[x3d-public] X3D minutes19 June 2020: Mantis issues ongoing resolution - closer to draft X3D4 release

[Michalis Kamburelis]

> 1272            glTF import needs to include metadata import
> pending 1269 PBR, review next week!

This isn't related to PBR work in any way. My PR doesn't explicitly specify
how (and if, at all) glTF content is converted to X3D nodes.

Sure, you can use new X3D PhysicalMaterial to express glTF PBR materials,
but that's not something I mandate in any way in the X3Dv4 spec. (Even if
it's obvious for the implementors.) And I definitely do not want to mandate
any other details about converting glTF->X3D in my PR.

X3D 4.0 is not the right time to deal with this, IMHO. There are various
open questions about how to cooperate with glTF perfectly, and we have now
2 implementations that converge on some ideas, but are not 100%
synchronized (CGE and X3DOM). We are not yet at a place where we want to
mandate (in X3D spec) any particular conversion scheme glTF -> X3D.

> 1269            glTF physically based rendering PBR, advanced material
textures and lighting
> next week!

I expect to still work on my PR next week (including the weekend). I want
to finish things by the end of June. I may not be ready with them next
Friday (26 June).

As said in my other email, I would like to present my PR on first Friday in
July. So 3rd July. No next week.

> 1252            PointProperties node specification;
PointSet/LineSet/IndexedLineSet can contain Normal
> Mostly complete.  Sole remaining issue is whether PBR might affect
rendering prose.
> Need to do a final review when Physically Based rendering (Mantis 1269)
is finalized. The current opinion is that PointSet are considered unlit so
the rendering will not be affected by PBR.

I would say that PointSet with normals should be lit -- otherwise, what was
the point of specifying normals?

And all lighting models should be possible (so Material, UnlitMaterial,
PhysicalMaterial all make sense on such points).

The idea, as far as I understand, is that these points represent an
underlying object with surfaces, but are represented as points for
technical reasons (e.g. were obtained by 3D scanner). Thus you should make
these points and lines lit (when they have normals).

That is also what glTF does,
https://github.com/KhronosGroup/glTF/tree/master/specification/2.0#point-and-line-materials
. Points/lines with normal vectors are lit.

Regards,
Michalis
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