Help Objects placed on top of Obi Cloth keep rotating

[LuckyPretzel]

Hi!

All iterative physics engines exhibit this problem: when there's multiple contacts affecting the same object, the order in which they're applied affects the outcome. If contacts are applied in approximately the same order every frame (and they are in most engines, to eliminate jittering that would otherwise happen if contacts were applied in a random order) there will always be a slight bias, since contacts applied last are more "important" as they can modify the result of all previously applied contacts.

Here's a video of the same effect taking place in a pile of regular rigidbodies in Unity. As you can see, some of the spheres will keep slowly rotating indefinitely when affected by multiple contacts:



In the case of cloth, it generates a lot of contacts around rigidbodies so this can get quite noticeable.

Unfortunately there's no proper solution for this, other than switching both Obi and Unity to an entirely different kind of physics solver - a direct solver. A typical hack is to freeze rigidbody rotation in place if their angular speed is below a threshold, this is often referred to as "sleeping".

kind regards,

Thanks for the response. That seems doable. The object does slightly move its position but it is not enough for me to care.

While I've got your attention, I have some further questions regarding Obi Cloth. I've noticed I can add weight/mass to the cloth via the blueprint but I don't know if I get the desired effect. I've created a video to show the real-life movement of what the cloth should achieve: https://youtube.com/shorts/XPpiNU5zTVY

Notice in the video that the net has some weight to it and that after an object sits on the net, the net doesn't completely rebound back. It remains in a bit of a sunken state. Additionally, when an object is sitting on top, the net slopes downwards towards the object. It's not just one tiny area of the net affected.

Currently, I have particle attachments for the sides, the top crossbar in the front, and the entire bottom of the net on the ground. My net object is made of 1 plane extruded in a method to retain it as a 2-manifold object. Most of the object is comprised of squares and not triangles and they are fairly big, in my opinion. 

   

I'm curious if you have any suggestions. Should I be using "seams" instead of just one object? Do I need to limit stretchiness completely and add create more slack in the net object model? Should I increase the number of squares or perhaps use triangles?

Any advice you have is appreciated. I'm mostly focused on making the net have more weight and strength without seeming like it's rigid like a box but keeping in mind performance.