Vertex lighting not quite right in Ridge Racer, other games

[hrydgard]

As can be seen in some screenshots in #16083, we're a bit off.

One idea is that specular might be using some approximation for the power function, for example.

Quoth @unknownbrackets :

Some interesting things about this frame dump:

The correct rendering on the PSP has better shading:

Compared to the current rendering in Vulkan (I'm not sure about the top left, it's only happening in headless):

Also as you can see from the PSP frame dump, somehow the CLUT was not captured. It knows it's a target, but somehow it's not getting rendered properly (even on a PSP), probably some issue with the dump machinery... well, forcing it to use the CLUT from the framedump gives this:

Software also gets the lighting wrong, outside the weird flickering:

The texture filtering looks more accurate, which is nice, but the lighting is just as wrong (some in the background as well.) Of course, there's also the weird flickering... gotta see what's going on there.

More in https://github.com/hrydgard/ppsspp/issues/16083#issuecomment-1256940001 and https://github.com/hrydgard/ppsspp/issues/16083#issuecomment-1257129459 .