Applying moving constraints with Bullet solver

[freejonah]

Houdini community,

Hoping to get some advice with something that has me stumped. I've attached a hip file to demonstrate the situation.

I'm attempting to create a controlled shatter on a moving object using the Bullet_Solver sop. I've gotten as far as animating my pieces to be active or inactive so they release from the animated object as required, collide, etc.

My big issue is how to make use of constraints here. I want to have glue constraints keeping things sticking together in a more interesting way but I can't seem to get them to do anything. Should the constraints themselves be moving or static? Does that matter? Should I create them a different way?

Any help would be appreciated. Thank you.

moving_constraints.hip

[Pirminus]

Hey,

 

I did take a look at your file, I think the problem was you did not input the constraints to your sop solver. So I took the rest geo before the point deform, unpacked it, created the constraints and plugged them into the solver, now it does not fall apart. Don't know if this is exactly what you are looking for. 

moving_constraints_reworked.hiplc

[freejonah]

Thanks Pirminus. I do actually want the fragments to fall. I just want them to stick together a bit before doing so. Kind of like crash glass for a windshield.

I tinkered with it a bit with some guidance from you and some others. I have the constraints wired properly I think and also I realized my name attribute needed to be promoted. The problem is still that I can't get the behavior I want. The constraints either connect everything together into a big garlic knot or they do nothing.

Attached is a new hip file with some adjustments. Still not great but better. Any advice on settings and tricks would be appreciated.

 

moving_constraints2.hip

[Pirminus]

Hey there,

 

ok so I changed some things again

I set the Constraints back to Glue and attached basically alsmost the same thing you had with the activate stuff on your rbd pieces. It's just creating a group and deleting the constraints with a blast node. On a fresh rbdbulletsolver I just checked 'Overwrite with Sop' and fed the blast node in the VEXpression SOP Path. Now your constraints break when the sphere touches and delets some of the constraints on the rest frame. Now you can go crazy and delete them in any order you want. Hope this helps.

 

Cheers

Pirmin

moving_constraints3.hiplc

Edited July 18, 2021 by Pirminus