tanzola Posted March 31 Share Posted March 31 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 Quote Link to comment Share on other sites More sharing options...
tanzola Posted April 1 Author Share Posted April 1 In the dopnet > sop solver > wrangle, it seems the nearpoints function only actually finds neighbors of point 0 for some reason... That might actually be my issue rather than not reading each frame. Quote Link to comment Share on other sites More sharing options...
tanzola Posted April 2 Author Share Posted April 2 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 Quote Link to comment Share on other sites More sharing options...
Atom Posted April 3 Share Posted April 3 You can keyframe time scale. Applying more force will auto-break the constraints. ap_customForces_v09.hiplc Quote Link to comment Share on other sites More sharing options...
tanzola Posted April 3 Author Share Posted April 3 Hey Atom, thanks for checking out my project. I'm not exactly sure what the secret sauce is here but to me it seems like there's no longer any constraint geometry, even when turning off the waveforce node and gravity on the bullet solver. I'm imagining my goal as something like if waveforce > threshold, break constraint, so I'd like to keep the constraints until waveforce breaks them, if possible. And maybe this is too much to even say but another component of this will be the lack of ground and not having gravity affect the pieces until the constraints are broken, but maybe that part will come for free after the constraints, idk. Appreciate it! Quote Link to comment Share on other sites More sharing options...
Atom Posted April 3 Share Posted April 3 Maybe you could reverse engineer something like this. ap_hard_glue_wall_breaking_040325.hiplc Quote Link to comment Share on other sites More sharing options...
Atom Posted April 3 Share Posted April 3 Here's the same scene after playing with a few parameters. Lower density and gravity. Also played with the glue release control. ap_hard_glue_wall_breaking-2_040325.hiplc Quote Link to comment Share on other sites More sharing options...
tanzola Posted April 3 Author Share Posted April 3 I appreciate your confidence in me - and the suggestions. I need to spend some serious time learning about constraints and dops, however... I think I just found a solution that may work in this case. Took me a while but I figured out a way to manipulate the constraint geo, which is with a "sop solver (constraint geometry)" node. Brought in the point scatter the same way as with the geo sop solver to get the wave force, then the constraint prims are deleted if the waveforce is above a certain value. Not sure if this is the best way to do it but since it seems to be working, I'd consider this a success. Thank you! customForces_v12.hiplc 1 Quote Link to comment Share on other sites More sharing options...
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