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Transfer velocity to RBD sim, break glue with forces in 20.5


tanzola

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Hello,

I'm trying to create an outward glass shatter effect similar to the helicopter crash scene in The Matrix. So far I have rbdmaterialfracture > rbdconfigure > rbdbulletsolver and on a separate branch is a point scatter with velocity attributes I want to use to affect the glass sim, but I'm having a few issues with that (I'm a sim noob).

The first problem is that I can't get the bullet solver to read the velocity each frame. It seems to read the first frame in which there's a non-zero velocity value but stops after that. If I crank the velocity on the scatter points, it seems like mayyyybe the other frames are being brought over, but not as clearly as the first frame and the sim sometimes just stops after a few frames...

Secondly, I'd like the glass to have glue constraints and I just learned glue can't be broken with just forces, or they'd have to be manually broken. There's this tutorial that seems to be exactly what I'm looking for, but I get lost when trying to follow it in 20.5. Does anyone have any resources that could help me bridge the knowledge gap there? He breaks glue constraints in a sop solver within the bullet solver at 16:22.
https://www.youtube.com/watch?v=fzRJcGFuPXU&t=982s

Attached simplified file with my issues. Inside the bullet solver are only my best attempts... Right now I'm just trying to get the velocity transferred each frame so I turned off constraints in the rbdmaterialfracture node and gravity on the solver. It might not come through in the project file but a visualization marker for @v would show the effect I'm going for on the point scatter and also the transfer problem on the bullet solver.

Any help would be greatly appreciated - Thanks for taking a look.

Robert

customForces_v06.hiplc

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A kind sir helped me with a tip to use attribute transfer node instead of vex. Been a minute since I picked up Houdini, apparently. Updated is attached. The forces are being transferred so the issue now will be figuring out how to break constraints / have gravity affect the pieces only once they reach a force threshold, or something like that.
customForces_v09.hiplc

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