An efficient three-point arc algorithm

For many applications a 2-D circular arc can be conveniently specified by three points that lie on the arc. Since the radius of curvature grows without bound as the three points become collinear, any practical algorithm must avoid calculating the arc´s radius or functions of the radius. An algorithm that achieves this objective is presented. It is very efficient because it uses exclusively integer arithmetic and requires only addition, subtraction, comparison, and branch operation in the inner loop.<>