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Wire collisions


bandini

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Hey, quick question...

Any way to have wire objects collide with non-sdf geometry? I am using deforming geometry, and it is taking a really long time to calculate the sdf for every frame (I need to get through about 1200 frames...). Seems like wire collisions only work with collision volumes and not regular geometry.

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Have you cached the sdf of the deforming geo?

See my post here ( http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&t=27495&highlight= ) for how to cache it in sops using isoffset if you haven't seen / done this. Depending on the object, it could long up-front to cache it out, but if you have multiple machines or even a script to run multiple houdinis locally to cache it out, it's not so bad.

Edit: No idea if it'll collide with non sdf, if you've turned off Wire/Volume collisions and it doesn't collide, then I can only assume not.

P.S. I remember back when we worked at Blur together. :)

Edited by Solitude
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Thanks, Ian!

Yep, I am familiar with that tip. Essentially the same process as what I am doing now - except I am writing the sdf to disk from DOPS during the sim, so I don't have to recalculate it later.

I remember you from the good ol' days at Blur. I was actually just looking at your vimeo page yesterday. You've been doing some awesome stuff the last few years!

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Ah, darn. Good to cache it out, but 1200 frames is still a lot, which is why I suggested doing it on a farm, or with multiple houdinis on your local machine (by doing it in sops it's frame independent).

Thanks man. I should prob post more of my RnD stuff, but I've been busy with family life. I enjoyed your cmi vids btw. There are some really good tips in there, so thanks for that. :)

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from certain version wire solver has been updated to collide with non SDFs by default (like cloth solver)

so it shouldn't require you to cache volumes

when I tested this back then, everything seemed perfect except that it was just one way (RBDs weren't influenced and that can be still the case)

there is switch on Wire solver to tun SDF collisions on/off, but default is off, but check in your scene, maybe is on, or you are using old build

Houdini 12.1.23: Updated the Wire Solver to use a new algorithm for detecting and resolving collisions...

Houdini 12.1.29: The Wire Solver now has a toggle to enable SDF collision support.

Edited by anim
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I would call it half-imporved, breaking the bidirectional compatibility is a big deal (as it was for cloth), at least they still kept SDF option for wires, but for cloth we waited 3 versions and it's still not fixed, if only bullet was fully implemented to have at least one full environment, well maybe next version :)

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