Scanline Edge-flag Algorithm for Antialiasing

Abstract

In this paper, a novel algorithm for rendering antialiased 2D polygons is presented. Although such algorithms do exist, they are inefficient when comparing to non-antialiased alternatives. This has lead to a situation where the developers and the end users of the applications need to make a choice between high speed and high quality. The algorithm presented here however equals the performance of an industry standard non-antialiased polygon filling algorithm, while providing good antialiasing quality. Furthermore, the algorithm addresses the requirements of a modern 2D rendering API by supporting features such as various fill rules. Most of the research in antialiased 2D rendering has been proprietary work, and there is very little documentation about the algorithms in the literature. This paper brings an update to the situation by providing a thorough explanation of one such algorithm.