[x3d-public] X3D Working Group meeting 23 SEP 2022: Mantis issues review SvgTexture, X3D Application Stack

Sat Sep 24 11:00:36 PDT 2022

Hi Doug.  Regarding WebAssembly, I think it fits as one of many many
technologies available to Web authors, represented in the X3D Application
Stack - Layers and Alternatives diagram in the row Programming Libraries,
Web authoring tools and 3D translators.

*	https://webassembly.org

Hi John.  glTF is a format for 3D models, and that is why you find multiple
ways to use glTF2 as a 3D model in the X3D Specification.  glTF itself is
not suitable as any kind of format to provide an image texture.

1.	First: glTF models can be loaded via Inline

*	X3D Part 1: Architecture and base components, 9 Networking
component, 9.4.2 Inline
*
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-DIS/Part01/
components/networking.html#Inline

The run-time system can support any number of 3D model resource types as
long as those follow the abstract model definition (see 2.[RFC2077]),
provide a registered content type ( e.g., model/x3d-xml, model/gltf-bin,
model/stl, etc.), and can be determined with some form of content
negotiation (see 2.[RFC2616]). The run-time system must support at least one
X3D type ( e.g., model/x3d-xml) but can also support and negotiate any
number of X3D encodings and (optionally) non-X3D representation formats.
Support for loading glTF assets (see 2.[GLTF]) also requires support for
Shape component level 2 and Lighting component level 4.

*	Table 9.3 - Networking component support levels
*
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-DIS/Part01/
components/networking.html#t-supportLevels
*	Level 5, Model support

Support for glTF models in Inline nodes, in .gltf (model/gltf+json) and .glb
(model/gltf-binary) formats.

Requires support for Shape component level 2 and Lighting component level 3.

Minimum required glTF support:

*	transformation hierarchy,
*	meshes,
*	physical materials,
*	loading of external binary data referenced from .gltf files ( e.g.,
for vertex coordinates).

2.	Second: glTF2 rendering techniques are fully integrated into native
X3D4 lighting and rendering models, thus encouraging compatible modeling and
conversion of glTF models in X3D.

*	X3D Part 1: Architecture and base components, 12 Shape component,
12.4.6 PhysicalMaterial
*
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-DIS/Part01/
components/shape.html#PhysicalMaterial

The PhysicalMaterial node specifies surface material properties for
associated geometry nodes. It indicates that a physical lighting model
should be used for the computation. 17 Lighting component contains a
detailed description of the X3D lighting model equations.

Physical interpretation of the material parameters follows. These parameter
descriptions closely follow the glTF specification (see [glTF]).

NOTE   The physical material properties of X3D are also deliberately
consistent with the glTF 2.0 material definition. Effectively, converting
(in either direction) between X3D PhysicalMaterial and glTF 2.0 material
definitions is equivalent.

*	also 12.4.10 UnlitMaterial
*
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4-DIS/Part01/
components/shape.html#UnlitMaterial

Also please be aware that we are not pursuing a specific design for
SvgTexture or related new-node possibilities at this time.  Rather we are
performing our "final final" review of X3D4 issues in Mantis.  Thaat issue
asks whether SVG ought to be included among allowed url file types for
ImageTexture.   Currently the rationale appears to be no, continuing comment
welcome.  The X3D Working Group will finalize resolution of Web3D Consortium
comments on X3D4 Draft International Standard Ballot on Friday October 7.

*	Mantis 1400: add Scalable Vector Graphics (SVG) to recommended image
formats for ImageTexture
*	https://www.web3d.org/member-only/mantis/view.php?id=1400

More documentation about glTF and X3D correspondences is found in recent
spreadsheet-comparison efforts by X3D Working Group.  I have moved both of
these documents from other locations into our central Web3D sourceforge
repository.

*	X3D Application Stack - Layers and Alternatives
*
https://www.web3d.org/specifications/X3dApplicationStackLayersAlternatives.p
ng

*	Features Comparison X3D4 glTF2 spreadsheet
*	https://www.web3d.org/specifications/FeaturesComparisonX3D4glTF2.pdf

and now highlighted at

*	X3D Specifications: Schema and DOCTYPE Validation
*	https://www.web3d.org/specifications

Ongoing scrutiny and insights are always welcome.  Have fun building X3D
Applications!  8)

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: John Carlson <yottzumm at gmail.com> 
Sent: Saturday, September 24, 2022 8:41 AM
To: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu>
Subject: Re: [x3d-public] X3D Working Group meeting 23 SEP 2022: Mantis
issues review, SvgTexture

Perhaps we should generalize to GraphicsTexture and include glTF in the FULL
profile, and SVG in a simpler profile.

At this point, it seems like Inline would be a required child of
GraphicsTexture, with animation, encoding and navigation options.

I realize I should be checking the ticket and standard.

Yes, I recognize "portals" from Squeak here.  Seeing into another scene.   I
think Anchors are okay here.   There's no HTML5 within HTML5, so there's no
precedent.

