Gourt Home::Gourt :: Scanline rendering
Scanline rendering is a rendering technique, or family of algorithms, in 3D computer graphics that works on a row-by-row basis rather than a polygon-by-polygon or pixel-by-pixel basis. All of the polygons to be rendered are first sorted by the top y coordinate at which they first appear, then each row or scan line of the image is computed using the intersection of a scan line with the polygons on the front of the sorted list, while the sorted list is updated to discard no-longer-visible polygons as the active scan line is advanced down the picture.
The asset of this method is that it is not necessary to translate the coordinates of all vertices from the main memory into the working memory—only vertices defining edges that intersect the current scan line need to be in active memory, and each vertex is read in only once. The main memory is often very slow compared to the link between the central processing unit and cache memory, and thus avoiding re-accessing vertices in main memory can provide a substantial speedup.
This kind of algorithm can be easily integrated with the Phong reflection model, the Z-buffer algorithm, and many other graphics techniques.
Scanline rendering is used by most modern graphics cards and is typically accessed by the programmer using some 3D API such as OpenGL or Direct3D.
History
The first publication of the scanline rendering technique was probably by Wylie, Romney, Evans, and Erdahl in 1967.Wylie, C, Romney, G W, Evans, D C, and Erdahl, A, "Halftone Perspective Drawings by Computer," Proc. AFIPS FJCC 1967, Vol. 31, 49
Other early developments of the scanline rendering method were by Bouknight in 1969,Bouknight W.J, "An Improved Procedure for Generation of Half-tone Computer Graphics Representation," UI, Coordinated Science Laboratory, Sept 1969 and Newell, Newell, and Sancha in 1972.Newell, M E, Newell R. G, and Sancha, T.L, "A New Approach to the Shaded Picture Problem," Proc ACM National Conf. 1972 Much of the early work on these methods was done in Ivan Sutherland's graphics group at the University of Utah, and at the Evans & Sutherland company in Salt Lake City, Utah.
References
External links
See also
"Scanline rendering"