[x3d-public] alphaChannel accessType inputOutput?

[Michalis Kamburelis]

Yes, I believe this can be "[in,out]".

Changing this at runtime is certainly possible. Albeit it changes the
order of rendering (blending vs non-blending) and requires shader
change (for alpha test). But that's not critical.

Regards,
Michalis

śr., 27 sty 2021 o 18:50 Don Brutzman <brutzman at nps.edu> napisał(a):
>
> Proposed alphaChannel field signature follow.
>
> Appearance {
>    ... all normal Appearance fields ...
>    SFString   []            alphaChannel  "AUTO"      # "AUTO", "NONE", "TEST" or "BLENDING"
> }
>
> The syntax "[]" indicates accessType initializeOnly.
>
> Michalis, is it possible to have "[in out]" accessType inputOutput?  This wont' be a commonly used feature, and might not be super performant, but there is a use case.  Modifying this value can let authors compare techniques and might also provide end users with a visualization technique (discerning subtle texture features as they are applied to geometry).
>
> Thanks for considering this possibility.
>
>
> On 1/24/2021 10:33 AM, Don Brutzman wrote:
> > 2. Khronos feedback comments: path forward
> >
> > a. Immediate response to change X3D4 specification
> >
> > Helpful deficiency feedback during ballot period regarding alphaChannel for Appearance.
> >
> > [2.1]    Specify alpha channel treatment (field alphaChannel for Appearance)
> > https://castle-engine.io/x3d_implementation_shape_extensions.php#section_ext_alpha_channel
> >
> > Please see email report by Don McCurdy and response by Michalis Kamburelis.
> >
> > [2.2]    [x3d-public] [x3d] Spec Comment by on 19775-1: X3D Architecture - V4.0; add Appearance alpha channel for consistency with glTF
> > https://web3d.org/pipermail/x3d-public_web3d.org/2021-January/014569.html
> >
> > Initial placeholder has been added to github specification and Michalis will continue with prose next week.  If one more week is needed to finish, we will allow that.
> >
> > Needed clarification: default value "AUTO" means that other requirements in the specification are handled without change.
> >
> > This is implemented (or nearly done) in Castle Game Engine.  How about assessment by other browsers: X_ITE, X3DOM, FreeWrl?
> >
> > Tracking as
> >
> > [2.3]    Mantis 1340, add Appearance alpha channel for consistency with glTF
> > https://www.web3d.org/member-only/mantis/view.php?id=1340
>
> all the best, Don
> --
> Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
> Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
> X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman
>
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