The routines which are run by DrawObjectsInList after it compares two objects, in two groups of nine. The number is made from the way the objects compare from side to side (zero to two) plus three times the way they compare from front to back (zero to two), and the second group is for a rotated view. A routine is KeepObject to keep the first object, ChooseOtherObject to swap it for the second object, or CompareObjectDepths to look at the objects more closely.