Hello everyone,

I have been studying Bullet solver and constraints for destructions,and run into some problems with Hard constraints.

As you can see from the attached I have 2 main problems:

1. the Hard Constraints are read by the network since it visualizing them but they stretch all the way in a weird manner. Now i searched a lot and only found this thread which i could relate to https://www.sidefx.com/forum/topic/44390/ [www.sidefx.com] . Although it sound like the problem i am having i don't understand what he means by

- “if you have deforming rbd where all motion is from deformation then you need to constraint
to the actual points and not to the rbd object itself as rbd object is not moving, the link
you are seeing is probably just visual line to center of mass”

2. the rbd packed object disappears if i set the “constraint force mixing” paramter on the hard constraint node

Any help is much much appreciated

Many Thanks
Francesco

Anyone?

I have attached a file with a new setup. To be honest, I couldn't figure out what was going on in your scene, it seemed hella complicated. How old was the tutorial you were using?

Do you just want the car to slam into the wall and break like glass? Or do you want it to deform? Do you have anim you want to preserve? The setup I attached just slams it into the wall at a constant velocity and shatters like glass.

Also, your car was below the ground plane which would break everything.

Sean

I checked out your scene file. I didn't have the time to resolve everything that was wrong with your setup, so instead I just cleaned it up and simplified it. I'd suggest letting the shelf tools do what they were designed to do, before overcomplicating your setup. Here, the only change you should need to make is how you are determining the group that breaks the constraints. If there is anything about my setup that doesn't work for you, just let me know.

Catfish and I both hitting this post together :p

Thank you guys!

Very busy this days but i will dig into them and have a look
MrCatfish I would like to deform the car, IF YOU do you have any tips on they would be very appreciated

Here is a setup for doing RBD softbody constraints using the Bullet Soft Constraint node. This is basically the Houdini demo file for soft constraints with a mod to switch to hard constraints when a certain threshold is met.

This works really well with one caveat: after the first impact, any further impacts will not re-bend the geo.

Check out the SOP solver… it switches from soft constraint to hard constraint at a certain angle threshold.


Thanks to Jeff @ SESI for help with this as well!

Sean