[Sidefx-houdini-list] Ocean surface with flip sim

Miles Green miles.green at al.com.au
Mon Jun 2 21:22:58 EDT 2014

Hi François,
  I did a bit of research on this recently, I came to the conclusion 
that most people dont use the ocean FLIP tank for boat interaction use 
the following technique:

1) the FLIP simulations of the boat is done in a flat FLIP tank
2) They then post deform the simulation (mesh or points) with the same 
ocean evaluate node
3) some go further and use the FLIP velocity (acceleration) of the FLIP 
as a weighting factor for how much deformation occurs
4) blending a flat ocean geo and flat FLIP is trivial as the boundaries 
always match when defomed.

 From what I could see the reasons for using a flat tank are:
  - Its much faster to sim a flat tank (no pumping in ocean evaluate 
  - The ocean FLIP tank wave velocities will destroy your nice FLIP 
splashes and blur your collisions

using this method does mean you wont get large crashing against the side 
of a object/boat, but those can probably be faked if needed

You may want to ask these guys further about the nice examples they have:


http://vimeo.com/74699403 http://vimeo.com/64140693

http://vimeo.com/88909057 http://vimeo.com/90313464



On 02/06/14 12:02, François Duchesneau wrote:
> Hello,
> I've started to work on a project involving a boat in the middle of an
> ocean. I've seen the shelf tool allows you to have the flip simulation
> match the procedural ocean surface but the renders of each one look
> different. I can adjust the color probably but what I'm missing is the
> foam generated by the ocean surface setup, this is not part of the flip
> simulation.
> Any suggestion on how to blend these two together? I thought about
> adding an alpha attribute on the flip water. Everything that is above
> the ocean surface would be one and 0 below with some blending to make
> that smooth but I wonder if there are better solutions.
> Also if anyone has recommendations on the scale of the scene for the
> flip fluid that'd be nice. In other words, should I keep  the boat not
> too big or not too small or it doesn't matter at all?
> Thanks
> Francois
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