[x3d-public] V4.0 Open discussion/workshop on X3D HTML integration

Andreas Plesch andreasplesch at gmail.com
Mon Jun 6 09:58:06 PDT 2016

Hi Don,

On Sun, Jun 5, 2016 at 2:32 PM, Don Brutzman <brutzman at nps.edu> wrote:

> Wondering if the x3dom dual-graph page dom structures align with the draft
> work on Shadow DOM at W3C.
> https://www.w3.org/TR/shadow-dom

The shaw-dom spec is being upstreamed to the dom spec.


This is a good resource, since it also explains the web page DOM in detail.

I am not sure if the shaw-dom aligns with the dual graph approach because
the shadow-dom is still a dom structure and not a scene graph. I think it
may be still necessary to define a x3d dom and interfaces similar to

I'm hoping that John Carlson gets a chance to look at whether his JSON
> prototype expander might be adaptable as part of x3dom - that would be
> pretty valuable.  Although Fraunhofer has outstanding prototype support in
> their Instant Reality engine, it has never been clear why that code can't
> simply be applied in x3dom as well.  Certainly a consistent approach would
> seem to make both codebases more coherent and maintainable for them.  If
> Fraunhofer refuses to adapt or release the Instant Reality prototype code
> then we will just have to do it ourselves... John's work seems like a big
> step in that direction

Well, I would not have a good idea on how to implement prototypes in x3dom.
Not sure if the Instant Reality code would really help. One idea may be to
see if there is an existing declarative way to register new custom elements
using web components, and extend that. But I do not think there is.


> Also thanks for pointing out important questions about Fraunhofer's
> stewardship of the X3DOM project.  It will be good to learn more about
> their intentions so that our community can align effectively.  There has
> been no handoff.

Well, there have been no fixes or updates to the code base on github for a
long time and a recent issue response suggested that FHG considers x3dom
community supported.

> Regarding the X3D event system: a changing value of any field in any node
> can be sent as an input to any field in any node, as long as types strictly
> match (apples to apples).  Rephrased: a ROUTE passes a time-stamped value
> from one node to another. Internal to an X3D scene graph, that has been
> implemented dozens of times.  Seems extremely simple.

> External to an X3D scene graph, meaning via a browser using the Scene
> Access Interface (SAI), mechanisms are similarly well defined.  Since the
> DOM is string based, and since any X3D event value can be expressed as a
> string, it seems like we have a straight connect-the-dots approach awaiting
> us.  Forgive me for using a four-letter word, but if interested individuals
> might actually _read_ the HTML5/DOM and X3D specifications, then the
> answers to most implementation & alignment questions are likely spelled out
> for us.

https://dom.spec.whatwg.org/#events would be HTML5 side of events.

Is the statement at https://dom.spec.whatwg.org/#action-versus-occurance
compatible with

It will be great to get our wiki organized for clarity and go-forward
> action on these important X3D version 4 design issues.
> Thanks for letting us know about your other explanations - very
> interesting!  8)

Yeah, VR is not really part of this discussion (although it could be a V4
topic) .

> Looking forward to continuing, sustainable evolution and progress together.

I think if there is way to open spec. drafting more along the lines of
other www spec. efforts on github, there is a chance to attract a wider
community for more man power which would be much needed.


