Xiaolin Wu's line algorithm: Difference between revisions

Revision as of 18:21, 23 June 2005

Revision as of 05:41, 21 August 2005

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[[Bresenham's line algorithm|Bresenham's algorithm]] draws lines extremely quickly, but it cannot 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 naïve 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.

Here is [[pseudocode]] for the nearly-horizontal case (<math>\Delta x > \Delta y</math>). The extensionTo extend the algorithm to coverwork nearly-verticalfor all lines, isswap trivial,the x and lefty ascoordinates anwhen exercisenear-vertical lines appear (for thereference, see [[Bresenham's line readeralgorithm]]).

<code>