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Re: [Inkscape-devel] Markers and angle bisectors

From: David Turner <novalis@novalis.org>
Date: Fri, 06 Aug 2004 16:15:27 -0400
To: bulia byak <buliabyak@gmail.com>
Cc: www-svg@w3.org, inkscape-devel@lists.sourceforge.net
Message-Id: <1091823327.23804.12058.camel@banks>
On Fri, 2004-08-06 at 15:34, bulia byak wrote:
> > A rule which accomplishes this is: If the clockwise angle from the
> > incoming vector to the outgoing vector is greater than 180%, use the
> > outer angle bisector, else use the inner angle bisector.  Incoming
> > vectors are those which are closer to the start of the path.
> 
> I'm not sure I completely understand your intent. If I add mid-markers
> to the path in your example, they both look in one direction. I think
> this is both correct and logical, and Batik/Adobe render them exactly
> the same. So I don't think we need to change anything here.

Inkscape currently does the right thing sometimes (by pure luck, more or
less) -- that particular example does not illustrate a flaw in Inkscape,
but in the SVG spec.  An example illustrating two errors in Inkscape's
behavior is attached.

On the top path, it looks like the marker's direction is controlled by
the wrong control point of the bezier.  

The bottom two paths demonstrate that Inkscape computes angles
incorrectly -- it averages the tangent vectors of the incoming and
outgoing segments, rather than averaging their angles.



marker-dir.svg
(image/svg attachment: marker-dir.svg)

Received on Friday, 6 August 2004 15:55:49 UTC

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