rsx/gl/vk/dx12: Add emulated texture fetch for depth read

[kd-11]

#1949

In theory, this allows reading a depth texture into RGBA8 without losing precision. Directly storing depth values into 8-bit textures loses some precision that is hopefully fixed by this.

[mention-bot]

@kd-11, thanks for your PR! By analyzing the annotation information on this pull request, we identified @vlj, @raven02 and @Nekotekina to be potential reviewers

[kd-11]

@SakataGintokiYT Please check if it fixes depth problems with naruto. The bad shadows are due to a different issue since they appear earlier on in the draw call, before this particular issue starts. I've analyzed traces from 3 naruto games and they all seem to use the same pattern.

[SakataGintokiYT]

@kd-11
Depth works well

[VK]

[DX12]

[GL]

E {rsx::thread} RSX: Failed to compile vertex shader: 0(61) : error C1020: invalid operands to "/"
0(61) : error C1020: invalid operands to "/"
0(61) : error C1020: invalid operands to "/"

E {rsx::thread} RSX: Failed to compile shader: 0(59) : error C1020: invalid operands to "/"
0(59) : error C1020: invalid operands to "/"
0(59) : error C1020: invalid operands to "/"

F {rsx::thread} class gl::glsl::link_exception thrown: linkage failed: 'Vertex info
-----------
0(61) : error C1020: invalid operands to "/"
0(61) : error C1020: invalid operands to "/"
0(61) : error C1020: invalid operands to "/"
(0) : error C2003: incompatible options for link

Fragment info
-------------
0(59) : error C1020: invalid operands to "/"
0(59) : error C1020: invalid operands to "/"
0(59) : error C1020: invalid operands to "/"
(0) : error C2003: incompatible options for link
'

Shaderlog

[kd-11]

Seems like nvidia compiler doesnt like automatic cast from unsigned int to float.

[kd-11]

Should be fixed now

[SakataGintokiYT]

@kd-11
Now works on GL.

It's good for merge.

[raven02]

@kd-11 .Let me know if it is okay to merge.

[kd-11]

Should be good to merge if there are no regressions reported.