[x3d-public] Specification review progress: PNG3, Tangent node, HAnim weekly progress
Michalis Kamburelis
michalis.kambi at gmail.com
Fri Jul 4 19:40:11 PDT 2025
Great, thanks for applying.
Note that you can remove now the sentence near the end,
"""Each element in the vector array provides a unit XYZ vector defining
a tangent direction on the surface, together with a W component whose sign
value (-1 or +1) indicates the handedness of the tangent base."""
The beginning of my prose also contains this, I just split that 1 sentence
into 2 sentences with a bit more information.
As for:
- " Still need an overview description for node itself"
- " If one starts with Tangent node and then goes to X3D lighting
equations, where would they find it?"
-> hm, I am not clear what more do you think is necessary here, but I am
happy to work on what we have and add what you think is needed. The
"overview" for me is my sentence
"""Tangent vectors, if provided using this node, determine the tangent
space in which the normalmaps (specified in the normalTexture fields of
various material nodes) are specified."""
-- maybe you want to move this sentence earlier, to make it clearer that
this is an overview?
I'll try to join Web3d call next Friday too, so maybe we can finalize this
together during the call :)
Thanks and regards,
Michalis
pt., 4 lip 2025 o 23:29 Don Brutzman <don.brutzman at gmail.com> napisał(a):
> Thanks for review.
>
>
> 1. Agreed, corrected.
> 2. Added prose. Still need an overview description for node itself.
> Have pushed resulting update online for ongoing review.
> 3. Adjusted as an editors' note for now... we do need to mention this
> point, hopefully clearly
> 4. Very good. All changes committed to github and updated at
> * 11.4.13 Tangent
>
>
> - *
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/rendering.html#Tangent
>
>
>
> 5. Sorry but we do seem to need more... If one starts with Tangent
> node and then goes to X3D lighting equations, where would they find it?
>
>
> - *
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/lighting.html
>
>
> v/r Don
> ------------------------------
> *From:* Michalis Kamburelis <michalis.kambi at gmail.com>
> *Sent:* Friday, July 4, 2025 12:29 PM
> *To:* Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org
> >
> *Cc:* Richard Puk <puk at igraphics.com>; Don Brutzman <
> don.brutzman at gmail.com>
> *Subject:* Re: [x3d-public] Specification review progress: PNG3, Tangent
> node, HAnim weekly progress
>
> Thanks for pursuing Tangent node in X3D! Comments for the node prose (
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/rendering.html#Tangent
> , section "11.4.13 Tangent" ):
>
> 1. I guess it was just a copy-paste mistake that node declaration in
> section "11.4.13 Tangent" says """TriangleFanSet :
> X3DComposedGeometryNode""" :)
>
> You most likely wanted to say there """Tangent : X3DTangentNode""".
>
> 2. For the """TODO node definition and description.""" -- I wrote a
> proposed prose, and placed it in
> https://github.com/michaliskambi/x3d-tests/wiki/Tangent-node-in-X3D . See
> section "Prose for spec", from "Each element in the vector array provides a
> unit XYZ vector defining a tangent direction on the surface."....
>
> I welcome proposals to make it shorter :) I also welcome
> double-checking what I wrote!
>
> 3. I would remove from spec the sentence """NOTE The Tangent node
> functionality has no relation to Normal node functionality.""". The tangent
> node is different, but sometimes related to normals, as my prose linked
> above also explains. So this sentence could be a bit confusing, at least it
> is to me. Maybe we don't need this sentence, or the intention behind it
> should be phrased differently?
>
> 4. The sentence """NOTE See the GLTF specification for further technical
> details.""" is good, keep it, that is indeed (one of the) design goals here.
>
> 5. As for question """How does Tangent node affect the 17.2.2 Lighting
> model? Consistent rendering is necessary. """ -- I think we don't need to
> say anything more, actually. The lighting spec already says """N =
> normalized normal vector at this point on geometry. [...] It is modified by
> the normalTexture providing normals in the tangent space (see
> X3DOneSidedMaterialNode definition).""" and that's actually enough, I think.
