Re: [AGG] Outline bug

[Maxim S. <mcs...@ya...>]

> I have played quite a bit with AGG these last weeks and I have come
> up with following problem: when painting wide outlines of paths with
> sharp edges, AGG somehow messes up. I hope the attached GIF file
> shows the problem clearly enough.
> 
> Have you any idea of how this could be fixed?

Well, it's not that trivial. I honestly don't know a simple solution of that.
The stroke converter is the simplest and the fastest one, but it can produce
some defects. The defects are rooted from self-intersecting polygons that
appear wnen working with very sharp angles and wide strokes:

http://www.antigrain.com/img/self_intersections.gif

These kinds of defects are eliminated when rendering if you use the non-zero
fill rule. However, in more complex cases there can be more than two
self-intersecting areas overlapping each other. As a result we can have some
holes even with non-zero filling.

Of course, it's possible to get rid of self-intersections analytically, but
it'll be much more complex (and much slower) algorithm. Ideally, we need to
calculate the Minkowsky Sum. Anyway, it should be a separate converter that
works slower, but produces perfect result.

> PS: Last message I saw on the list was dated Dec. 23 2003, is this
>     correct or do I somehow miss messages?

I just took a little break. 
"Anyone can take a break, but noone can tell how long it will last" :-)

McSeem


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