John

On Sat, Sep 24, 2022 at 9:55 AM Brutzman, Donald (Don) (CIV)
<brutzman at nps.edu <mailto:brutzman at nps.edu> > wrote:

John, there is a bit more in the issue and the references.

SVG produces animatable interactive 2D images through vector graphics.  So
it has characteristics of both ImageTexture and MovieTexture (and
interpolators and scriptable event models).

Dick's point yesterday was that implementing such a combination is different
and bigger than ImageTexture or MovieTexture.  The ways that an author might
use an SVG model are similar, but when you think of how a browser might do
it and then add computation, user interaction, security, etc. etc. then the
design perspective is quite different.  This leads us to the tried-and-true
approach of implementing and testing further, most likely as a new node.

So I think that is an interesting and important justification that he made.
We offer it back to the group for review and discussion - thanks for your
points.

all the best, Don

-- 

Don Brutzman  Naval Postgraduate School, Code USW/Br        brutzman at nps.edu
<mailto: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 <http://faculty.nps.edu/brutzman> 

From: John Carlson <yottzumm at gmail.com <mailto:yottzumm at gmail.com> > 
Sent: Friday, September 23, 2022 5:33 PM
To: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu <mailto:brutzman at nps.edu>
>
Cc: X3D Public Mailing List (x3d-public at web3d.org
<mailto:x3d-public at web3d.org> ) <x3d-public at web3d.org
<mailto:x3d-public at web3d.org> >
Subject: Re: [x3d-public] X3D Working Group meeting 23 SEP 2022: Mantis
issues review, ballot deadlines, X3D Application Stack Layer Examples
diagram

Recommendation:  SvgTexture should be a single frame MovieTexture for now,
with possible extensions to animation with ROUTEs and ECMAscript, if
animation is enabled on SvgTexture node.  I don't know if MovieTexture
enables/disables animation, but my guess is, yes.

Disabling/enabling animation of SVGs should be in more inclusive profiles.

Is that simple enough?

On Fri, Sep 23, 2022 at 7:23 PM John Carlson <yottzumm at gmail.com
<mailto:yottzumm at gmail.com> > wrote:

Consider:   SVG is a manipulation language for inserting 2D graphics into a
scene.   Definition languages are more closely related to schemas, or
possibly for manipulating schema.  After insertion into a scene, ECMAscript
is typically used for manipulation.   ROUTEs should be allowed to as well.

SVGs should be considered animations with popular packages being D3.js.

Otherwise,  SVG is a declarative language, similar to X3D and HTML.   Last I
heard, there was no official schema for SVG.

If the SVG is animated by ECMAscript, wouldn't it more properly be used to
texture surfaces and volumes with a MovieTexture?  Are MovieTextures 2D or
3D?   What textures are used for VolumeRendering?

On Fri, Sep 23, 2022 at 1:44 PM Brutzman, Donald (Don) (CIV)
<brutzman at nps.edu <mailto:brutzman at nps.edu> > wrote:

Attendees: Dick Puk, Don Brutzman

1. We first reviewed the two recently posted Mantis issues regarding SVG and
QIF.  We also looked at a Mantis issue posted earlier this year relating to
scalable composition of really large X3D worlds.  Selected details follow.

a.	Mantis 1400: add Scalable Vector Graphics (SVG) to recommended image
formats for ImageTexture

https://www.web3d.org/member-only/mantis/view.php?id=1400

SVG references:

*
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.w3.or
g%2FGraphics%2FSVG&data=05%7C01%7Cbrutzman%40nps.edu%7C7c27ac4352b6456bb4e60
8da9e4342ff%7C6d936231a51740ea9199f7578963378e%7C0%7C0%7C637996309118717649%
7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwi
LCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=dNTi45a4RbClRy%2BDcu%2FoOyK7q7frspnDsqk
8UU1QaGQ%3D&reserved=0> https://www.w3.org/Graphics/SVG
* "SVG is a markup language for describing two-dimensional graphics
applications and images, and a set of related graphics script interfaces."

Dick estimation: thinks SVG is a 2D scene-graph definition language. It can
result as an image, though so can X3D.

This issue suggests that SVG be listed as a recommended (optional) format
that can be rendered as an ImageTexture, using the default presentation
settings of the SVG model.

Of note is that browsers are not forbidden from implementing SVG as an
ImageTexture format, and also that SVG-to-PNG converters are commonplace.

Of further note is that the DPS minutes already showed a use case for SVG as
ImageTexture, namely conversion of metadata information as a carefully
laid-out annotation image that is billboarded in context. Having direct SVG
rendering would eliminate the offscreen conversion step, permitting direct
integration of X3D models with other HTML/SVG web graphics.

Concern: don't want to overcomplicate the existing ImageTexture
functionality as a 2D array of pixels. Once generation of pixels becomes a
computational process, this is different functionality for the ImageTexture
node. This might raise further concerns about impact of ImageTexture
computational complexity in various profiles (such as Interchange Profile).

Possible alternate: define SvgTexture node? What fields would it have?

