1. A computer program product, stored in computer readable memory and executable by a data processing system, for rendering a graphical polygon, said polygon being defined by connecting edges surrounding a polygon interior, comprising: means for computing a plurality of spans, each span including a portion of the polygon interior and at least two polygon edge points on each of at lest two edges of the polygon, including computing which of the at least two polygon edge points of the span are to be rendered; means for computing at least one color value for each computed span; and means for rendering said spans on a display using said computer color values including only polygon edge points computed to be rendered.