> v/r Don
> On 6/3/2016 11:40 AM, Andreas Plesch wrote:
>> Hi Roy, group,
>> I would like to join the 2h open discussion on Wednesday but will be in
>> an all day meeting, actually on the West Coast.
>> These are excellent questions and trying to answer them will help getting
>> closer.
>> Here are some thoughts.
>> The discussion on introducing an id field seemed to point towards the
>> need to have fuller integration in the sense that it is difficult to
>> isolate features. It may be necessary to define a x3d dom similar to the
>> svg dom, with the corresponding interfaces. svg is very successful on the
>> web but it took a long time to arrive there.
>> x3dom has a dual graph approach. There is the x3d graph and in parallel
>> the page dom graph which are kept in sync but are both fully populated.
>> Johannes would know better how to explain the concept.
>> It looks like FHG decided that x3dom is now considered community (only?)
>> supported. This probably means it will be out of sync as newer web browsers
>> arrive, or webgl is updated.
>> I explored Aframe a bit more. It will be popular for VR. It is still in
>> flux and evolves rapidly. The developers (mozilla) focus on its basic
>> architecture (which is non-hierarchical, a composable component system) and
>> expects users to use javascript to develop more advanced functionality (in
>> the form of shareable components). So it is quite different, fun for
>> developers, and for basic scenes easy for consumers. Since most mobile VR
>> content at this point is basic (mostly video spheres and panos), it is a
>> good solution for many.
>> (As a test I also implemented indexedfaceset as an Aframe component, and
>> it was pretty easy - after learning some Three.js. So it would be possible
>> to have x3d geometry nodes on top of aframe. Protos, events and routes are
>> another matter but also may not be impossible).
>> There is still space for x3d as a more permanent, and optionally
>> sophisticated 3d content format on the web.
>> Event system: My limited understanding is that on a web page, the browser
>> emits events when certain things happen. Custom events can also be emitted
>> by js code (via DOM functions) for any purpose. (All ?) events have a time
>> stamp and can have data attached. Then, events can be listened to. There is
>> no restriction to listening, eg. all existing events are available to any
>> listener. A listener then invokes a handler which does something related to
>> the event. js code can consume, cancel, or relay events as needed (via DOM
>> functions). It is not unusual that many events are managed on a web page.
>> events can be used to guarantee that there is a sequence of processing.
>> So how does the x3d event system relate ? There is a cascade, and
>> directivity. How long does an event live ? one frame ? Until it fully
>> cascaded through the scene graph ?
>> Since x3dom and cobweb are currently the only options, from a practical
>> stand point a question to ask may be this: what is needed to make x3dom and
>> cobweb easy to use and interact with on a web page ? Typically, the web
>> page would provide an UI, the connection to databases or other sources of
>> data, and the x3d scene is responsible for rendering, and interacting with
>> the 3d content. For VR, the UI would need to be in the scene, but
>> connections and data sources would still be handled by the web page.
>> Cobweb in effect allows use of the defined SAI functions. Is it possible
>> to define a wrapper around these functions to allow a DOM like API
>> (createElement, element.setAttribute .. element = null) ? It may be since
>> they are similar anyways and it would go a long way. But it still would not
>> be sufficient to let other js libraries such as D3.js or react control and
>> modify a scene since they would expect x3d nodes to be real DOM elements.
>> VR: A current issue is control devices. It would be probably useful to go
>> over the spec. and see where there is an implicit assumption that mouse or
>> keyboard input is available. VR HMDs have different controls (head position
>> and orientation(pose), one button) and hand held controllers (gamepads,
>> special sticks with their own position/orientations) or the tracked hands
>> themselves become more popular. In VR, you do want to your hands in some
>> way.
>> Perhaps, it makes sense to have <Right/LeftHand/> nodes paralleling
>> <Viewpoint/> with position/orientation fields which can be routed to
>> transforms to manipulate objects ?
>> How  a browser would feed the <Hand> nodes would be up to the browser.
>> InstantReality has a generic IOSensor.
>> Andreas
>> On Wed, Jun 1, 2016 at 4:53 PM, Roy Walmsley <roy.walmsley at ntlworld.com
>> <mailto:roy.walmsley at ntlworld.com>> wrote:
>>     *X3D HTML integration____*
>>     *__ __*
>>     *X3D V4.0 Open discussion/workshop____*
>>     *__ __*
>>     *June 8^st 2016 at 1500-1700 UTC (0800-1000  PDT, 1500-1700 GMT,
>> 1700-1900 CET)____*
>>     *__ __*
>>     A discussion/workshop on version 4.0 of X3D which aims to consider
>> the following questions, and suggest potential solutions.____
>>     __ __
>>     __·         __What level of X3D integration into HTML5 do we want?____
>>     __o   __Do we want to be fully integrated like SVG?____
>>     __·         __Do we want/need a DOM spec? If so:____
>>     __o   __Which DOM version should it be based on?____
>>     __o   __Do we want to fully support all DOM/HTML features?____
>>     __·         __Do we want to maximize the backwards compatibility of
>> V4.0 with V3.3? Or break away completely?____
>>     __o   __Do we want to retain SAI?____
>>     __·         __What features do we want? For example,____
>>     __o   __How is animation to be handled? The X3D way of TimeSensor and
>> ROUTEs, or an HTML way, such as CSS3 animations, or else JavaScript?____
>>     __o   __How is user interaction to be handled? The X3D way of
>> Sensors, or the HTML way with event handlers?____
>>     __o   __Do we need any different nodes? One example might be a mesh
>> node?____
>>     __o   __Do we want Scripts and Prototypes in HTML5?____
>>     __o   __How do we want to handle styling?____
>>     __·         __What profile(s) do we need for HTML?____
>>     __ __
>>     The discussion/workshop will be held on the Web3D teleconference
>> line. It is open to anyone interested in X3D. Please e-mail
>> roy.walmsley at ntlworld.com <mailto:roy.walmsley at ntlworld.com> or
>> brutzman at nps.edu <mailto:brutzman at nps.edu> for teleconference
>> details.____
>>     __ __
>>     If you can’t join in the discussion, but would still like to
>> contribute to the debate, your comments would be welcomed on the X3D public
>> mailing list at x3d-public at web3d.org <mailto:x3d-public at web3d.org>.____
>>     __ __
>>     Roy Walmsley____
>>     X3D WG Co-chair____
>>     __ __
>> --
>> Andreas Plesch
>> 39 Barbara Rd.
>> Waltham, MA 02453
>> _______________________________________________
>> x3d-public mailing list
>> x3d-public at web3d.org
>> http://web3d.org/mailman/listinfo/x3d-public_web3d.org
> 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
> http://faculty.nps.edu/brutzman

Andreas Plesch
39 Barbara Rd.
Waltham, MA 02453
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