RE: [filter-effects] @support condition for custom filters

[Dirk Schulze:]
> 
> 
> On Feb 11, 2013, at 5:55 PM, James Robinson <jamesr@google.com> wrote:
> 
> >
> >
> > On Mon, Feb 11, 2013 at 3:05 PM, Dirk Schulze <dschulze@adobe.com>
> wrote:
> > Hi all,
> >
> > The Filter Effects[1] specification defines the custom() filter function
> to extend the predefined filters by new, customized filters including CSS
> Shaders, but not limited to CSS Shaders. This was discussed and accepted
> by the SVG WG [2].
> >
> > Feature detection is important to support future extensions of the spec
> and test for the availability. I have an action from the SVG WG to ask for
> a new condition 'filter' on the @support rule. This filter descriptor can
> take different feature keywords. For CSS Shaders I would suggest 'webgl'
> because of the relation to WebGL. More feature keywords can be added by
> future versions of Filter Effects allowing other or future shading
> languages and parameterized SVG filters. The filter condition would look
> like in the following demonstration:
> >
> > Supporting webgl and supporting CSS shaders are very different things
> and I would not expect support for one to imply or match support of the
> other.  I think you should pick a different keyword.
> 
> I am happy with a different keyword as well. This name was proposed during
> the F2F, since CSS Shaders use the by WebGL defined shader language (GLSL
> ES with restrictions). In theory you can use a different shading language
> to archive the same results. I am open for other name proposals.
> 

Aren't you really trying to check for support for a function e.g. something
like @supports (filter:custom()) ?