[x3d-public] alphaChannel accessType inputOutput?

[Don Brutzman]

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