Bug: PBR shader incorrectly gets lit by lights when viewmodel is drawn

[Equalizer5118]

Describe the bug

The PBR shader does not light correctly when the ViewModel is drawn, producing vastly incorrect lighting. This effect is greatly amplified when using the light from the skybox when CSM does not exist.

It seems to be tied to the lighting of the ViewModel for some reason, as the color fading effect on the ViewModel also seems to affect the PBR materials:
https://github.com/StrataSource/Engine/assets/113145248/22c7c729-0a19-42ee-ba84-988a0cb6d4f2

Here are some example screenshots:

To Reproduce

1. Open given map
2. Walk into the sunlight
3. Observe lighting difference
4. Remove the cascade light ( ent_remove env_cascade_light )
5. Walk into sunlight
6. Observe bug

Then repeat this with the ViewModel disabled

Issue Map

pbr_light_test.zip

Expected Behavior

lighting should remain consistent when viewmodel interacts with

Operating System

Tested on Windows 11

[Equalizer5118]

Side note: There are a couple light_spot entities. That is intentional, I was testing to see if lighting bug works on those. For some reason, it does not

[MyGamepedia]

I highly recommend to share here your .VMT of your texture, there may be a problem with it. I came across very similar situation when I tried to use VertexLitGeneric for brushes.

[Equalizer5118]

isnt vertexlitgeneric only supposed to be used with models?

[MyGamepedia]

no but your issue show similar results, I have an idea that you maybe just have problem in your vmt file.

[Equalizer5118]

"PBR"
{
	$basetexture               "PBR/metal/wall_corrugated_white_main_basecolor"
	$bumpmap                   "PBR/metal/wall_corrugated_white_main_bump"
	$mraotexture               "PBR/metal/wall_corrugated_white_main_mrao"

	$envmap                    "env_cubemap"
	$normalmapalphaenvmapmask  1

	$parallax 1
	$parallaxcenter .73
	$parallaxdepth .13

	%NoPortal 1
}

Created straight from PBR-2-Source, with only the parallax params noportal flag being added

[Equalizer5118]

metal.zip

[JJL772]

Fixed in staging