[x3d-public] [x3dom-users] bboxDisplay considerations; metadata nodes for new field extensions

John Carlson yottzumm at gmail.com
Sat Apr 1 14:07:53 PDT 2023

Re: Subdivision metadata in addition to bboxDisplay

Don, all,

I agree on metadata extension handling for bbox.  Perhaps our second step
might be adding “subdivision/subdivisions” metadata extensions to Sphere,
and later, once the idea is proven, to other shapes.   This subject has
already been discussed and rejected as an attribute, ad naseum, so indeed,
this would remain metadata indefinitely.   This new approach has the
advantage of making “subdivision” validation possible, and let browsers
adopt it as desired.

The problem is “subdivision(s)” is already an attribute in X3DOM.  There
are also different global quality parameters, especially in X_ITE.  Having
a unified, XML-based approach would be terrific.

Another alternative is using NURBS/IFS.  These may have issues with seams
and performance.  Positions would be offset radially.  Ideally, we’d doing
position offsets in shaders, if nowhere else.   We could use sphere meshes
in X3D code, that is very doable, but bloat.   Possibly use glb?

Note that I’ve successfully generated a sphere mesh in Blender an imported
the mesh into a PlayCanvas and applied shaders, so I’m fully cognizant that
this is doable on the web:
https://playcanv.as/p/wQgQBgkE/. I have not achieved similar quality with
X3D (challenge?)

Note that the sphere mesh will be animated, and perhaps we can created
standardized animations, like squash and stretch?


On Sat, Apr 1, 2023 at 2:58 PM Brutzman, Donald (Don) (CIV) <
brutzman at nps.edu> wrote:

> Thanks for continuing news about this excellent progress.
> Am thinking we might all agree to regularize addition of nonstandard
> fields in a way that still passes content validation.
> For example, non-standard experimental example
> <Shape bboxDisplay='true' bboxColor='0.7 0.8 0.9' bboxMargin='0.1' >
>    <Sphere/>
> </Shape>
> Might be equivalently and validly expressed as
> <Shape bboxDisplay='true'>
>    <MetadataSet name='extension'>
>         <MetadataString name='bboxColor' value='0.7 0.8 0.9'/>
>         <MetadataString name='bboxMargin' value='0.1' />
>    </MetadataSet>
>    <Sphere/>
> </Shape>
> A little more verbose perhaps... However, note that not only is model
> content validatable, but metadata content might also be validated if we
> build a metadata vocabulary that lists experimental field names, types and
> default values.  That way common extensions might be more sharable and
> model content remains confirmably correct.
> Seems like a useful good practice that isn't complex, so we could easily
> build <MetadataSet name='extension'> capabilities into our browser parsers
> and authoring tools.
> The X in X3D is Extensible... looking forward to continued innovation and
> practice/progress together.
> v/r Don
> -----Original Message-----
> From: Andreas Plesch <andreasplesch at gmail.com>
> Sent: Saturday, April 1, 2023 6:43 AM
> To: X3D <x3d-public at web3d.org>
> Cc: x3dom mlist <x3dom-users at lists.sourceforge.net>
> Subject: Re: [x3dom-users] [x3d-public] bboxDisplay considerations
> The bboxDisplay field is now available for bounded objects (grouping nodes
> and shapes) in the dev. version of x3dom.
> The color of the displayed bounding box can be customized with the
> non-standard bboxColor field, and the size expanded with the bboxMargin
> field.
> Enjoy ! Andreas
> On Thu, Mar 30, 2023 at 2:19 PM Andreas Plesch <andreasplesch at gmail.com>
> wrote:
> >
> > I think it will be very useful to allow different colors for different
> > sets of bounding boxes. Here are the rotating cubes with two sets of
> > bounding boxes. The yellow ones react to a TouchSensor, the orange
> > ones do not:
> > [...]
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