| 摘要 |
Method of drawing a convex geometric figure to framebuffer storage sequentially addressable as a plurality of update arrays of determined origins which tile the framebuffer. An array comprises pixel storage sites, each specifiable by an offset from array origin, and concurrently updatable. A figure is specified as a set of directed lines, whose segments between mutual intersections comprise the figure boundary, perambulating the boundary in a single sense. The figure is tiled by a subset of the update arrays. A first array is accessed. Tests are performed to find whether the figure extends to arrays above or below the accessed array; if so the array address is stored and marked for either or both extensions. In one embodiment, a test is performed for left extension, and the steps are repeated until no further left extension is found; returning to the initial array, the steps are repeated for right extension to complete the horizontal subset. The array marked for either up or down extension is next accessed and the steps are repeated with respect to the indicated vertically adjacent array until no further extension is found in that vertical direction; the steps are repeated for the other vertical direction. The figure has been tiled. The extension test tests, with respect to the directed lines and a pair of sample pixels adjacent to the questionable array, for sidedness of each sample pixel with respect to each line. |
