[x3d-public] coord = NULL ?

[Brutzman, Donald (Don) (CIV)]

Good question, thanks Andreas.

In general the architecture specification tries to remain silent about reporting errors and warnings.  We're not opposed to them!  However detection and handling of such conditions can reduce performance and sometimes be problematic to comply with, so we avoid that.

Your comments seem sensible to me.  I'd certainly not expect to see any geometric rendering of a Shape if no coordinates were provided by the author.  I will check X3D Schematron to confirm whether we have warnings about that model condition.  Perhaps it should be noted in X3D Tooltips and X3D Scene Authoring Hints as well.

BTW recommend using version "CD1" to see continuing editorial corrections by Dick Puk and I following recent CD ballot submission to ISO.

* https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD1/Part01/components/rendering.html#X3DComposedGeometryNode

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

-----Original Message-----
From: x3d-public <x3d-public-bounces at web3d.org> On Behalf Of Andreas Plesch
Sent: Sunday, November 7, 2021 7:59 PM
To: X3D Graphics public mailing list <x3d-public at web3d.org>
Subject: [x3d-public] coord = NULL ?

X3DComposedGeometry based nodes have a coord field which is NULL by default:

https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-CD/Part01/components/rendering.html#X3DComposedGeometryNode

But the spec. language does not spell out what a browser should do with a NULL value for the coord field, in contrast to other fields like color or normal.

It may seem nonsensical to have a geometry node with null coordinates and therefore deemed outside the scope of the spec. But as it is an in,out field, coord may be updated, and an initial NULL may have then use cases. So a NULL value should at least generate no fatal error, and probably no warning. Are there other aspects to consider ? Should there be a difference between a NULL coord field, and a default Coordinate node with an empty array for its point field ? It seems not.

It seems self-evident that there should not be any rendering activity, and that routing through other fields should still occur while coord is NULL.

It may be fine to leave behaviour to browsers with the expectation to do something sensible.

Andreas
--
Andreas Plesch
Waltham, MA 02453

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