Re: Proceeding apace...
- Posted by Jeff Zeitlin <jzeitlin at CYBURBAN.COM> Mar 24, 2000
- 523 views
On Fri, 24 Mar 2000 00:00:29 -0500, simulat <simulat at INTERGATE.BC.CA> wrote: >This is pretty vague, but I remember some sort of odd/even rule that was >used for fills: >Start at the screen edge at the top >If you are inside the your fill area at the start then > start with the fill color turned on, > otherwise off. >When you hit a boundary between the fill zone and the non fill zone, toggle >the fill color. > Basically, an even number of boundary jumps means that the pixel colour is >the same as the screen edge, and an odd number of jumps means that the pixel >colour is the opposite of the screen edge. So basically, you just do a >raster scan of all the pixels, toggling the fill colour whenever the >boundary colour is encountered. Yes, I forgot what this algorithm is called, but it's one possibility that I have - the major flaw with this one is that it doesn't handle self-intersecting figures properly. A secondary flaw is one that will appear with almost any algorithm that I've seen; what if there are two overlapping figures drawn in the same color? That's the bridge that I'll fall off when I come to it... -- Jeff Zeitlin jzeitlin at cyburban.com