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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.
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.▼
==Pseudocode implementation==
Here is [[pseudocode]] for the nearly-horizontal case (<math>\Delta x > \Delta y</math>). To extend the algorithm to work for all lines, swap the x and y coordinates when near-vertical lines appear (for reference, see [[Bresenham's line algorithm]]).
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'''end function'''
</code>
▲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.
==References==
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