Controls whether this shape produces pre-contact and pre-continuous callbacks. This only applies to Dynamic bodies and is ignored for triggers. These are relatively expensive so disabling them can provide a significant performance benefit.
A pre-contact callback calls the PhysicsShape.callbackTarget for both shapes involved if they implement IPreContactCallback. A pre-continuous callback calls it if they implement IPreContinuousCallback. The deprecated Unity.U2D.Physics.PhysicsCallbacks.IPreSolveCallback is also driven by this switch, for targets that only implement it.