Help cloth passthrough

[josemendez]

Thanks for the clarification. On another look it happens because of "pass through".

Yes, I understand. I think not having 2-way is acceptable for me. I can restrict the movement of the forceps.

2-way means the forceps can apply forces on the cloth, and the cloth can apply forces back to restrict forceps movement. This is what happens in the real world when you pick an object: you apply a force to it, and it applies a force back on you. For instance if you push a door, your hand moves forward and the door opens, but once it's fully opened you can't continue pushing it and your hand will not move past/trough the door, no matter how much you push.

Drawing a parallel to your current situation, the hand in this example would simply pass trough the door since it's ignoring the force the door is applying on it.

Most VR games use a two-way coupling approach so that you can't (for instance) lift very heavy objects or simply force your hands past walls or other obstacles:
You could restrict forceps movement any other way without relying on physics, but manually determining when and how to restrict movement can be *very* tricky.

Checking my understanding here: pass through happens when the distance between cloth particles exceeds collider size?
That is why larger colliders don't pass through. Also curved colliders seem to work better, I think for the same reason.

Correct. When you pull the cloth, at first particles move normally and there's not much tension in the links between them. If you continue pulling, at some point tension starts to become too much and particles start separating from each other, opening gaps in between them trough which colliders can pass. The size of the gap vs the size of the collider determines whether the collider can pass or not.

In a two-way coupled setup, as tension increases, cloth starts to apply a force on the forceps that's equal to the force you're applying to the cloth while pulling. Once both forces cancel out each other, neither the cloth or the forceps are able to move.

If so, then if I am trying to model a very compliant elastic sheet, and I use a small collider to deform it, then there is a high risk that pass through once the particles separate enough?

In this case, surface collisions will help. Surface collisions improve spatial sampling, as long as the tension forces involved aren't large (and they won't be because cloth is compliant) collisions will work fine.

Changing the mass helps. There is less pass through, instead the cloth jitters when it is tense.
Would you mind explaining how the relative mass works on this pass through issue?

Changing the mass will not really help much. In this case, it just changes tension distribution: will affect how particles are distributed when under a lot of tension, but not in any meaningful/controllable way.

If the forceps were a rigidbody mass would work just like it does in the real world: the relative mass of two objects determines how energy is distributed when they interact. The larger the mass of the cloth is compared to the mass of the forceps, the harder it would be to pull from it. Imho, this would be the ideal setup in your case.

kind regards,