Having this binding was redundant, as there's no "normal" texture
sampled when we're doing a channel shuffle, and it caused issues in
Vulkan when the render target or depth buffer the source.
Also fixes the Urban Chaos HLE shader.
Fixes validation errors in GT4, NFS: Carbon, Urban Chaos, probably
others too.
Alpha destination value is wrong so let us try to compensate.
Multiply Cs by (255/128) in shader.
Will work best if Cs is 0.5 or less, if it's higher than 0.5 then the closer to 1 the less accurate it gets.
Ofc it is best to use sw blending but it will help if sw blending is not present/selected for specific draw, will help d3d11 quite more.
Do hw blend for Cd*As, Cd*F, expand the clear color blend method as it is almost the same.
Most helpful for dx11 ofc, for gl/vulkan will help with rendering on lower
levels of blending without needing a barrier.
Clamp the alpha(As/Af) to 1 in the shader, it is already clamped to 1 in hw blend unit.
It should allow to better render the effects, still not fully accurate but it's closer to what we want.
Hopefully it helps D3D11 more.
Connor McLaughlin