Suggested possible resolution:

a. Browsers are welcome to implement ImageTexture as an allowed url format
if they see fit,
b. SvgTexture ought to be designed and considered as a possible new node,
c. ComposedImageTexture (or somesuch) might be designed and considered as an
even-more general possibility for comuputational 2D imagery,
d. Following further practical experience, defer any specification-change
recommendations to future X3D4.1.

b.	Mantis 1401: aligning X3D4 LineProperties with Quality Information
Framework (QIF) specification

https://www.web3d.org/member-only/mantis/view.php?id=1401

Suggested resolution:

a. The concepts are directly aligned and overlapping, with some additions by
QIF.
b. This ISO standard does not appear to have been considered by SC24 or
JTC1.
c. Close scrutiny of both terms and definitions needs to be performed before
any changes might be recommended.
d. If changes are indeed warranted and acceptable, then they likely need to
first considered as part of the Registry of Items, specifically entries for
linestyle and hatchstyle.
e. At that point, amendment of X3D to stay aligned with Registry of Items
(or possibly add further styles independently) can be considered.
f. Defer to X3D 4.1.

Meanwhile note in Web3D current ballot comments the need to fix the table
erratum previously noted.

c.	Mantis 1192: 07.2.2 Bindable children nodes - Undefined results if
bindable node is under Switch or LOD is problematic

https://www.web3d.org/member-only/mantis/view.php?id=1192#bugnotes

Comment on 19775-1: Abstract X3D Definitions - V3.3
7.2.2 Bindable children nodes

<http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/component
s/core.html#BindableChildrenNodes>
http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/components
/core.html#BindableChildrenNodes

-----------------
Subject: Undefined results if bindable node is under Switch or LOD is
problematic

Spec sayeth:
"The results are undefined if a bindable node is bound and is the child of
an LOD, Switch, or any node or prototype that disables its children."

This leads to all manner of inconsistent problems among scenes. It also
means that Inline node (which may or may not include bindable nodes) has
undefined behavior under LOD/Switch/etc.

As a result, in addition to indeterminate X3D browser behavior, it means
that X3D scenes are not fully composable. That is contrary to X3D design
objectives.

Different prose and deterministic guidelines is needed in this section that
provides clear rules for binding/unbinding nodes when they become active
within LOD/Switch/etc. Small adaptations to current binding rules can likely
address this problem satisfactorily.

Related: Mantis issue 749

April 29:

Analysis during X3D Working Group call:

a. Switch would keep each binding stack aligned with whichever child was
active, thereby binding and unbinding nodes whenever the Switch level is
modified.

b. LOD would have all of its child bindable nodes on the binding stack
throughout, so that user experience was consistent. For example, it would
make no sense for Viewpoints to get arbitrarily unbound and bound, based on
range to viewer, as a user independently navigated through a scene.

c. LOD attempting to maintain author intent has access to all Viewpoint
nodes on binding stack, and range-to-viewer LOD transitions are either
flexible suggestions (browser-optimization control) or rigidly enforced
(forceTransitions field is TRUE). Thus if a node is subsequently bound by
user in a different inactive LOD child branch, then that binding event is
honored and that LOD child branch becomes the active child branch. This
binding event (and changed LOD child branch selection) takes precedence over
browser range/performance considerations, and also takes precedence over
whatever value is provided in forceTransitions field. (Example: selecting a
room Viewpoint while in a large building model).

d. NavigationInfo, Background and Fog binding stacks and responses to
binding events should behave identically to Viewpoint. Variations would be
exceedingly complex and not understandable. Consistency means that author
intent and user action always take precedence, for Switch and LOD response.

Spec editors work on integrating these principles as specification prose (we
are close already) and report back recommended changes to X3D working group.

Don's opinion: this will significantly help user-sensible scalability of
huge (perhaps Metaverse-scale) models using many Inline and prototype nodes,
enabling predictable and performant navigation and traversal throughout.

Today's session.

Alternatives deserving working-review consensus:

a. Recommending this clarification of undefined prior specification prose
might add important value, or might be construed as a technical change to
X3D4.0 that possibly requires future re-balloting as another X3D 4.0 DIS
(which is not an acceptable outcome).

b. If not balloted then this becomes an X3D4.1 issue.

c. Web3D might consider some alternative approach to strongly encourage
adoption of this clarified approach in order to further encourage greater
scalability of multi-world environments, and better alignment with shared
Metaverse design imperatives. For example, are we creating a Best Practices
Pending X3D 4.1 Approval document of some sort?

2. We only have 4 total issues to review as planned Web3D comments.  This
will occur during a single working-group meeting, 7 OCT.

Deadline for X3D Ballot comments:

*	OCT, Web3D comments to INCITS (U.S. National Standards Body
*	TBD OCT, INCITS comments to SC24
*	4 NOV, SC24 comments to ISO

No meeting currently planned for 30 SEP.

3. Bonus round: we worked on the "layer" diagram from recent meetings a bit
more.  Latest X3dApplicationStackLayerExamples is attached, all comments
welcome.

Have fun with X3D!

all the best, Don

-- 

Don Brutzman  Naval Postgraduate School, Code USW/Br        brutzman at nps.edu
<mailto: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 <http://faculty.nps.edu/brutzman> 

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