Xiaolin Wu's line algorithm: Difference between revisions

Revision as of 19:14, 16 June 2022

Revision as of 15:53, 15 December 2022

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[[Bresenham's line algorithm|Bresenham's algorithm]] draws lines extremely quickly, but it does not perform anti-aliasing. In addition, it cannot handle any cases where the line endpoints do not lie exactly on integer points of the pixel grid. A naive approach to anti-aliasing the line would take an extremely long time. Wu's algorithm is comparatively fast, but is still slower than Bresenham's algorithm. The algorithm consists of drawing pairs of pixels straddling the line, each coloured according to its distance from the line. Pixels at the line ends are handled separately. Lines less than one pixel long are 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 as 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.

==Algorithm==

<syntaxhighlight lang="pascal" line="1">

function plot(x, y, c) is

plot the pixel at (x, y) with brightness c (where 0 ≤ c ≤ 1)