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Re: [filters] Shading language recommendation

From: David Sheets <kosmo.zb@gmail.com>
Date: Wed, 22 Aug 2012 19:22:57 -0700
Message-ID: <CAAWM5TzN=56X7isq0HimWGmM3guiRdYz6aRc=SORCd_M1hinsA@mail.gmail.com>
To: Sylvain Galineau <sylvaing@microsoft.com>
Cc: "public-fx@w3.org" <public-fx@w3.org>
On Tue, Aug 21, 2012 at 9:52 AM, Sylvain Galineau
<sylvaing@microsoft.com> wrote:
> The normative prose of section 38.2 'Recommended shading language' recommends
> GL SL ES [1]. Per RFC2119 this means implementers MUST support GL SL ES
> unless there exist 'valid reasons in particular circumstances' to ignore this
> recommendation.
>
> While Microsoft has no objection to defining how the feature works for UAs
> that choose GL SL ES as defined by Web GL 1.0, we object to its normative
> recommendation. This was the reason for the note in the same section, note
> which looks at best confusing if not contradictory given the normative
> recommendation that precedes it.
>
> We would prefer to follow a pattern similar to the informative section 6.1 in
> Media Source Extension[2]: "This section defines segment formats for
> implementations that choose to support WebM". We think the ability to specify
> multiple shading languages is important, as broadly suggested by the current
> note. This allows sites to work with different user agents supporting different
> shading languages. For example, a future version of GL SL ES with fallback to
> the current version for user agents that don't yet support the new version.

As I pointed out elsewhere in this thread, GLSL ES supports a
forward-compatible internal version declaration. GLSL ES presently
lacks a standard external media type representation contravening World
Wide Web convention. Registration of a media type was proposed months
ago on the public WebGL mailing list but received no official
response.

As I understand it, your present proposal is to use a binary header
format for shader type declaration. Why?

Specifically, what is your objection to using internet standard media
types for this shader type declaration as described in the FX draft
you referenced?
<https://dvcs.w3.org/hg/FXTF/raw-file/tip/filters/index.html#recommendation>

Why would you like to include the language metadata inside the resource itself?

Thank you,

David Sheets

> [1] https://dvcs.w3.org/hg/FXTF/raw-file/tip/filters/index.html#recommendation
> [2] http://dvcs.w3.org/hg/html-media/raw-file/tip/media-source/media-source.html
>
>
>
Received on Thursday, 23 August 2012 02:24:12 GMT

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