Posted Sep 27, 2009 21:17 UTC (Sun) by oak (subscriber, #2786)
Parent article: LPC: 25 years of X
> As an added bonus, the combination of ellipses and circular pens
requires the evaluation of quartic equations.
Nonsense. You can get the closest and furthest points on a circle on an
ellipse arc with just multiplication and addion and do the drawing based
on that. For an example, see the "generic_circle.c" file in http://koti.mbnet.fi/tammat/src/wws_1.4.5.tar.gz
(X lets one to specify ellipses with width and height, W only by radius.
To get the W code to handle also half-pixel radiuses, one would need to
shift the values by one bit. WWS code was later adopted also for
MicroWindows / Nano-X window system.)