[x3d-public] Transform processing

[Holger Seelig]

When it comes to converting from glTF to X3D, I think I'm right. But yes, it's different from X3D to glTF, because there are center and scaleOrientation fields in X3D.

Best regards,
Holger

—
Holger Seelig
holger.seelig at yahoo.de


> Am 08.01.2026 um 13:37 schrieb Vincent Marchetti <vmarchetti at kshell.com>:
> 
> I disagree with the the statement that they are equivalent. Both the glTF and X3D transforms allow for scaling by axes-dependent factors along the x,y,z axes, however X3D allows, through the scaleOrientation field, a non-uniform scaling along an arbitrary set of 3 orthogonal axes. It's not possible to factor out this scaleOrientation in the same way that a rotation "center" can be factored out by rotating around the origin  and applying a counteracting translation.
> 
> It is possible to acheive the same rendering effect, in glTF, of a not-identity scaleOrientation, by specifying an empty node as the parent of your mesh, and applying a scale transform (in glTF) to the empty node. This is equivalent to nesting Transform nodes in X3D. But I think the original question to this thread was asking about the base capabilities in the glTF TRS system and X3D's Transform node.
> 
> Vince Marchetti
> 
> 
>> On Jan 8, 2026, at 5:39 AM, Holger Seelig via x3d-public <x3d-public at web3d.org> wrote:
>> 
>> Yes I can confirm, that the glTF specification is equivalent to X3D and will produce same results, and can easily be converted to a Transform node hierarchy.
>> 
>> Best regards,
>> Holger
>> 
>> —
>> Holger Seelig
>> holger.seelig at yahoo.de
>> 
>> 
>>> Am 08.01.2026 um 02:13 schrieb Don Brutzman via x3d-public <x3d-public at web3d.org>:
>>> 
>>> Looks functionally and mathematically equivalent to me.
>>> 
>>> A more detailed definition is probably available in the WebGL Specification. 
>>> 
>>> Browser builders can say whether they use transformation matrixes on the inside of their source, too. 
>>> 
>>> all the best, Don
>>> -- 
>>> X3D Graphics, Maritime Robotics, Distributed Simulation
>>> Relative Motion Consulting  https://RelativeMotion.info <https://relativemotion.info/>
>>> 
>>> 
>>> On Wed, Jan 7, 2026 at 19:20 Joe D Williams via x3d-public <x3d-public at web3d.org <mailto:x3d-public at web3d.org>> wrote:
>>>> can I get a comment about comparing these two text descriptions?
>>>> Thanks,
>>>> Joe
>>>> -----Original Message-----
>>>> From: Extensible 3D (X3D) Graphics public discussion <x3d-public at web3d.org <mailto:x3d-public at web3d.org>>
>>>> Sent: Dec 21, 2025 10:11 AM
>>>> To: <x3d-ecosystem-request at web3d.org <mailto:x3d-ecosystem-request at web3d.org>>, <x3d-public at web3d.org <mailto:x3d-public at web3d.org>>
>>>> Cc: Joe D Williams <joedwil at earthlink.net <mailto:joedwil at earthlink.net>>
>>>> Subject: [x3d-public] Transform processing
>>>> 
>>>> glTF
>>>> https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html#transformations
>>>> 
>>>> X3D
>>>> https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/components/grouping.html#Transform
>>>> 
>>>> 
>>>> Attached is cut from glTF standard and X3D standard.
>>>> I need to make sure these produce same result, except glTF has no center parameter.
>>>> Thanks and Best,
>>>> Joe
>>>> 
>>>> 
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