[GodotPhysics] Thin collision shapes cause resting RigidBodies to shake at low physics FPS

[kubecz3k]

Godot version

c41e4b1 (4.x)

System information

Ubuntu 22.04

Issue description

By lowering physic tick rate to 30 I was able to observe that some bodies in the project I'm working on are trapped in kind of endless feedback loop and they are unable to rest:

Probably worth to mention, I did similar test on Godot 3 and I was unable to reproduce similar behavior on mass = 1000 (weight 9800) with physic tick rate at 10 (on gif tick rate=20, mass = 100kg)

Steps to reproduce

1. Lower project physics tick rate to 20
2. Create new scene with Static body as a floor
3. Create 3D RigidBody with a cube as a collider with default size, increase its mass to 100
4. Put the cube above the ground
5. Give it some angular velocity, experiment with various values
6. You should be able to observe that the cube sometimes refuses to rest

Minimal reproduction project

rigid_shake.zip

[kubecz3k]

cc @pouleyKetchoupp

[Calinou]

I can confirm this on 4.0.alpha 1b057e1.

This is caused by the floor's collision shape being too thin (0.1 units). Making it 1 unit instead solves the issue on my end. The issue is therefore similar to #9071, except it's happening with individual contacts rather than the entire body.

Probably worth to mention, I did similar test on Godot 3 and I was unable to reproduce similar behavior on mass = 1000 (weight 9800) with physic tick rate at 10 (on gif tick rate=20, mass = 100kg)

Can you test this with the 3D physics engine set to GodotPhysics in 3.x? Also, please upload the minimal reproduction project for Godot 3.x.

cc @pouleyKetchoupp

He's no longer involved in Godot, so please don't ping him in the future.

[kubecz3k]

Even taking into account new information from @Calinou I'm unable to reproduce in 3.4.4.
Attaching 3.4.4 project if anyone feels like experimenting ShakyCollisionTest.zip (again not a reproduction since can't reproduce)

[rburing]

I can reproduce it in 3.5-rc6 and also 3.4.4, both with Godot Physics. It doesn't happen frequently though. Opening multiple Godot processes seems to reproduce it more quickly, but I was also able to reproduce it in a single process. The above ShakyCollisionTest.zip has the physics engine set to Bullet. I also wasn't able to reproduce it with Bullet.