  We use circle-packing methods to generate quadrilateral meshes for polygonal
domains, with guaranteed bounds both on the quality and the number of elements.
We show that these methods can generate meshes of several types: (1) the
elements form the cells of a Voronoi diagram, (2) all elements have two
opposite right angles, (3) all elements are kites, or (4) all angles are at
most 120 degrees. In each case the total number of elements is O(n), where n is
the number of input vertices.
