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Re: [Public WebGL] Re: WebGL spec modifications for D3D



On Sat, Jun 26, 2010 at 5:17 PM, Steve Baker <steve@sjbaker.org> wrote:
> YIKES!!!
>
> Lack of shader invarience can be a major headache in many common
> multipass algorithms.  Without the 'invariant' keyword, we're going to
> need something like the 'ftransform' function (which I think was
> obsoleted in GLSL 1.4 and GLES 1.0).
>
> Without EITHER 'invariant' OR 'ftransform', some rather important
> algorithms become impossible - and that would be really bad news!

Sorry for the long delay in replying.

The removal of the invariant enforcement was recommended by
TransGaming based on its not being implementable on D3D9. Perhaps
someone from TG could comment more on the exact issue and what is
possible to implement. I agree that its removal seems to preclude
multi-pass rendering algorithms in WebGL 1.0.

-Ken

>  -- Steve
>
>>> On Thu, Apr 22, 2010 at 12:18 PM, Vangelis Kokkevis <vangelis@google.com>
>>> wrote:
>>>
>>>> 5. Shader invariance as described in GLSL ES spec
>>>> (http://www.khronos.org/registry/gles/specs/2.0/GLSL_ES_Specification_1.0.17.pdf)
>>>> sections 4.6.1 and enforced by the "invariant" qualifier and #pragma STDGL
>>>> invariant(all) cannot be guaranteed in D3D9.  Spec change: No guarantees are
>>>> made about invariance in shader outputs the invariant qualifier and #pragma
>>>> are ignored.
>>>>
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