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UE5 Nanite in WebGPU

github.com

1–10 of 117 posts

Re: UE5 Nanite in WebGPU

#2
It's cool that it kind of works, but they had to make some nasty compromises to get around WebGPUs lack of 64 bit atomics. Hopefully that will be added as an optional extension at some point, hardware support is almost ubiquitous on desktop-class hardware at least (AMD and Nvidia have had it forever but Apple has only had it since the M3).

Re: UE5 Nanite in WebGPU

#3
post #2

It's cool that it kind of works, but they had to make some nasty compromises to get around WebGPUs lack of 64 bit atomics. Hopefully that will be added as an optional extension at some point, hardware support is almost ubiquitous on desktop-class hardware at least (AMD and Nvidia have had it forever but Apple has only had it since the M3).

What is the use case for atomics in the rasterizer? I can’t figure out what the atomic operations do inside the rendering pipeline. I looked at the GitHub, but couldn’t find the place the atomic were hoped for.

Re: UE5 Nanite in WebGPU

#5
post #2

It's cool that it kind of works, but they had to make some nasty compromises to get around WebGPUs lack of 64 bit atomics. Hopefully that will be added as an optional extension at some point, hardware support is almost ubiquitous on desktop-class hardware at least (AMD and Nvidia have had it forever but Apple has only had it since the M3).

What is the use case for atomics in the rasterizer? I can’t figure out what the atomic operations do inside the rendering pipeline. I looked at the GitHub, but couldn’t find the place the atomic were hoped for.

Pack Z and 32-bit color together into a 64-bit integer, then do an atomic min (or max with reversed Z) to effectively do a Z-query and a write really, really fast.

Re: UE5 Nanite in WebGPU

#8
post #2

It's cool that it kind of works, but they had to make some nasty compromises to get around WebGPUs lack of 64 bit atomics. Hopefully that will be added as an optional extension at some point, hardware support is almost ubiquitous on desktop-class hardware at least (AMD and Nvidia have had it forever but Apple has only had it since the M3).

What is the use case for atomics in the rasterizer? I can’t figure out what the atomic operations do inside the rendering pipeline. I looked at the GitHub, but couldn’t find the place the atomic were hoped for.

Visibility buffer needing atomics is noted briefly in the long README. Link to discussion detailing it: https://github.com/Scthe/nanite-webgpu/issues/1

Re: UE5 Nanite in WebGPU

#9
It says my iPhone 12 Pro Max doesn’t have WebGPU, but I enabled it in experimental features and another website[1] with WebGPU demos now works. Has anyone gotten this working on iPhone? Would be nice if the web app gave more info on what failed.

[1] https://webgpu.github.io/webgpu-samples/?sample=texturedCube

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