Same model as the 3D version: gravity, quadratic drag (Cd 0.55), Magnus lift with Cl = 1/(2 + v/(Rω)) (Mehta 1985; Cross 2002), restitution plus Coulomb friction at the bounce with sliding or rolling contact. Surface values are illustrative. Left or top: top view (drag the red aim ring, the server or the receiver). Right or bottom: side view.