# Re: Elliptical Arc Question

From: Goessner / MecXpert <goessner@mecxpert.de>
Date: Sat, 27 Apr 2002 17:17:02 +0200
Message-ID: <001101c1edfe\$964317a0\$fe78a8c0@alpha>
To: "Dean Jackson" <dean@w3.org>, "Kevin Lindsey" <kevlindev@kevlindev.com>
Cc: <www-svg@w3.org>
```kevin, dean,

> > Section F.6.2 of the SVG 1.0 Specification effectively states that an
> > elliptical arc whose endpoints, (x1,y1) and (x2, y2), are identical will
> > not be rendered.  This behavior surprised me since I expected the
> > following cases:
> >
> >     large-arc-flag=0, sweep-flag=0|1, nothing rendered (per the spec)
> >     large-arc-flag=1, sweep-flag=0, a complete circle is rendered to the
> > right of (x1,y1)
> >     large-arc-flag=1, sweep-flag=1, a complete circle is rendered to the
> > left of (x1,y1)
> >
> > I was curious if these cases were considered and, if so, why they were
> > rejected.
>
> Kevin,
>
> I came across this problem recently, but forgot about it before
> writing it down somewhere as a question to ask the WG. I'll raise
> this question now. Expect an answer here sometime next week.
>
> Dean

.. good question, kevin. i also stumbled over this some time ago. since you
can create a crew of circles through a given point with given radius,
rendering them right or left to the point (x1,y1) is only a proposal .. but
a good one .. and a far better solution than simply not rendering the arc.
another solution might be to use the path's current directionality (s. spec.
app. F5, markers, directionality and zero length path segments) so, that the
circle is tangential to the path's current tangent in that point.

--
stefan
```
Received on Saturday, 27 April 2002 11:12:57 UTC

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