Using a vopsop to effect surface normals or velocity to create churnin

[zinj]

Hello

 

I've been struggling with this and not getting the correct effects.

 

As we all know, there are plenty of rising ships out of flip fluid sims on vimeo.

 

The part i can't figure out is before the ship is emerging, normals or velocity force is driving the flip fluid to churn and boil right

before the ship emerges.

 

What I do know is, before I convert toe VDB for velocity collisions, i have the time blend node and trail sop to compute velocity setup. I want top create a vopsop before the trail node to effect the velocity or normals of ship so that it creates a force to churn the fluid right before ship emerges. I think that is how it should work but...

 

Can someone please show me example how to do this?

 

Thanks!

 

 

[nick2970]

I found this useful for a quick guide on how to get velocity from point normals with a vopsop

 

http://cgterminal.com/2013/09/08/houdini-creating-boat-engines-using-pump-tutorial/

 

Cheers, Nick

[zinj]

No that doesn't really work because I would have to bring that into with a fluid solver and it takes forever to bake that out in which

I"m using a complex model.  

 

I need to do this in a vopsop ... combine velocity from the trail velocity of the animation of the ship, with a custom type of velocity (using N)

and combine the two so that when the ship is starting to rise, the fluid starts to boil in the outline of the ship, not this smooth elastic looking hump

which is totally unnatural looking.  I appreciate the link though!

 

Here's the file, just use some other object in place of the ship geo.

 

 

battleship_v002b.hip

Edited July 3, 2014 by zinj

[3iart]

Diego, I dont have houdini in front of me right now so I am stabbing in the dark and maybe confusing the issue, but that has never stopped me before.

 

but what I normaly do is first normalize the normals, then plug that into a vector4 anti-aliased noise then plug that into v. t should be your 4th argument. 

 

If that doesnt make sense let me know and I will try and get in front of a Houdini box when I can.

[wateryfield]

No that doesn't really work because I would have to bring that into with a fluid solver and it takes forever to bake that out in which

I"m using a complex model.  

 

I need to do this in a vopsop ... combine velocity from the trail velocity of the animation of the ship, with a custom type of velocity (using N)

and combine the two so that when the ship is starting to rise, the fluid starts to boil in the outline of the ship, not this smooth elastic looking hump

which is totally unnatural looking.  I appreciate the link though!

 

Here's the file, just use some other object in place of the ship geo.

You forget upload the  Titan class II cargo ship flying.obj 

[zinj]

Okay, its seems what I need to do is use Smoke from Obj and apply that as pump in addition to the OBJ Velocity from the VDB piped into the Flipsolver!