public override void Initialize(BroadPhaseEntry entryA, BroadPhaseEntry entryB) { sphereA = entryA as ConvexCollidable<SphereShape>; sphereB = entryB as ConvexCollidable<SphereShape>; if (sphereA == null || sphereB == null) { throw new Exception("Inappropriate types used to initialize pair."); } base.Initialize(entryA, entryB); }