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Comment by randyrand | Hacker News Reader

My favorite format for this is Gltf. The spec is very concise, and powerful.

https://github.com/KhronosGroup/glTF/tree/master/specificati...

And most importantly for a runtime format, glTF is fast and easy to load. It's specifically designed to mirror the capabilities of real-time 3D APIs and allow mesh data to be memcpy'd directly onto the GPU with zero processing at load-time. On the other hand USD/USDZ doesn't even attempt to be GPU-friendly, given it was designed as an exchange format for production.

Although USD's native binary format compresses integer topology data, mesh (and curve) point, normal, and uv data is laid out in arrays that can be directly uploaded to a gpu from the file system with zero copies or processing.

It is true that there are several more software layers in USD between file-open and mesh-data-extraction, but to the earlier "forward looking" comment, what you get for that are built on features for allowing clients to select variations with smart/sparse updating, and serious scalability features, for larger scenes. These are all features that have been added since USD's release, and there is still quite a lot of development underway.

No knocks on glTf, which does a great job at what it's designed for. But maybe Apple is looking at a different future?

I found the layer and streaming features interesting. It seems to me like that's the big win over gltf. Correct me if I'm wrong, but it seems like USD might support things like streaming LODs or even tiling long term.

Also supported in products already by Facebook, Google, and even Microsoft. Really disappointed that Apple went their own way on this.

Apple didn't go their own way one this - they teamed up with the people who know this better than anyone, from Pixar to Epic.

No, they made a minor change to an existing Pixar file format. Pixar who they already had a very cozy relationship with. The whole industry was standardizing onto glTF and Apple couldn't let that stand.

Your assumptions underscore your bias. Perhaps they have bigger dreams then the rest of industry.

Apple stands out from the rest of those industry players by historically having much longer range architectural vision. They have also been investing heavily in their devices for many years to support that vision. The processing power of the typical iPhone outruns average competitor by multiples.

Epic? As far as I can tell, Unreal Engine supports glTF import and does not support USDZ.

Which makes sense, because this is what glTF was designed for.

https://forums.unrealengine.com/development-discussion/conte...

Posting that Epic can import more than one file format does not prove me wrong.

Thankfully, some quotes from Epic Directors can prove me right....

https://uploadvr.com/epic-games-unreal-engine-april/

To quotes the Technical Director from Epic:

“We will increasingly use USD here. Hopefully, we will keep working with Pixar to make it awesome for every use case we can imagine. ”

And,

“The cool thing here is that we don’t need any other separate tools to go from USD to what you’d see on screen with this demo”

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