[x3d-public] Mantis [X3D 0001272]: glTF import needs to include metadata import

Michalis Kamburelis michalis.kambi at gmail.com
Wed Apr 28 05:03:40 PDT 2021


I have resolved my trouble: my Mantis comment was just too long.
Redirecting me into "Page Not Found" was Mantis's way of saying "you
need to write a shorter comment", it seems.

I have split the comment into 3 parts, and pasted into the Mantis issue OK now.

Regards,
Michalis


śr., 28 kwi 2021 o 12:38 Michalis Kamburelis
<michalis.kambi at gmail.com> napisał(a):
>
> I'm going to post here a comment that Don can hopefully paste in Mantis.
>
> Although I'm logged-in as a member, Mantis remains read-only for me.
> Trying to post a comment from
> https://www.web3d.org/member-only/mantis/view.php?id=1272 sends me to
> https://www.web3d.org/member-only/mantis/bugnote_add.php with "Page
> Not Found" information. I tried logging out + in on both Mantis and
> web3d.org, to no help.
>
> The answer to that glTF metadata issue:
>
> --------------
> From my point of view, this is "done". Namely, we have a way to
> express existing glTF metadata (mentioned in the description of this
> ticket) as X3D metadata. So import is possible.
>
> Castle Game Engine / view3dscene are doing that already: glTF "extras"
> are converted into X3D MetadataXxx nodes at import. As a demo, you can
> look into
>
> - https://github.com/castle-engine/demo-models/tree/master/blender/custom_properties
>
> - https://github.com/castle-engine/demo-models/tree/master/blender/custom_properties_2
>
> This shows Blender "custom properties" which are exported as glTF
> "extras" which are in turn converted into X3D MetadataXxx nodes when
> importing this glTF in CGE/view3dscene.
>
> The glTF "extras" are most important here, as they are a "free"
> key-value pairs that can be associated with various glTF objects, and
> so they are the closest equivalent of X3D MetadataXxx nodes.
>
> To break down the details from
> https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#asset-1
> :
>
> * copyright from glTF -> Done: the standard way to express it in X3D
> is META / <meta> information at the top-level of the X3D file.
>
> * generator from glTF -> Done: as above, the standard way to express
> it in X3D is META / <meta> information at the top-level of the X3D
> file
>
> * version from glTF -> Done: this could be converted to X3D META /
> <meta> , or ignored. Once glTF is imported, this information is not
> really relevant for person looking at resulting X3D nodes graph.
>
> * minVersion from glTF -> Done: as above, this could be converted to
> X3D META / <meta> , or ignored. Once glTF is imported, this
> information is not really relevant for person looking at resulting X3D
> nodes graph.
>
> * extensions from glTF -> Done: as above, this could be converted to
> X3D META / <meta> , or ignored. Once glTF is imported, this
> information is not really relevant for person looking at resulting X3D
> nodes graph.
>
> * extras from glTF -> Done: convert to X3D MetadataXxx nodes.
>
> To address @vmarchetti comment:
>
> I agree, that is: importing glTF (e.g. using """Inline { url
> "blabla.gltf" }""") shall NOT modify any "exterior Metadata nodes". As
> you describe, this would be problematic, when many files (with various
> formats -- X3D, glTF) are inlined, it would be confusing "where does
> metadata go". Fortunately, we have in X3D MetadataXxx nodes "tied" to
> any node at any level. So
>
> - When importing a glTF model with glTF "extras" attached to some glTF
> mesh, then we can generate X3D MetadataXxx nodes "tied" to the created
> X3D Shape/geometry.
>
> - The top-level X3D META / <meta> are already present at every model,
> so every Inline (whether it inlines glTF, X3D or anything else) is a
> new place to store per-model META / <meta> information already.
>
> So, X3D metadata (generated from glTF content) can (and should) stay
> inside the X3D nodes graph generated *from this glTF content*, and
> shall not "pollute" any X3D nodes outside.
> --------------
>
> Regards,
> Michalis



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