[x3d-public] event tracing

[Andreas Plesch]

Date: Sun, 30 Oct 2016 09:34:38 -0700

> From: Michael Aratow <maratow at noegenesis.com>
> To: x3d-public at web3d.org
> Subject: Re: [x3d-public] event utility usage, and event tracing
>         techniques
> Message-ID: <2037c542-880d-58ea-01b4-b03cf24f80c4 at noegenesis.com>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> If we take WebVR into consideration, these types of delays are significant.
>
> Do you anticipate problems?  End to end system delay in VR systems must
> be 20 milliseconds or less to avoid simulator sickness.
>

I am not sure these can be called delays. The actual rendering time of the
frame is not the bind time (of a viewpoint) but occurs afterwards.

Latency would be the time from some input via a controller to the time the
input has an effect on the rendering.

Not sure how to measure this. cobweb has timing measurements to show how
much time is spent for various processing steps.

Overall, I would expect that there will be a penalty for using the DOM to
control a scene, and that there is room for using a predictive capability
to reduce perceived latency.

A-Frame and three.js are trying hard to reduce latency. It will be
difficult to improve on or match their efforts.

-Andreas

 On 10/30/16 7:59 AM, Andreas Plesch wrote:> Hello,>

> > cobweb_dom v0.7 is now available. It has full support for
> > ProtoInstance nodes and basic event tracing capability.
> >
> > v0.7 requires the latest development cobweb.js, eg cobweb > 2.3 .
> >
> > Event tracing to the console can be enabled by providing a 'trace'
> > attribute to the X3DCanvas element (with any value).
> >
> > All output x3d events are logged. Here is an example:
> >
> > 1477837418917000: Background  x3d_isBound: true
> > 1477837418918000: Background  x3d_bindTime: 1477837418.9007943
> > 1477837418919000: Viewpoint  x3d_isBound: true
> > 1477837418920000: Viewpoint  x3d_bindTime: 1477837418.9007943
> > 1477837421509000: CylinderSensor aroundX x3d_isOver: true
> > ...
> >
> > (using
> > https://andreasplesch.github.io/cobweb_dom//tests/
> interactiveTransformations.xhtml
> > )
> >
> > The frontal time stamp is the DOM event creation time stamp in
> > microseconds produced by the web browser and available to DOM event
> > listeners.
> > It is interesting to see the difference between the time stamp and say
> > the bindTime of the Background node, 18.918s - 18.901s = 17 ms
> > or for Viewpoint: 18.920 - 18.901 = 19 ms.
> > So it takes a bit for cobweb to call the event callback which creates
> > the DOM event.
> > When a DOM event listener captures the event, it may be a little later
> > again.
> > With a fps of 30, a frame lasts 33ms.
> > It will be interesting to compare what time stamps and values are
> > reported with the x3d-edit trace scripts.
> >
> > -Andreas
> >
> >
> >
> > On Sat, Oct 29, 2016 at 8:00 PM, Andreas Plesch
> > <andreasplesch at gmail.com <mailto:andreasplesch at gmail.com>> wrote:
> >
> >     On Oct 29, 2016 6:20 PM, "Don Brutzman" <brutzman at nps.edu
> >     <mailto:brutzman at nps.edu>> wrote:
> >     >
> >     > On 10/29/2016 2:21 PM, Andreas Plesch wrote:
> >     >>
> >     >> [...]
> >     >>
> >     >> Since logging all fields for all nodes becomes quickly a bit
> >     overwhelming, it would be a nice touch to be able select in the
> >     GUI which fields are traced (by default all).
> >     >
> >     >
> >     > excellent idea.  not easily accomplished with current setup, but
> >     will keep it in mind as a future feature in X3D-Edit.
> >     >
> >     > for that matter, couldn't someone someday somewhere create such
> >     a widget in HTML that listened to all ROUTEs, as selected?  8)
> >
> >     It should be possible find all elements referenced by fromNode
> >     attributes in ROUTE elements and attach event listeners with
> >     handlers which just log to the console. Let me give it a try.
> >
> >     Andreas
> >
> >
> >
> >
> > --
> > 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
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-- 
Andreas Plesch
39 Barbara Rd.
Waltham, MA 02453
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