[x3d-public] Clarifications on "glTF Interactivity Extensions Approach Finalization: Your Feedback Needed!"
Joe D Williams
joedwil at earthlink.net
Mon Jun 9 13:00:05 PDT 2025
> I do know that TouchSensor affects sibling geometry.
Good, that is a clue, but notice the VisibilitySensor can appear anywhere, containing nothing or something and works sort of like the ProximitySensor. For example using Visibility instead of Proximity to start a timer.
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/environmentalSensor.html#VisibilitySensor
https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/environmentalSensor.html#ProximitySensor
Thanks,
Joe
-----Original Message-----
From: John Carlson <yottzumm at gmail.com>
Sent: Jun 9, 2025 12:12 PM
To: Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org>
Cc: Leonard Daly <Leonard.Daly at realism.com>, Joe D Williams <joedwil at earthlink.net>
Subject: Re: [x3d-public] Clarifications on "glTF Interactivity Extensions Approach Finalization: Your Feedback Needed!"
I apologize that I can’t dig deeper on this. Joe, I think I’m missing something. I tried to read the VisibilitySensor standard. AFAICT, there’s no real geometry associated with the sensor, just a size and center (a volume, not geometry). The sensor may be moved with parent transforms. The key to the sensor is that isActive is turned FALSE or TRUE, and enterTime and exitTime events are generated.
So, yes, the difference in names (visible/visibility) with the same semantics for shape/geometry is important, but I’m not sure if it will impact much operationally. I did note that the visible field is on the shape node in x3d. I think you mentioned that the visibility property is on the geometry in glTF.
I realize that the VisibilitySensor may affect parent or sibling geometry, I just don’t see that in the standard. I haven’t tried very hard! I do know that TouchSensor affects sibling geometry. Clarification on whether there’s geometry associated with VisibilitySensor is welcome.
Perhaps glTF is distinguishing rendering from interactivity, and thus in interactivity, it’s called visibility? Is there a visible property elsewhere in glTF?
John
On Mon, Jun 9, 2025 at 10:59 AM Joe D Williams via x3d-public <x3d-public at web3d.org (mailto:x3d-public at web3d.org)> wrote:
when I looked at the Interactivity proposal, the only potential problem I saw was that of naming. The concept seemed to use the term visibility=true/false to indicate whether the geometry was rendered or not.
.
In x3d we use the term visible=true/false which is a property of the Shape geometry, to determine if the geometry is visible (rendered) or not.
X3d uses the term visibility in a sensor name that signals if the geometry is within visual range of the current viewpoint.
This is a small difference, but important.
So in x3d an element of geometry can be designated by a sensor, the VisibilitySensor, to signal visibility from the viewpoint, where the event is true when the geometry is within visual range of the viewpoint. The subject geometry is parented by a sensor node that signals true when the viewpoint range includes the geometry..
Also the x3d Shape node includes a property, visible=true/false, that defines whether the geometry is visible (rendered) independent of the viewpoint position.
In x3d the user can (1) control whether the shape is visible (rendered) or not using visible=true/false,
and (2) detect whether the Shape is within range of the viewpoint using VisibilitySensor,
regardless of whether the Shape visible property is true or false.
.
Hoping the difference between x3d use of visibility and visible is clear,
Joe
-----Original Message-----
From: Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org (mailto:x3d-public at web3d.org)>
Sent: Jun 9, 2025 7:44 AM
To: Leonard Daly <Leonard.Daly at realism.com (mailto:Leonard.Daly at realism.com)>
Cc: Brutzman, Donald (Don) (CIV) <brutzman at nps.edu (mailto:brutzman at nps.edu)>, Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org (mailto:x3d-public at web3d.org)>
Subject: Re: [x3d-public] Clarifications on "glTF Interactivity Extensions Approach Finalization: Your Feedback Needed!"
Thanks for the clarifications Leonard.
