[x3d-public] Feature comparison of glTF and X3D as Interchange Formats

Leonard Daly Leonard.Daly at realism.com
Thu Sep 21 14:40:51 PDT 2017


Thank you Michalis and Mike. I have incorporated your comments into the 
post by expanding the top section and highlighting that the comparison 
just reflects the specifications and the X3D Interchange profile. I also 
added more explanation for the choice of comparison factors.

The request was not explicitly for the Interchange Profile, but why/how 
someone would choose between these two formats. Since higher level X3D 
Profiles include a lot of run time and glTF does not include any, it 
would not be a fair comparison -- it wouldn't even be relevant. Someone 
might need to work in a specific environment which would preclude X3D's 
runtime.

A lot depends on what a developer needs to do. For example, if the 
developer is someone at Autodesk that works on Maya, the 
modeling/texturing/animation capabilities are critical. A required 
run-time is a hindrance. A developer at a web company wants to know how 
well things will work in a DOM-integrated browser environment. X3D (as 
described in the spec) cannot be considered because it is not 
DOM-integrated. If the developer is building a stand-along environment, 
then glTF can only address the modeling part as it does not have a 
run-time.


Leonard Daly



On 9/21/2017 7:26 AM, Michael Aratow wrote:
> Thanks Michalis!  I am one of those readers, since I didn't read the 
> fine print or Leonard's explanatory sentence appropriately!
>
> I wonder why the request was just for interchange profile? Wouldn't a 
> true comparison be of all the features supported by the complete spec 
> of each?  That's what I would think a developer would be wanting to know.
>
>
> On 9/21/17 5:32 AM, Michalis Kamburelis wrote:
>> 2017-09-20 16:14 GMT+02:00 Leonard Daly <Leonard.Daly at realism.com>:
>>> In response to a request, I wrote an article comparing features of 
>>> glTF to
>>> X3D Interchange Profile. Most of the comparisons include links to 
>>> illustrate
>>> the capabilities. The article is online at
>>> http://realism.com/blog/gltf-x3d-comparison. It includes comparison to
>>> features and capabilities of both and a few items showing the extent of
>>> support in other packages.
>> Thank you. That is very informative.
>>
>> The only thing I would complain is that some readers may not realize
>> that this is only talking about X3D in Interchange profile. Some
>> features ("Quad surface model", "Mesh skin", "Custom Shaders", "Joint
>> animation") are actually available in X3D, just not in the
>> "Interchange" profile. I know, you mention this in the footnotes --
>> I'm just afraid that some readers will not read the footnotes, and
>> think "oh, X3D doesn't support this-and-that while glTF does". Just
>> like not all X3D browsers implement the additional components beyond
>> Interchange, but also not all glTF readers implement all features of
>> glTF format, so the *practical* difference between these two formats
>> is more even in my experience.
>>
>> P.S. "Custom shaders" in glTF: work is in progress on
>> https://github.com/KhronosGroup/glTF/tree/master/extensions/Khronos/KHR_technique_webgl 
>>
>> . Indeed, this is not finished (and it's an extension, not part of
>> "core" format spec).
>>
>> Regards,
>> Michalis
>>
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>>
>
>

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