WebGPURenderer: Support BatchedMesh.

[RenaudRohlinger]

Related issue: #22376

Description

This PR adds BatchMesh support to the WebGPURenderer on both backends. At this moment the WebGPU doesn't use any multi draw, let's add it once multiDrawIndirect is available (more info gpuweb/gpuweb#2315).

On my MacBook Pro M1 Max:
WebGPU: 120fps+, 4ms CPU average, 5GPU
WebGL: 65 fps, 7.6ms CPU, 5GPU

Example:
https://raw.githack.com/renaudrohlinger/three.js/utsubo/feat/webgpu-batch/examples/webgpu_mesh_batch.html

Also fixed some issue regarding timestamps getting reset when computeAsync wasn't being used.
Finally, I refactored the WebGLBackend with WebGLBufferRenderer.

This contribution is funded by Utsubo

[vegarringdal]

Nice

Tried the sample link, dont see much difference between webgpu/webgl.
Maybe I did something wrong ?
Added som images, ran both at the same time.

AMD RX5700XT
AMD Ryzen 7 3700X 8-Core Processor 3.59 GHz
Windows 11

Edge

Chrome

[RenaudRohlinger]

Which reminds me that maybe we should add the GPURenderBundle and consider the PR of @aardgoose (#26983). This PR will benefit a lot from it.

Related:
#26876
#26983

/cc @sunag

[RenaudRohlinger]

@vegarringdal I guess 20k instances doesn't seems enough to see noticeable differences. My numbers comes from a sample of 40k instances. Also I don't want to burn the CPUs of developers so I guess 20k is a good limit.

[vegarringdal]

@RenaudRohlinger

K, would nice to be able can compare performance with minimal work.
So if it will be an official sample, then it would prefer to be able to try and kill my cpu/gpu 😄

But anyways, thanks for helping making the webgpu part more complete 👍
Will be fun to see what's possible with webgpu/threejs in the future.

[mrdoob]

Something broke this feature...

https://threejs.org/examples/?q=batch#webgpu_mesh_batch

If I set count to 20000 nothing changes visually:

Seems like only the WebGPU bakend broke though...

[RenaudRohlinger]

Will check! Probably just an issue with the example or the BatchNode not supporting dynamic update yet.