[x3d-public] unmatched xxxTextureMapping

[Brutzman, Donald (Don) (CIV)]

Thanks for noticing this.

Yes, X3D does not get directive about how to handle problem cases because that can lead to unintended requirements or inefficient performance reactions trying to handle a trouble case in content.  Thus browsers have latitude in how to respond (or ignore).

Prose inputs welcome for an specification addition, e.g. perhaps something like

  *
"Rendering response is undefined when provided texture coordinates do not correspond to other defined texture-mapping parameters."


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 https://faculty.nps.edu/brutzman
________________________________
From: x3d-public <x3d-public-bounces at web3d.org> on behalf of Andreas Plesch via x3d-public <x3d-public at web3d.org>
Sent: Friday, February 21, 2025 10:31 AM
To: X3D Graphics public mailing list <x3d-public at web3d.org>
Cc: Andreas Plesch <andreasplesch at gmail.com>
Subject: [x3d-public] unmatched xxxTextureMapping

As https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD/Part01/components/shape.html#TextureMappingCoordinate

and co. explains the xxxTextureMapping field can be used to have multiple sets/channels of TextureCoordinates for the same Shape, for different types of Textures.

There is one case which is not covered, presumably because it typically would indicate a mistake or oversight by the author. What should a browser implementation do if a material has a (non-default) xxxTextureMapping which does not match any of the provided TextureCoordinates for the Shape ?

Possibilities are fall-back to default texture coordinates, fall-back to the first provided mapping, fall-back to constant uv 0,0 to indicate visually a problem, or undefined behaviour.

Undefined behaviour might be ok but it is then worth pointing out in the spec.

Thanks, -Andreas

--
Andreas Plesch
Waltham, MA 02453
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