Ragdoll character passing through rope unless thickness is increased

[josemendez]

I will send a link that contains the project files so you can take a look, I created a small scene with just a falling ragdoll, no forces applied to it, so its just a normal dead ragdoll, the problem is still there.

I will send it to that email you provided me

EDIT: Email sent

Hi,

There's a few problems going on in the scene:

- Your rope's stretching scale is set to zero. This will try and force the rope to collapse to a point, since any length x 0 = 0. This will cause collision constraints to work worse since the rope's primary goal is to set its length to zero. Typically, you always want the stretching scale to be 1, and only increase or decrease it to scale the length. If you want the rope to be stretchy, increase stretch compliance instead.

- All rigidbodies in the ragdoll weight 5 kg, so the total mass of the ragdoll is 75 kg.  Rope mass should be at least 7.5 kg per particle to keep a reasonable mass ratio (1:10) and withstand the ragdoll's weight under normal gravity acceleration.

- Rope simulation is being updated 4 times per frame (4 substeps in the ObiFixedUpdater), but rigidbody physics are only updated once at most. The result is that rigidbodies react very late to forces applied by the rope, and these do not propagate fast enough trough joints. The solution is to decrease your physics timestep to increase the frequency at which rigidbody physics is updated, and reduce the amount of substeps accordingly. This ensures that the rope and the rigidbodies are updated in sync, and that forces propagate fast enough trough all constraint trees.

These are the settings I tweaked:
- Set stretching scale to 1.
- Set substeps in ObiFixedUpdater to 1 (could use 2 if you want more stretch-resistant rope)
- Set rope blueprint resolution to 0.5.
- Set rope's mass to 10 for both control points.
- Set Unity's fixed timestep to 0.005 (that is, 0.02/4, which yields the same update frequency for ropes as 4 substeps, but also updates rigidbodies in sync).

With these settings, I can drop the ragdoll from very far above the rope and it reacts properly without any penetration.

let me know if you need further help,

kind regards