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Re: SVG2 - suggestion for a new path command to close a subpath smoothly

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Mon, 3 Dec 2012 12:37:12 +0100
To: www-svg@w3.org
Message-Id: <201212031237.12569.Dr.O.Hoffmann@gmx.de>
Jasper van de Gronde:
>I would suggest, though, to rethink the naming scheme. Essentially you'd
>want ANY path command to be able to close a subpath (why allow a cubic
>Bézier, but not an arc for example). So if they all get letters, that's
>a lot of letters. Instead, I would suggest letting an author "flag" when
>a path command should close a subpath.

With a cubic curve you can close the path smoothly, because you have
enough parameters, two control points. For example with a quadratic path
you have only one control point, therefore typically the path cannot be
closed smoothly. With elliptical arcs - does it work in general? If you have
multiple arc commands following each other with different half axis and
alignments, are you sure you can close such arc paths smoothly with only one 
arc command? Currently we do not even have something corresponding to 
S and T for the A command to connect different elliptical arc segments
smoothly.

For not degenerated cubic path data it is simple to provide a formula to close
the path smoothly. We have to show, how to do this for other data or even
for mixed notations, if we need a general solution.

Currently we do not even have a smooth connection for Q followed by S
or C followed by T etc - this would be possible as well, but not backwards
compatible to the current rules.


Olaf
Received on Monday, 3 December 2012 11:38:46 GMT

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