Fix WebGL mode for Adreno GPUs

[TotalKrill]

Objective

• This fixes a crash when loading shaders, when running an Adreno GPU and using WebGL mode.
• Fixes Fog crashes on certain mobile devices in WASM #8506
• Fixes WASM WebGL examples crash "wgpu error: Validation Error" #8047

Solution

• The shader pbr_functions.wgsl, will fail in apply_fog function, trying to access values that are null on Adreno chipsets using WebGL, these devices are commonly found in android handheld devices.

[alice-i-cecile]

I can't verify this myself, but the comments are good and the fix is reasonable.

[superdump]

Hmm, is this the case for all WebGL2? Or just with some Adreno GPU drivers?

[TotalKrill]

Its actually only the case for Adreno GPU drivers, but I am not sure how to address that.

[Elabajaba]

I don't think it's possible if we're using a const here, since you have to query the gpu driver at runtime.

edit: Also, is this for all Adreno GPUs, or only certain ones? Do you know if it's an issue on just Android, or does it also impact Linux?

edit2: I should've read the linked issues first...

[mockersf]

so the question is, do we want to reduce functionality for all webgl2 app for a few android devices?

[Elabajaba]

so the question is, do we want to reduce functionality for all webgl2 app for a few android devices?

If we make this not a const, it's possible to detect the driver at runtime using https://github.com/gfx-rs/wgpu/blob/2571af9557eeba59f00f69649ae6bcd9d5a62392/wgpu-types/src/lib.rs#L1303

[TotalKrill]

so the question is, do we want to reduce functionality for all webgl2 app for a few android devices?

Yeah, I agree, its not the ideal solution. And getting a feature to start tweaking rendering paths depending on which adaptor is detected, will probably be the best solution.

But then again, this is at least a third of all android devices (Adreno marketshare is approx 33% from what I can tell), not really only a few. And we are talking about a hard crash on approx 1/3 of android devices, that was not there before 10.0 vs having 9 extra directional lights available for webgl targets.

I still think that speaks in favor of this. Even if not ideal. And it will not crash WebGL targets that use more directional lights.

[TotalKrill]

In addition to this, I also do not think that more directional lights works as intended on WebGL regardless, from what I can tell, shadows does not seem to work at least on my computer.

[cart]

If we make this not a const, it's possible to detect the driver at runtime using https://github.com/gfx-rs/wgpu/blob/2571af9557eeba59f00f69649ae6bcd9d5a62392/wgpu-types/src/lib.rs#L1303

I briefly poked around with this. Making it non-const is non-trivial and will require a bit of elbow grease.

I do think thats the best long-term strategy though. We should investigate it. I created #8992 to track that.

I just resolved merge conflicts.