[x3d-public] Specification review progress: PNG3, Tangent node, HAnim weekly progress

Tue Jul 22 09:28:58 PDT 2025

Some additional interesting summary information about PNG3:  approaching
TIFF capabilities, also includes HDR.

   - Portable Network Graphics (PNG) Specification (Third Edition) is now a
   W3C Recommendation
   - W3C News, 24 June 2025
   -

   The PNG Working Group <https://www.w3.org/groups/wg/png/> published Portable
   Network Graphics (PNG) Specification (Third Edition)
   <https://www.w3.org/TR/2025/REC-png-3-20250624/> as a W3C
   Recommendation. This document describes PNG (Portable Network Graphics), an
   extensible file format for the lossless
   <https://www.w3.org/TR/2025/REC-png-3-20250624/#dfn-lossless>, portable,
   well-compressed storage of static and animated raster images. PNG provides
   a patent-free replacement for GIF and can also replace many common uses
   of TIFF. Indexed-color
   <https://www.w3.org/TR/2025/REC-png-3-20250624/#3indexedColour>,
   greyscale <https://www.w3.org/TR/2025/REC-png-3-20250624/#dfn-greyscale>,
   and truecolor
   <https://www.w3.org/TR/2025/REC-png-3-20250624/#3truecolour> images are
   supported, plus an optional alpha channel. Sample depths range from 1 to 16
   bits.

   The Third Edition adds Animated PNG and High Dynamic Range (HDR) PNG.
   -
   https://www.w3.org/news/2025/portable-network-graphics-png-specification-third-edition-is-now-a-w3c-recommendation/

*These capabilities offer significant additional opportunities for X3D4
model authors to achieve the highest possible rendering quality.*

PNG3 has been added to recommended changes X3D draft version 4.1
Architecture.

   - X3D Architecture, 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,  2 Normative references
   -
   *W3C_PNG* Portable Network Graphics (PNG) Specification
   <https://www.w3.org/TR/png-3>, Third Edition, *World Wide Web Consortium
   (W3C) Recommendation*, 25 June 2025.
   -
   https://www.web3d.org/specifications/X3Dv4Draft/ISO-IEC19775-1v4.1-CD//Part01/references.html#W3C_PNG
   - Mantis1497: PNG3 standard available, includes support for .pnga
   animation capabilities
   - https://mantis.web3d.org/view.php?id=1497

Have fun with X3D4 and PNG3!  😀👍

all the best, Don

On Fri, Jun 27, 2025 at 9:46 AM Don Brutzman <don.brutzman at gmail.com> wrote:

> 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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