We are certainly happy for glTF progress in this area, and for emerging support and conversions of the interaction extension capabilities. Steadily increasing compatiblity and interoperability with glTF evolution remains a demonstrated goal for continuing X3D4 evolution.
The review posted by Dick and I is written from the perspective of Web3D Consortium IPR policy and preparation of the X3D ISO standards. No criticism is intended or implied. As specification editors, we are simply careful to never require adoption of licensed technology that is not declared royalty free for any purpose. We are further careful not to make assertions on behalf of current or future X3D users, since they speak for themselves.
The Khronos Group and the Web3D Consortium have some different but compatible policies. Cooperation has worked well for all parties, both via direct liaison partnerships and via ISO standardization. You know the following reference, others may find it useful as well.
* Web3D Consortium Intellectual Property Rights (IPR) Policy
* https://www.web3d.org/sites/default/files/page/Join%20the%20Web3D%20Consortium/Web3D_IPR.pdf
Looking forward to steady forward progress. Your helpfulness is appreciated, again thanks.
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
From: x3d-public <x3d-public-bounces at web3d.org (mailto:x3d-public-bounces at web3d.org)> on behalf of Leonard Daly via x3d-public <x3d-public at web3d.org (mailto:x3d-public at web3d.org)>
Sent: Friday, June 06, 2025 1:55 PM
To: x3d-public at web3d.org (mailto:x3d-public at web3d.org) <x3d-public at web3d.org (mailto:x3d-public at web3d.org)>
Cc: Leonard Daly <Leonard.Daly at realism.com (mailto:Leonard.Daly at realism.com)>
Subject: Re: [x3d-public] Clarifications on "glTF Interactivity Extensions Approach Finalization: Your Feedback Needed!"
I think a few of the statements are incorrect or not clear. My comments strictly address those items that discuss Khronos-developed material.
On 6/6/2025 10:33 AM, Brutzman, Donald (Don) (CIV) via x3d-public wrote:
Strategic Review
* The work looks thorough and consistently high quality, matching other Khronos specifications.
Thank you. I will pass on this praise.
* The Khronos license terms appear to be unchanged since our prior review.
* Use of the extension requires either membership as an Adopter of Khronos IPR policy, or else " express prior written permission of Khronos."
* Patented materials are included in the specification (though not specifically identified).
* https://github.com/KhronosGroup/glTF/blob/interactivity/extensions/2.0/Khronos/KHR_interactivity/Specification.adoc#foreword
There has been no change to the Khronos IP policy. The full first paragraph of statement in the draft specification is:
This specification is protected by copyright laws and contains material proprietary to Khronos. Except as described by these terms, it or any components may not be reproduced, republished, distributed, transmitted, displayed, broadcast, or otherwise exploited in any manner without the express prior written permission of Khronos.
Note the important clause at the beginning of the second sentence: "Except as described by these terms". The subsequent paragraphs provide the terms, specifically:
Khronos grants a conditional copyright license to use and reproduce the unmodified specification for any purpose, without fee or royalty, EXCEPT no licenses to any patent, trademark or other intellectual property rights are granted under these terms. Parties desiring to implement the specification and make use of Khronos trademarks in relation to that implementation, and receive reciprocal patent license protection under the Khronos IP Policy must become Adopters... [bolding is mine - ld]
If you have no interest in using Khronos trademarks or receiving reciprocal patent licenses, then you do not need to become an "Adopter".
Note that the specification document is licensed as "CC-BY 4.0".
Technical Review
* This extension is for JavaScript programmers who want to animate glTF models.
There is no programming required for the Interactivity extension. glTF viewers that correctly implement the specification handle the data that is stored in the glTF file structure and act according to that data. The data is not code (JavaScript or anything else). Also not that "animate" means any kind of change to the model or environment.
Leonard Daly
...
Sincerely, Don Brutzman and Dick Puk
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 (https://faculty.nps.edu/brutzman)
--
Leonard Daly
3D Systems Engineering
President, Daly Realism - Creating the Future
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