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Bernardo

Houdini fluid sim export to blender

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Hi everyone! I am doing a fluid simulation in houdini that I then want to export in blender. I already achieved something, but I think I am in need of a couple of advices and I hope someone can help me here. 

This is the result so far after I exported all the elements in blender:

VA_WaveTest_Houdini_002.mp4

Question1: how do I export whitewater separating spray from the foam and the bubbles? I am exporting whitewater using alembic to blender and it works great... However at the moment it's all in the same file, foam, bubbles and spray. While the former two I think can be rendered together, I would like to have the spray on a separate alembic or even better VDB so I can render it as a volume. 
How can I do so? Here you can see my current setup... I see that in the whitewater_IMPORT node group houdini extract some volume info from the whitewater particles so I tried to export those as a VDB but once I imported in blender I think that ALL the whitewater has been exported in the VDB not only the spray. I guess I would have to isolate some part of the whitewater based on some attribute, but I am a bit lost here... Can anyone give me a hand please? 

Question2: Is there a way to automate all the steps of the simulation caching process? So far I've been doing R&D but when the time for the final simulation come I would like to automate a bit the baking process. At the moment I cache in sequence: flip sim, whitewater sim, mesh and then I export the mesh and the white water to VDB. I would like to know if I can create some kind of BATCH of those actions so that I can leave the computer to crunch overnight and it will automatically start the next step after finishing baking the previous one. 

Thanks everyone for any help in advance! :)

Whitewater_IMPORT.png

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some update about the batch baking: I think what I need to look into is TOP networks as it seems to be a tool to execute several tasks automatically. I still need to figure out how it works exactly but I managed to take my first steps into it and I used a ROPgeomentry node to baked the flip simulation in the TOP network. Things worked as I got my sim files on the disk and those work correctly. The only problem is that baking this way seems to be incredibly slow compared to the normal file cache node in the fluid network: baking the same 120 frames, with the same settings took 2 minutes baking from the cache node, while it took over 40 in the top network. I think I am obviously doing something wrong... any help here please? 



 

TopNetwork.png

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Turn on "all frames in one batch" on your top. If you don't have this turned on your sim will have to compute preroll for every frame it's processing

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Hey Doc, thanks for your reply! Yes that worked, yesterday I already found out and I was coming to share the info here! Moreover I think I was using the wrong ROP... I think the right one is ROPfetch, not ROPgeometry. 

Moreover, I think that maybe hqueue is better suited for what I need to do, since I don't need variations, and hqueue seems more complete when it comes to queuing jobs, as it gives info about the time for each job and houdini runs in the background. 

I also managed to understand how to delete the spray particles from the whitewater: I used a delete node, in expression mode with the expression "@spray>.1"

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3 hours ago, Bernardo said:

as it gives info about the time for each job and houdini runs in the background

 

TOPs do the same. You just have to set up some nodes yourself to print out the job info.

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2 hours ago, dleonhardt said:

TOPs do the same. You just have to set up some nodes yourself to print out the job info.

that's good to know... can you also run the sims in the background with TOPs? running them while houdini is running with the GUI doesn't sound ideal

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