[x3d-public] wondering about glTF and Draco relationship

[Leonard Daly]

Below is my response reviewed by 3D Formats WG. Don's questions were 
pulled out and included here in green.


 > Question about Draco: thought it was usable as a preprocessor for 
glTF files that could produce .glb files, but is that incorrect?

Draco is compatible with glTF. There is an extension (Announcement: 
https://www.khronos.org/news/press/khronos-announces-gltf-geometry-compression-extension-google-draco; 
Specification: 
https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Khronos/KHR_draco_mesh_compression/README.md) 
that is required for this (Draco) to work.


 > If Draco is compatible with glTF do we need to mention it (as an 
optional perhaps) in X3D4?
 > If Draco-compressed files are not compatible with glTF files, what is 
the relationship?  What are their intentions?

Depends on what level of glTF support Web3D wishes to impose on X3D. 
Draco support is an extension to the core glTF V2.0 specification. Draco 
is fundamentally a memory-based operation. The GitHub package from 
Google includes encoders and decoders. The glTF extension handles the 
Draco Bitstream (https://google.github.io/draco/spec/)


 > Near-term impact: do we need to add any comments in X3D4 submission 
to ISO ballot (deadline 5 May)?

That is a Web3D issue.


 > Long-term impact: can we encourage use of Draco-processed loading of 
glTF models, or will we need to wait until revisiting X3D Compressed 
Binary Encoding?

The Asset Creation Guidelines 
(https://github.com/KhronosGroup/3DC-Asset-Creation/blob/main/asset-creation-guidelines/RealtimeAssetCreationGuidelines.md*) 
*from the 3D Commerce WG of Khronos recommends using Draco compression 
for geometry and use of KTX images (https://www.khronos.org/ktx/) for 
image transmission/GPU use. It is up to Web3D Consortium to determine 
how X3D wishes to use them.


Leonard Daly



On 4/22/2021 8:23 AM, Don Brutzman wrote:
> Hello Web3D-Khronos Liaison Experts!  Here are some public questions 
> for you, originating in our CAD Design Printing Scanning and X3D 
> Working Groups.
>
> Question about Draco: thought it was usable as a preprocessor for glTF 
> files that could produce .glb files, but is that incorrect?
>
> * https://google.github.io/draco
>
> "Draco is an open-source library for compressing and decompressing 3D 
> geometric meshes and point clouds. It is intended to improve the 
> storage and transmission of 3D graphics."
>
> If Draco is compatible with glTF do we need to mention it (as an 
> optional perhaps) in X3D4?
>
> If Draco-compressed files are not compatible with glTF files, what is 
> the relationship?  What are their intentions?
>
> Near-term impact: do we need to add any comments in X3D4 submission to 
> ISO ballot (deadline 5 May)?
>
> Long-term impact: can we encourage use of Draco-processed loading of 
> glTF models, or will we need to wait until revisiting X3D Compressed 
> Binary Encoding?
>
> Thanks in advance for all inquiry and insight.
>
> all the best, Don


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