[x3d-public] X3D V4 Draft Requirements Proposal

[Leonard Daly]

I included OBJ because it is a very popular format for the exchange of 
geometry and normal information. I have only seen it with triangles. I 
am in complete agreement with Michalis about limiting it's scope.


Leonard Daly

On 3/29/2017 3:50 AM, Michalis Kamburelis wrote:
> 2017-03-28 5:05 GMT+02:00 Andreas Plesch <andreasplesch at gmail.com>:
>> Support for multiple geometry formats, including OBJ, glTF
> I applaud this idea, as we need interoperability, and glTF is a nice standard.
>
> But I would remove OBJ from this list, or be *careful* what parts of
> the OBJ are necessary to be supported.
>
> - The OBJ is an old format. It doesn't have many features nice for
> modern rendering (like a specification of shading suitable for modern
> GPUs). And it does have some features that are unhandy, and were
> probably really useful only by the initial Wavefront OBJ
> implementation (trace_obj).
>
> - The OBJ specification is not officially maintained by anyone, I
> think. It's not updated. The creators of it, and the original software
> implementing it, are closed now.
> (https://en.wikipedia.org/wiki/Wavefront_Technologies ,
> https://en.wikipedia.org/wiki/The_Advanced_Visualizer ). Noone since
> then has taken the effort to update the OBJ specification in any way,
> as far as I know.
>
> - Although it has a specification
> http://www.martinreddy.net/gfx/3d/OBJ.spec , most implementations
> treat it more like a "de-facto" standard, implementing a different
> subsets of the format, whatever seems useful. There are features in
> OBJ format that are widely supported (vertexes with normals, tex
> coords), and there are features not supported by any existing
> implementation (I have not seen yet an implementation that supports
> Bezier patches defined in OBJ files; or one that supprts d_interp or
> trace_obj).
>
> Bottom line: While OBJ is a popular format, I would either discourage
> from using it (we made X3D for a reason --- it's really better on all
> accounts), or at least specify only a precise subset of OBJ features
> required to be supported.
>
> Regards,
> Michalis
>


-- 
*Leonard Daly*
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Chair
President, Daly Realism - /Creating the Future/
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