I download unofficial 3.1 and make simple scene with RigidBody. I move RigidBody on terrain with translate (Vector3).
And i download 2.1.5 Stable and make simple scene with RigidBody.
Physycs settitngs is default.
In 3.1 i see jitter RigidBody, in 2.1.5 moving is smooth and good
Is is bug in Godot3 Rigidbody physycs?
How to smooth moving RigidBody on terrain in Godot 3?