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RE: patternTransform -- and toroidal wraps

From: David Dailey <ddailey@zoominternet.net>
Date: Tue, 4 Oct 2011 07:31:48 -0400
To: "'Jasper van de Gronde'" <th.v.d.gronde@hccnet.nl>, <www-svg@w3.org>
Message-ID: <000001cc8289$34a48770$9ded9650$@net>
Thanks for following up here. Wrapping patterns as in the wallpaper groups,
is indeed sort of what I have in mind. 

Consider the examples at 

http://granite.sru.edu/~ddailey/svg/pattern6.svg
and
http://granite.sru.edu/~ddailey/svg/pattern7.svg 
 (or the animated one at
http://granite.sru.edu/~ddailey/svg/pattern2.svg 
)

Note how in pattern6, we may draw lines at the edge of the pattern space
that avoid contact with any of the ovals. If we wish to "pack" the space
more densely by interrupting those lines, by moving one of the ellipses
closer to the edge as in Pattern7, note that the oval is truncated by the
pattern space rather than bulging out on the other side. That's what I mean
by "toroidal wrapping".

To accomplish this wrapping effect, as seen at 

http://granite.sru.edu/~ddailey/svg/pattern5.svg 

The brown oval had to be drawn four times (at each corner of the pattern
space). It is not hideously complicated for an author to do this in such a
simple example, but as the complexity of the pattern content grows, the
nuisance is exaggerated.

Some of my other experiments with tiling can be seen at
http://srufaculty.sru.edu/david.dailey/svg/SVGOpen2008/edges_of_plausibility
.htm under "non-rectangular tilings"

I'm simply suggesting that a <pattern type="wrap" > attribute that allows
content on the edges to wrap to the other side of the torus would be a
convenience for authors and relatively easy to implement.

Cheers
David

-----Original Message-----
From: www-svg-request@w3.org [mailto:www-svg-request@w3.org] On Behalf Of
Jasper van de Gronde
Sent: Tuesday, October 04, 2011 3:41 AM
To: www-svg@w3.org
Subject: Re: patternTransform -- and toroidal wraps

On 04-10-11 03:35, David Dailey wrote:
> ...
> While on the topic of patterns and transforms, a thing has troubled me for
some time about patterns:
> 
> Wouldn't it be nice to have the ability to allow a shape within the
pattern space to "wrap"?
> 
> That is, instead of having sharp edges, suppose we had the option of
making pattern tiles toroidal.
> Like in the game of Asteroids, the top of the rectangle and the bottom are
identified (wrapped), as are the left and right edges, so that the user can
specify that any content on the edge wraps around. This allows for the
creation of seamless tilings that are the mainstay of wallpaper,
counter-tops, carpet, etc. I have some examples laying about here or there
if my meaning isn't apparent. At least four centuries of "ornamental design"
are submitted as use cases. If type="wrap" is in the spec, I haven't seen
it.

I'm not entirely sure what you mean, patterns are tiled, which
effectively identifies the left and right, as well as the top and bottom
edges. Or do you want to be able to do something like this and have it
look like a series of parallel, unbroken, lines (as opposed to a series
of line segments laid out in a grid pattern):

<pattern width="1" height="1">
  <path d="M 0,0 L 0.8,0.8 z" />
</pattern>

(The rationale is that if you have a truely toroidal space, the shortest
path from 0.8,0.8 to 0,0 is through 0.9,0.9.)

Actually, it might make more sense to immediately go to the famed
"wallpaper groups". Googling should get you some examples, and if you
want to experiment with these, Inkscape can create tiled clones in
patterns corresponding to these groups. (And again, virtually all have
been used in the past in actual wallpapers or other decorations.)
Received on Tuesday, 4 October 2011 11:32:15 GMT

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