FLIP Fluid - Mantra Velocity Mesh Pass

[Ahmed Saady]

Sure, here's a quick implementation. Vorticity is not calculated by default, so we need to add that to the solver inside the dopnet. First, a Gas Match Field DOP to create a temporary vorticity vector field that matches the vel field, and then a Gas Analysis DOP to calculate the curl of the vel field. Within fluidtank_fluid, vorticity is added to the list of volumes being imported to sopland, and the vorticity vectors are transferred to the surface points. What we want to see in the end is the magnitude of the vectors, so there is a quickie Attribute VOP SOP to do that.

 

As above, the vorticity is bound to a vex variable within the material, and an extra imageplane is added to the ROP.

thank you so much for the hip file i will look at it.

i did this first test hope you like it guys

https://vimeo.com/117956207

[mikkelm2]

Naming the channels "RGB A" is not a bad idea at all, i will try! Thanks Houdini master!

 

I did a quick work-around to export it, i was able to import my .exr file into houdini and export the speed channel as a .png sequence to after effects.

But for the png sequence to work and show the speed channel in after effects, i had to set it as my "Color plane" Here's an image so you can see - The speed pass is for some reason called "1" btw.

 

 

 

Here's a quick render test from the .hip file you posted.

 

 

AhmedSaady, you mentioned this: "I think you are getting this high white value bcoz you did not calculation your vel , so use your length to calculate it in vop sop , then i think you will read it in Mentra correctly."

Is the velocity not being caulculated? Which vop too add to the length, to calculate velocity? I want to fix the speed gradient, is way to white like you said.. 

[mikkelm2]

Nice work on the shark shot AhmedSaady!

[andmotion]

Hey,

 

I am new to H16 so my question might sound not wise  anyway I am trying get velocity pass from Ocean Flat Tank and the result is like on the picture I attached. 

How to avoid these  white lines along the extended  Ocean surface?

For any info on it I will be massively thankful

and

 

[PalTopin]

1 hour ago, andmotion said:

Hey,

 

I am new to H16 so my question might sound not wise  anyway I am trying get velocity pass from Ocean Flat Tank and the result is like on the picture I attached. 

How to avoid these  white lines along the extended  Ocean surface?

For any info on it I will be massively thankful

and

 

I think those extended lines come from the "flattening" option in the Particle surface fluid SOP.

[andmotion]

33 minutes ago, PalTopin said:

I think those extended lines come from the "flattening" option in the Particle surface fluid SOP.

Hey,

Yes they do come from "flattening" option, I think I might render velocity pass with that option turn off but that's lead me to do rendering process twice. One for whole

ocean surface and one just for velocity pass which I would like to avoid actually , hmmmm.

There is also option to increase division in particlefluidsurface SOP so that could potentially solved the issue but at caching time cost I guess 

Edited August 16, 2017 by andmotion

[andmotion]

I did a test with higher division and the result is the same.....

 

[PalTopin]

25 minutes ago, andmotion said:

I did a test with higher division and the result is the same.....

 

You could try check the mask options and mask the velocity, also in the flattening you could use circle shape for the fall off between the motion and the extended mesh.

Also you may need to make the flat tank bigger, so you can have a nice looking fall off.

Edited August 16, 2017 by PalTopin

[andmotion]

16 hours ago, PalTopin said:

You could try check the mask options and mask the velocity, also in the flattening you could use circle shape for the fall off between the motion and the extended mesh.

Also you may need to make the flat tank bigger, so you can have a nice looking fall off.

Thanks PalTopin 

I will give it a try today .

[Arch]

Hi everyone ! 

I tried to call velocity in the shader with both parameter node and three nodes of eetu (bind+lenght+export bind) but nothing in render...
Method has changed in H16?

EDIT: My bad ! I just didn't place my nodes in the right place 
 

Edited October 27, 2017 by Arch
resolved