Re: Overlap removal

Since extrema and no-overlap are file format requirements,
why not make it a default operation before converting to
a font file?

On 29-06-14 15:24, [email protected] wrote:
> On Sun, 29 Jun 2014, Kristof Bastiaensen wrote:
>> "Locating all the intersections between two Bezier curves is a difficult
>> general problem, because of the variety of degenerate cases."
>>
>> This is simply not true, there aren't a lot of degenerate cases to handle.
> I don't think locating the intersections between two Bezier segments, or
> even between one segment and itself, is the hard part of the
> overlap-removal problem.  It doesn't seem to be where FontForge's existing
> code has trouble, and there are well-known standard techniques.  The hard
> part seems to be the bookkeeping of which segments should and shouldn't be
> included in the output, when segments should be split, and so on, in order
> to produce topologically valid output and not loop infinitely.  This is
> also easy in principle, but the existing code does not do it correctly.
>
> While we're talking about this kind of thing, "add extrema" could use a
> look too... it is a file format requirement, and again dead easy in
> principle, but due to numeric precision issues (especially after rounding
> to integer coordinates) it's very difficult to generate output that *both*
> has integer coordinates *and* points at all extrema; and some earlier
> versions were capable of going into infinite loops during "add extrema"
> (again because of numeric precision: after finding an extremum and
> splitting curves to add it, the new curves would have extrema elsewhere)
> although I haven't seen an infinite loop there recently.


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