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Re: Comments on SVG 2 Gradients

From: Tavmjong Bah <tavmjong@free.fr>
Date: Thu, 08 Dec 2011 20:27:06 +0100
Message-ID: <1323372426.18668.179.camel@LeLion>
To: Cyril Concolato <Cyril.Concolato@cisra.canon.com.au>
Cc: "SVG WG (public-svg-wg@w3.org)" <public-svg-wg@w3.org>
On Thu, 2011-12-08 at 05:47 +0000, Cyril Concolato wrote:
> Hi SVG WG members,
> The next item to be discussed on the SVG 2 Requirements list is
> Gradients. I’ve a made a small page
> (http://www.w3.org/Graphics/SVG/WG/wiki/SVG2GradientsComments)
> describing some comments that I would like to discuss, possibly if we
> have time during the next telcon. Let me know if you have comments.

Hi Cyril,

	I've seen the same problem you point out with some of the drawings I've
made. It shows up when one has a large change in color as your black and
white example shows. The problem can also be seen with the existing SVG
linear and radial gradients. I've been planning on adding tensor meshes
to my version of Inkscape to see if moving the tensor handles can
minimize the effect.

	You point out the problem can be seen to some extent with my color
conical gradient example. This is the exact same problem as one has with
linear and radial gradients. I verified this when I first saw the
problem and wanted to know if it was a bug in the Cairo implementation
or if it was inherent to linear/radial/Coons patch mesh gradients.

	The paper you refer to is interesting, especially the mesh optimization
part (from Inkscape's point of view). However, I wonder in practice if
the drawings would appear much different if the meshes were simply Coons
Patch meshes. For the most part, all the meshes have small changes in
color where the problem you've pointed out would not be so apparent.

	For me, the question becomes: do we want to specify the more
complicated Ferguson meshes (or something similar) in the SVG spec or
stay with the more simpler (and "standard") Coons Patch/Tensor Patch
meshes and let the authoring software take care of any problems (like
Illustrator does when exporting to PDF).

Received on Thursday, 8 December 2011 19:27:52 UTC

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