Re: [artworks] Artefacts on Artistic Lines

In article <0824e7a452.martin@xxxxxxxxxxxxxxxxxxx>, Martin Wuerthner
<lists@xxxxxxxxxxxxxxx> wrote:
> In message <52a4e513b3riscos@xxxxxxxxxxxxx> Richard Ashbery
>           <riscos@xxxxxxxxxxxxx> wrote:

> > I realise that rendering tight curves gives rise to artefacts
> > (see the heading "Avoiding problems with troublesome centre
> > lines" in the manual) but one particular Profile, the Wave ribbon
> > is particularly annoying. There is a subtle tiny line artefact
> > that appears at the junction of the "broken" paths. You are only
> > aware of it when an outline is applied.

> > is there anyway of
> > overcoming this problem?
> > Details of the problem can be seen here.....
> >
> > http://homepages.nildram.co.uk/~riscos/problems/Artefact.zip

> This tiny gap at the break point is caused by the fact that
> Artistic Lines always have a start and an end. It is not related
> to the fact that you have to open the shape to apply the Artistic
> Line because you can even close the shape again after applying it,
> and that does not make any difference.

I didn't understand that at the time but your explanation helps explain
why closing the shape doesn't have any effect.

> The computations at the
> start and the end of the line are always prone to being out by a
> fraction of a pixel, leading to a tiny gap at least on one side of
> the midpoint. As you noticed, that gap is nearly invisible unless
> you apply an outline to the Artistic Line.

> There is a relatively simple way around this: Just make sure that
> the start and the end of the line overlap slightly (but beware of
> ArtWorks auto-closing the shape, which gives you identical start
> and end positions, so there is no overlap). That will lead to a
> tiny double peak at the position where the start and the end of
> the Artistic Line meet because the two thickest parts of the line
> are no longer exactly on top of each other, but that is hardly
> noticeable, even with an outline applied.

Yes that works - if procedure is done at very high magnification then
the paths can be made to overlap relatively simply without shape
auto-closure.

Thanks for the tip Martin and for providing such an excellent variety
of profiles. I can't immediately think of anymore.

Best regards

Richard

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