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Re: New version of mesh branch.

From: Tavmjong Bah <tavmjong@free.fr>
Date: Fri, 03 Feb 2012 13:27:15 +0100
Message-ID: <1328272035.4911.256.camel@LeLion>
To: Israel Eisenberg <owlgems@yahoo.com>
Cc: Jasper van de Gronde <th.v.d.gronde@hccnet.nl>, Cyril Concolato <Cyril.Concolato@cisra.canon.com.au>, www-svg <www-svg@w3.org>

Hi Israel,

	Thanks for sharing your interesting results! I've been studying your
email and your figures. I've got a few comments and questions. I don't
have either Illustrator or Corel Draw. 

* To edit a patch one seems to need two sets of control points. One set
to control the geometric shape of the patch and one set to control the
color spread. How does Illustrator handle this?

* Having a derivative of zero along the edge handles the case where the
color at the edge is at a maximum or minimum but we also need to
smoothly join patches where the color along the edge is in between. (And
the problem is more complicated when red, blue, and green all have
different profiles.)

* How did you generate the right side image for
bilinear_combos_compare.html? If one stares at it long enough, one can
see a grid structure, each quadrant being divided into an 8x8 grid. I am
guessing that corresponds to a simple bi-linear mesh that Illustrator
uses for export. They must use such a mesh for PostScript and PDF export
as that is all that those standards allow. Further evidence of this is
your finding that the basic patch profile is broken into linear sections
at the top. In fact, looking at final_profiles.html it looks like the
horizontal profile is broken into eight linear sections.

* I am rethinking our decision to use type 6 rather than type 7 meshes.
See: http://tavmjong.free.fr/blog/?p=361

* I am open to making SVG meshes use something like an interpolant
provided that:

	1. It doesn't complicate the syntax.
	2. There is a straight forward way of editing such meshes.
	3. There is a simple way to export them to PostScript/PDF.

					Tav
Received on Friday, 3 February 2012 12:27:50 GMT

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