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Granular Sheet - Moving Pin Constraints

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Hey everyone,

after unsuccessfully scouring the web and the two big Houdini forums I finally brought myself to asking directly. I'm currently trying to animate a sheet of cloth using a granular sheet since the FEM approach is just excruciatingly slow. I've found three methods for pinning parts of the granular sheet in position (@stuck, @mass = 0, @targetP) but I wasn't able to find a use either of these methods for an animated pin constraint. I'm obviously still not really proficient in Houdini since this problem has me completely stumped. So if any of you lovely people would point me in the right direction, I'd be immensely grateful.

Thanks in advance!

*edit: After searching some more, I came across this thread: 

While the file attached to the thread works when I play it, when I try to copy that setup into my scene, it just refuses to work, even though the @targetP gets updated. Obviously, I'm doing something wrong but even comparing the node settings side by side I can't for the life of me figure out what that something is.

*edit #2: Okay, I finally figured it out. I didn't realize that the sop solver node is empty by default and you have to create the sop structure to update every frame by yourself. Now that I've figured that out it is perfectly reasonable, I just didn't think of that for quite some time.


Edited by Kaprolactam

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Yes, it works. I've got several other things to figure out but this, fortunately, isn't one of them anymore. And yes, I knew that the sop solver would have to update the targetP every frame, it just didn't dawn on me that I have to dive inside the solver until I noticed that it doesn't have that little icon of a closed padlock next to it. After that, it was blindingly obvious. Oh well, you live and learn.

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