Xiaolin Wu's line algorithm: Difference between revisions

Revision as of 06:15, 7 December 2012

Revision as of 09:08, 14 December 2012

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'''Xiaolin Wu's line algorithm''' is an [[algorithm]] for line [[Spatial anti-aliasing|antialiasing]], which was presented in the article ''An Efficient Antialiasing Technique'' in the July 1991 issue of ''[[Computer Graphics]]'', as well as in the article ''Fast Antialiasing'' in the June 1992 issue of ''[[Dr. Dobb's Journal]]''.

[[Bresenham's line algorithm|Bresenham's algorithm]] draws lines extremely quickly, but it does not perform anti-aliasing. In addition, it cannot handle the case where the line endpoints do not lie exactly on integer points of the pixel grid. A naïvenaive approach to anti-aliasing the line would take an extremely long time, but Wu's algorithm is quite fast (it is still slower than Bresenham's, though). The basis of the algorithm is to draw pairs of pixels straddling the line, coloured according to proximity. Pixels at the line ends are handled separately. Lines less than one pixel long should be handled as a special case.

An extension to the algorithm for circle drawing was presented by Xiaolin Wu in the book ''[[Graphics Gems]] II''. Just like the line drawing algorithm is a replacement for Bresenham's line drawing algorithm, the circle drawing algorithm is a replacement for Bresenham's circle drawing algorithm.