Re: filter primitive subregion and feGaussianBlur

On Sat, Jan 29, 2011 at 4:03 AM, Erik Dahlstrom <ed@opera.com> wrote:

> This is a response to
> http://lists.w3.org/Archives/Public/www-svg/2008May/0013.html (tracked as
> ISSUE-2334).
>
>  "Restricts calculation" is a bit ambiguous. Does this mean:
>> -- The implementation takes a snapshot of the input image, with the
>> geometry
>> of the snapshot determined by the filter primitive subregion for the
>> feGaussianBlur, and performs processing on that, treating the boundaries
>> of
>> the snapshot as the boundary where boundary conditions are applied.
>> or something else?
>>
>
> The spec has been updated [1] as agreed in [2] to say that:
>
> [[
>  ‘x’, ‘y’, ‘width’ and ‘height’ act as a hard clip clipping rectangle on
> both the filter primitive's input image(s) and the filter primitive result.
> ]]
>

That sounds fine.


>
>  BTW the spec also says
>>
>>> If the input has infinite extent and is a tile, the filter is evaluated
>>>
>> with periodic boundary conditions.
>>
>> I'm not sure what it means for the input to have infinite extent in this
>> context, and I'm not sure what it means to be "a tile". Does it mean that
>> the input is an feTile? Could this be more precisely defined?
>>
>
> Updated [3][4] to say:
>
> [[
> If the input has infinite extent and is constant (e.g FillPaint where the
> fill is a solid color), this operation has no effect. If the input has
> infinite extent and the filter result is the input to an ‘feTile’, the
> filter is evaluated with periodic boundary conditions.
> ]]
>

What does "periodic boundary conditions" mean?

Rob
-- 
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