Houdini Ocean Toolkit for 3DS Max- Foam Tips.

I've made a blog note mostly just to remind myself, but also because I had to do so much expermentation to find this out- hopefully it will help someone else. Tantalised by the little Foam checkbox at the bottom of the HOT rollout, but frustrated that there is absolutely no documentation on how it works...? Here you go.

I'm going to assume that you're already familiar with HOT and have your ocean plane set up and animating how you like it, and that you have the Foam box ticked 'on'. From there it's actually surprisingly simple, though it took a lot of poking around for me to figure it out (why there couldn't just be a document explaining it I don't know). Firstly, you can immediately see how the foam shows up if you go to the object properties of your ocean plane and set it to vertex channel display. Now you should see a black and white surface in the viewport, where white is the foam. The more polys you have in your mesh, the better the detail in the map.

There's a couple of things you can do with this. First, you can assign a material to the plane and then set the diffuse as a vertex color map. It will only show up in the material editor as the standard kinda rainbow sphere, but if you render you'll see the same black and white procedural map that you get in the viewport. You can then plug this into a blend material if you want to generate it all procedurally. Or, you can turn your render settings to 'active time segment' and then use 'render to texture' to bake out the black and white map as frames. From there you can use it as a displacement or bump map, a blend mask, or to drive particle emissions and of course you can re-use it. It also might be more render-friendly to use maps if you're network rendering and not all machines have the HOT plugin, or just to keep the poly count down.