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DOPs penetration


blackchicken

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Hello I just test new setup on very simple scene, and I found some penetration problem with 2 cubes.How help houdini not to penetrate between objects? Look at the wery wery simple scene. Resolve penetration didnt help, more sampling samles too. In much much more complex scene about 1000 RBD objects that will be close to camera should be big problem. Another thing is noise of some rbd fractured objects. It is possible like in maya bake simulation and clean animation curves by hand? In chops import cuves specific RBD fractured peace, clean it and then back to scene? (delete dynamic peace, copy static and add transforms from chops and add it to good simulated objects). Thanks a lot for help...BC....

boxes.hip

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  • 3 years later...

Hi,

since the penetration issue is fixed now I wanted to address the second question about the "noise" in fracture objects.

I think you are referring to the small movements you get when the pieces start to come to still stand.

Since the pieces are either pre fractured or only fractured on one frame you should not get geometry flickering from the sim other then tiny movements towards the end of the simulation.

The simply solution for that is the RBD Auto freeze node in dops.(http://www.sidefx.co...p/rbdautofreeze)

it takes a threshold of velocity and checks your pieces against it.

If the vel is above that threshold it will make is "freezable" which means that it will now check it against a second threshold that you define and when its below that it will "freeze" the movement of the piece.

It is a very handy node to use in almost every RBD simulation.

Cheers,

Juri

Edited by JuriBryan
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I find that chaotic pieces are generally a result of poorly calculated mass/density and/or friction. Sometimes, a high collision padding will cause smaller pieces to not get any collision geometry, causing them to flip around and go crazy. Sub stepping can help a bit too, but you shouldn't need more than a few subsets on the dop network, and maybe between 10-20 on the bullet solver. Also, if your using bullet, it's kind of in it's nature to be crazy. Auto freeze can help a bit as mentioned above. Are you working in real world scale? Maybe try lowering the split impulse on the bullet solver also.

-just realized how old this thread is...

Edited by nFrame
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