Hello guys.

i´m doing some ocean splash tests, but i can´t find a proper info (updated one to H13, or h12.5 at least) or tutorial for pass creation for flips.
What i wish is to do some advanced composition on fluids like i see on demos of vimeo showing ocean passes with vorticity etc…
my questions are:

1. How can i create a fluid vorticity pass, and fluid velocity pass to help in composition?
2. How to set to use directly (vel and vorticity) in shader, with some “fade effect” too?
3. Where i create vorticity in first place? i cant find anywhere…

if all this come from cached sim, what the correct approach? How to save vorticity on cache?

can anyone help with a simple scene showing the workflow?

thanks in advance!

Malcolm.

I have a file which might help a bit:

http://fx-td.com/?p=329 [fx-td.com]

Vorticity can actually be computed quite easily post-sim with a few vdb nodes to measure curl from the vel field and then length of curl, which is vorticity. You can put that back onto the particles using an attrib from volume and use those attributes to drive the shader and/or color (I have a vop setup for that in my file)

I have a different setup in my file for doing vorticity, where it does it in the flip sim. It tracks with the particles and fades out over time, so if an area gets foamy, the particles will stay foamy for a bit before going back to normal. Either way is fine, I prefer having it follow along with the particles a bit, as opposed to being just a snapshot of current vorticity, but in a lot of cases, vorticity post-sim (like mentioned above) is more than enough and is a lot faster than doing it in the sim like my file. Nonetheless there should be some helpful stuff in that file for you.