[x3d-public] [x3d] Spec Comment by walroy on 19775-1: Abstract X3D Definitions - V3.3 [Mantis 1171]

[Roy Walmsley]

Hi,

I have raised a Mantis issue to cover the specification comment appended
below. It is Mantis issue 1171. The issue is available to Web3D members at
http://www.web3d.org/member-only/mantis/view.php?id=1171.

I raised this comment as a follow up to the discussion on the public mailing
list under the title "STL File Format for 3D Printing - Simply Explained |
All 3DP". The first message in this thread is available at
http://web3d.org/pipermail/x3d-public_web3d.org/2017-August/007325.html.

All the best,

Roy

-----Original Message-----
From: x3d [mailto:x3d-bounces at web3d.org] On Behalf Of Spec Feedback
Sent: 14 August 2017 14:45
To: x3d at web3d.org
Subject: [x3d] Spec Comment by walroy on 19775-1: Abstract X3D Definitions -
V3.3

-- Submitter indicates that this comment may be public: *Yes* --

Comment on 19775-1: Abstract X3D Definitions - V3.3
9.3.2 X3DUrlObject
http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/networking.html#X3DUrlObject

-----------------
Subject: Incorrectly restricts to valid X3D files.

The text in the third paragraph reads as follows:

"Each specified URL shall refer to a valid X3D file that contains a list of
children nodes, prototypes and routes at the top level as described in
10.2.1 Grouping and children node types. The results are undefined if the
URL refers to a file that is not an X3D file, or if the X3D file contains an
invalid scene."

This interface is inherited by a number of nodes, as listed below:

Script, via X3DScriptNode
Anchor
AudioClip
DISEntityTypeMapping
GeoMetadata
ImageCubeMapTexture
ImageTexture
ImageTexture3D
Inline
MovieTexture
PackagedShader
ShaderPart
ShaderProgram

Most of these use the 'url' field to point to file types other than X3D. For
example, the ImageTexture node (see 18.4.1 ImageTexture) is required to
support JPEG and PNG file formats as a minimum.

However, even when the 'url' field is used for X3D files (e.g. Inline,
Anchor) the question arises whether importing other file types should be
permitted (e.g. STL, 3DS), provided they are internally converted, on
loading, into X3D scene graph structures.

I propose that this clause should be rewritten to generalize the 'url'
field.
The text on X3D file loading would then be a subset of the possible file
types, which might also cover importing other 3D file types, such as STL,
for example.

There has, of course, also been discussion of potential "ExternalGeometry"
and "ExternalShape" nodes for V4 of X3D. How might these compare to the
importing of different file types using the 'url' field of nodes inheriting
the X3DUrlObject interface. For instance, how would "ExternalShape" or
"ExternalGeometry" differ from Inline?
-----------------

Submitted on Monday, 2017,  August 14 - 2:44pm by walroy (walroy )
IP: 82.31.58.84

See: http://www.web3d.org/node/1694/submission/1424


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