I've been attempting to figure out the calculations behind 3d rigid bodies in godot, and am struggling to figure out how friction is calculated (on a rigidbody with a sphere collision shape).

Through my limited experimentation, it looked to me like friction was calculated based on subtraction rather than multiplication as I usually use for kinematic bodies (that is, the linear velocity of an object was decreased by a set amount each physics frame, rather than decreasing by something like 0.98 each frame)

Does anyone know the calculations behind this? (I'm using bullet physics)