Segment Scan Conversion

Given a segment in the plane and a set of grid points, or pixels, we wish to flag the set of pixels that would be an appropriate discrete rendition of the segment. Finding the set is straightforward if we are content with using floating point arithmetic, but since segment rasterization or segment scan conversion, the alternative names for the problem, is performed many times in interactive and real-time rendering, an algorithm that uses only integer arithmetic provides significant gains. This chapter discusses Sproull’s derivation [102] of Bresenham’s algorithm [21] using refactoring, or incrementally modifying a program while verifying its correctness to enhance either its efficiency or its structure.