[x3d-public] Simplifying ProtoInstance nodes

Sat May 10 11:38:24 PDT 2025

I think this short form (in XML encoding) makes sense, and Castle Game
Engine / Castle Model Viewer could support it too.

It makes XML encoding and classic encoding more consistent: you can use
PROTO to define a new node, and then use the new node with the same syntax
as "built-in nodes". This is already true for classic encoding, it's nice
to bring this feature to XML encoding.

Don has already expressed the important drawback of this "short form": such
XML will not validate. I mean, it will validate in X3D-specific tools like
"castle-model-converter --validate .." (once we add support for it), but
the general XML validation using XML Schema has no way of validating it.
You cannot tell in XML schema "this XML element name is valid, if defined
by some XML attribute elsewhere". I'm guessing this was the whole reason
why ProtoInstance, fieldValue etc. were invented in XML encoding.

I'm guessing in JSON X3D encoding, the consideration will be similar: it
can be implemented, but the resulting file will not validate with JSON
schema ( https://json-schema.org/ ).

Anyhow, if we're all fine with accepting this drawback, then we sure can go
ahead and add it to spec :) As long as "long form" remains available, and
thus tools like XML schema and JSON schema remain useful, I think it makes
sense to have this choice.

Regards,
Michalis

sob., 10 maj 2025 o 18:38 Brutzman, Donald (Don) (CIV) via x3d-public <
x3d-public at web3d.org> napisał(a):

> Thanks for the interesting, innovative discussion.  Excerpting the example:
>
>
>    -
>    https://create3000.github.io/x_ite/tutorials/creating-new-node-types/#using-prototyped-nodes
>
>
> _________________________
> XML Encoding
>
> 1
> 2
> 3
> 4
> 5
> 6
> 7
> 8
> 9
>
> <!--* Official Syntax *-->
> <ProtoInstance name='BouncingBall'>
>   <fieldValue name='cycleInterval' value='2'/>
>   <fieldValue name='bounceHeight' value='3'/>
> </ProtoInstance>
> <!-- *Short Syntax *-->
> <BouncingBall
>     cycleInterval='2'
>     bounceHeight='3'/>
>
> Classic VRML Encoding
>
> 1
> 2
> 3
> 4
>
> BouncingBall {
>   cycleInterval 2.0
>   bounceHeight  3.0
> }
>
> _________________________
>
> One drawback with the "short" XML syntax is that it will not pass XML
> DOCTYPE or XML Schema validation, although it still must conform to XML
> well-formed rules.  Additional tool-specific capabilities can check for
> such correctness during parsing, of course.  Avoiding XML validation
> relaxes quality assurance (QA)  for the entire scene, not just that
> prototype instance, and so use of the short form should be considered
> carefully.
>
> Of course there is much merit too, not least of which are readability and
> consistency with other XML-encoded nodes.
>
> As it turns out, now is a good time to consider such a change to the X3D
> Standards suite.  We have highly mature documents defining X3D encodings
> using XML and ClassicVRML syntax.  Conceivably a "short" form for
> ProtoInstance will carry over satisfactorily for JSON and other encodings
> as well, when we get to them this fall.
>
> If X_ITE and X3DOM already handle this form, and if Castle Model Viewer
> (Castle Game Engine) is also supportive, I'm not yet seeing any blockers to
> adoption.  Further implementation and evaluation of course will be useful
>
> Reference and specific clause that would need modification:
>
>
>    - *X3D XML Encoding 4.0
>    <https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19776-1v4.0-WD1/Part01/X3D_XML.html>*
>     revision 19776-1
>    - 4.3.3.2  ProtoInstance node and fieldValue statement syntax
>    -
>    https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19776-1v4.0-WD1/Part01/concepts.html#ProtoInstanceAndFieldValueStatement
>
>
> Probably no changes needed:
>
>
>    - *X3D Classic VRML Encoding 4.0
>    <https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19776-2v4.0-WD1/Part02/X3D_ClassicVRML.html>*
>     revision 19776-2
>    - 4.3.3.2 Prototype instances and field value initialization syntax
>    -
>    https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19776-2v4.0-WD1/Part02/concepts.html#ProtoInstanceAndFieldValueStatement
>
>    - *X3D Architecture 4.1
>    <https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/Architecture.html>*,
>    revision 19775-1
>    - 4.4.4 Prototype semantics
>    -
>    https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/concepts.html#PrototypeSemantics
>
>
> Thanks for careful consideration of this potential capability.  All
> feedback welcome.
>
> Have fun with X3D extensibility!  🙂
>
> 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 on behalf of Holger Seelig via x3d-public
> *Sent:* Saturday, May 10, 2025 1:13 AM
> *To:* X3D
> *Cc:* Holger Seelig
> *Subject:* Re: [x3d-public] Simplifying ProtoInstance nodes
>
> This is already possible if you use the „short syntax“ of a proto instance:
>
>
> https://create3000.github.io/x_ite/tutorials/creating-new-node-types/#using-prototyped-nodes
>
> You can use this in X_ITE, but also in X3DOM.
>
> Best regards,
> Holger
>
> --
> Holger Seelig
> Leipzig, Germany
>
> holger.seelig at yahoo.de
> https://create3000.github.io/x_ite/
> https://patreon.com/X_ITE
>
>
>
> Am 10.05.2025 um 05:55 schrieb John Carlson via x3d-public <
> x3d-public at web3d.org>:
>
> My thought is to replace “ProtoInstance” tags with “MenuItem” tags, and
> fieldValue statements with attributes, but I’ve not done that before. My
> goal is to make the model more accessible to screen readers.
>
> Any examples are welcome.
>
> See attached link and model.
>
> John
>
> ---------- Forwarded message ---------
> From: *John Carlson* <yottzumm at gmail.com>
> Date: Thu, Mar 6, 2025 at 4:35 PM
> Subject: Latest cleaned Jin FACS (needs metadata)
> To: Don Brutzman <brutzman at nps.edu>, Joe D Williams <joedwil at earthlink.net
> >
>
>
> Attached.
>
> And:
>
> https://create3000.github.io/x_ite/playground/?url=https://raw.githubusercontent.com/coderextreme/ci2had/refs/heads/main/resources/CleanedYouClocks.x3d
>
> John
> <CleanedYouClocks.x3d>_______________________________________________
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