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supremeoh

rbd sinking

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Hey, how's it going? I was wondering if anyone can give me any tips on Rbd where once the sim begins the RBD object sinks into the ground a bit. How can i prevent this? I'm placing it as close to the floor already. But I still get that moment where it sinks into the ground a bit as the sim begins. And its quite noticeable.  In my setup its just a torus with vdbFromPolygon RBD object. thanks!

 

hip file attached

 

floodtest_001.hipnc

Edited by supremeoh

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You probably need to check the mesh that gets brought in the DOP...from what you said you are using vdbFromPolygon..you need to convert that back to Houdini volume and read that in DOPs...

If you post your hip file we can much more easily troubleshoot it..

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Its in the beginning stages but hip files attached now. I'm trying to do a large scale flood test crashing into multiple objects. Do you think the scale is correct? thanks a lot! 

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You didn't include your source triangle geometry.

 

RBD(torus) is not sinking. It's being pulled down by gravity.

 

If you don't want that to happen remove gravity from it. You can apply mask or can animate activation of gravity on torus.  

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VDB volumes work fine in DOPs for collision purpose with both flip and rbd solver. No need to convert those to Houdini volumes.

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You should have feed VDB volume to RBD's Poxy Voulme field rather than in SOP path.

May be it happens because you used shelf tool with display flag on VDB. Before using shelf tool you need to set display flag upstream on polygon geometry (in your scene xform1).

Or create vdbfrompolygon in separate branch after sending polygon geometry to DOPs.

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VDB volumes work fine in DOPs for collision purpose with both flip and rbd solver. No need to convert those to Houdini volumes.

 

Just for clarity, DOPs converts all VDBs to Houdini Volumes internally; VDBs aren't used directly by any of the Houdini Solvers (yet). But the conversion is really fast/efficient, and in my limited experience I've found it's always easier to get good collision geom with VDB -> Proxy Volumes.

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Just for clarity, DOPs converts all VDBs to Houdini Volumes internally; VDBs aren't used directly by any of the Houdini Solvers (yet). But the conversion is really fast/efficient, and in my limited experience I've found it's always easier to get good collision geom with VDB -> Proxy Volumes.

Yes, I should have mentioned that.

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Thanks for all the help guys! So I changed all the VDB Proxy like you said. For VDBfromPolygons for the exterior and interior band voxels should it be a low or high number? Should the box be tightly around the torus objects ? I'm still trying to figure out the mask so that torus doesn't drop into the floor when simulation begins. 

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Can't check your file.

Did you set Feedback Scale to larger value something like 1000. According to documentation 1000 works well with RDBs. 

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Just opened your file up and the fluid is pushing the torus objects around just fine. Could be a version issue maybe? I am using 14.0.201.13 here.

-Ryan

Edited by rbowden

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