Abstract: We present a new method to implement in constant amortized time the flip operation of the so-called Greedy Flip Algorithm, an optimal algorithm to compute the visibility complex of a collection of pairwise disjoint bounded convex sets of constant complexity (disks). The method uses simple data structures and only the left-turn predicate for disks; it relies, among other things, on a sum of squares like theorem for visibility complexes stated and proved in this paper. (The sum of squares theorem for a simple arrangement of lines states that the average value of the square of the number of vertices of a face of the arrangement is bounded by a constant.)