thank you very much Duncan !
we are so fortunate to have you around 
Hi Duncan, Many thanks for this huge favour.
Is it possible somehow to initialize a dynamic grid attribute like Density from a texture provided value. Will it require some deep scripting.
We would like to make the density, velocity grids dynamic and here filling the density values manually does not seem easy. We would also be setting texture coordinate method to grid.
Best Regards
-tejvirs
You could run the command “bakeFluidShading 1.0” with your fluid selected. Note that this might take a while to run for a high res fluid. It will create a new fluid that is non-illuminated and non textured, but has a color and a density grid baked to the values of the original fluid. The original fluid is hidden after the operation. One could create an initial state cache for the density grid of the fluid then unhide your original fluid and use that same cache to initialize its density. If you didn’t want the effect of the texture(only the center gradient) on on the density you could temporarily disable it when doing he bakeFluidShading. Also you might need to do things like temporarily set the opacity gradient and transparency to the default values.
You could look at bakeFluidShading.mel in your scripts area( it is a mel procedure ). It could modified to just bake out density gradients and such. Note that the argument to bakeFluidShading needs to be 1.0, so the resolution between the original and baked fluid match and one can thus transfer initial state caches.
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