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Re: Pan Wrap

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Tue, 17 Jul 2012 09:57:27 -0700
Message-ID: <CAAWBYDCYK0TbWkQ=gVXUv_8A=cAJRqDqLSDy7cfhUcEj7kCdqw@mail.gmail.com>
To: Jasper van de Gronde <th.v.d.gronde@hccnet.nl>
Cc: www-svg@w3.org
On Mon, Jul 16, 2012 at 8:30 AM, Jasper van de Gronde
<th.v.d.gronde@hccnet.nl> wrote:
> On 16-07-12 16:56, Doug Schepers wrote:
>>
>> Hi, folks-
>>
>> I was just reminded of a use case I thought of long ago, but never
>> articulated: the ability to wrap an SVG image on either (or both) the x
>> or y axis.
>
>
> This is effectively an example of wanting to construct a pattern with one of
> the wallpaper symmetry groups. These are extremely well researched, so when
> considering extending SVG with this kind of concept it could be very helpful
> to take a closer look at these:
>
> http://en.wikipedia.org/wiki/Wallpaper_group#The_seventeen_groups
>
> In particular, what you're suggesting is effectively group p1 (with some
> constraints on the possible translations), and with a little effort you
> could easily imagine adding support for at least some of the more closely
> related groups, like p2, pm, pg, pmm, pmg and pgg. All of these groups have
> real-world examples, although perhaps more for creating patterns than tiling
> the viewbox (although in a sense the whole SVG image is then treated as a
> pattern).
>
> To continue your map use case, instead of just allowing horizontal wrapping,
> it might make sense to also allow vertical wrapping (for certain projections
> this makes perfect sense, look for the Peirce quincuncial projection for
> example). Now a simple "wrapping" isn't enough, you need something more,
> like p2 (which contains 180 degree rotations), or pm (which contains
> reflections).

I like the idea of somehow exposing the wallpaper groups.  The trick
is to do so in a way that's usable to normal people.  ^_^  Even if we
only expose a subset, though, this is really useful to understand what
we might want to do.

~TJ
Received on Tuesday, 17 July 2012 16:58:15 GMT

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