Re: feTurbulence with filter primitive subregions

On Mon, May 12, 2008 at 5:31 AM, Erik Dahlström <ed@opera.com> wrote:

> On Sun, 11 May 2008 09:24:01 +0200, Robert O'Callahan <
> robert@ocallahan.org> wrote:
>
>  It's not clear to me from the spec what the 'point' parameter of the
> > 'turbulence' function means.
> >
> > Suppose I have
> > <filter primitiveUnits="userSpaceOnUse" x="0" y="0" width="20"
> > height="20">
> >  <feTurbulence x="10" y="10" width="10" height="10"/>
> > </filter>
> >
> > When we compute 'turbulence' for the top-left corner of the feTurbulence
> > filter primitive subregion, what is 'point'? I assume it's either (0,0)
> > or (0.5,0,5).
> >
>
> I think that should depend on how an implemention does sampling in
> general. It's unlikely that an error would be easy to spot in most cases
> though.
>

'point' values range from 0 to 1, don't they? So you'd get a completely
different image depending on whether you interpret the turbulence as filling
the filter region and being clipped to the filter primitive subregion, or
just filling the filter primitive subregion.

Rob
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