>
> Regards,
> Michalis
>
> pt., 27 cze 2025 o 18:47 Don Brutzman via x3d-public <x3d-public at web3d.org>
> napisał(a):
>
> Dick and I held another weekly specification editors' meeting.
>
> After a tumultuous week checking out for retirement, I finally have some
> things for us to review.
>
> a. *PNG3*
>
> - X3D Architecture draft v4.1, clause 18 Texturing component, 18.2.2
> Texture map image formats
> -
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/texturing.html#TextureMapImageFormats
> - X3D Architecture draft v4.1, clause 18 Texturing component,18.4.2
> MovieTexture
> -
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/texturing.html#MovieTexture
> - Normative references: W3C_PNG
> -
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/references.html#W3C_PNG
>
>
> Of note, PNG3 is now final: 🙂
>
>
> - *Portable Network Graphics (PNG) Specification (Third Edition)
> <https://www.bing.com/ck/a?!&&p=85f7cc4f26f850c116f5b9afcb2987d31a5a02381bf6cb7b802a97c05394ec22JmltdHM9MTc1MDk4MjQwMA&ptn=3&ver=2&hsh=4&fclid=0999e3c9-3acb-60ad-25bf-f62b3b486183&psq=w3.org+png+third+edition&u=a1aHR0cHM6Ly93d3cudzMub3JnL1RSL3BuZy0zLw&ntb=1>*
> - W3C Recommendation, 24 June 2025
> - https://www.w3.org/TR/png-3/
>
>
>
> - PNG Third Edition, Implementation Report (includes animated PNG
> image)
> - https://w3c.github.io/png/Implementation_Report_3e/
> -
> https://w3c.github.io/png/Implementation_Report_3e/img/APNG-Icos4D.png
>
>
>
> b. *Tangent node*
>
>
> - Mantis 1496: add Tangent node to support advanced rendering
> capabilities of glTF
> - https://mantis.web3d.org/view.php?id=1496
>
>
> with
>
> - Michalis Kamburelis: Tangent node in X3D
> - https://github.com/michaliskambi/x3d-tests/wiki/Tangent-node-in-X3D
>
>
>
> - Holger Seelig: Tangent node
> - https://create3000.github.io/x_ite/components/rendering/tangent/
>
> - X3D Architecture draft v4.1, clause 11 Rendering component
> - 11.3.2 X3DComposedGeometryNode
> -
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/rendering.html#X3DComposedGeometryNode
> - 11.3.7 X3DTangentNode
> -
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/rendering.html#X3DTangentNode
> - 11.4.13 Tangent
> -
> https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/components/rendering.html#Tangent
> And related implementing nodes
>
>
> Here is the preliminary draft for Tangent node. *Dear rendering
> experts: more prose needed for draft specification that describes this
> functionality!*
> *11.4.13 Tangent*
>
> TriangleFanSet : X3DComposedGeometryNode {
> SFNode [in,out] metadata NULL [X3DMetadataObject]
> MFVec4f [in,out] vector []
> }
>
> *TODO* node definition and description.
> Each element in the *vector* array provides a unit XYZ vector defining a
> tangent direction on the surface, together with a W component whose sign
> value (-1 or +1) indicates the handedness of the tangent base.
> NOTE The Tangent node functionality has no relation to Normal node
> functionality.
> NOTE See the GLTF <http://../references.html#GLTF> specification for
> further technical details.
> *TODO * How does Tangent node affect the 17.2.2 Lighting model
> <http://lighting.html#LightingModel>? Consistent rendering is necessary.
>
> c. Discuss *HAnim progress* on weekly calls - encouraging! 🙂
>
> - Many diverse topics (such as single/double floating-point precision,
> etc.) can go into the use-case modeling guidelines
> - Iterative improvement is always best
> - We will stay focused on refinements to HAnim 2.0, and identify
> larger issues (such as Coveroid/Clothing) for the HAnim working group
>
>
> d. *Schedule*
>
> - No call next Monday - am retiring!
> - Next Wednesday call: final review for annual ISO meeting in
> Alexandria VA the following week
> - Next Friday call: also cancelled, July 4 Independence Day in USA.
>
>
> Aloha! v/r Don
>
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