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

Don Brutzman don.brutzman at gmail.com
Fri Jun 27 09:46:25 PDT 2025


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
[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<../references.html#GLTF> specification for further technical details.
TODO How does Tangent node affect the 17.2.2 Lighting model<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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