To do this, I had to decouple framebuffer fetch from shader blending. We need to be able to access framebuffer fetch input when using shader logic ops.
Specifically, when using Manual Texture Sampling, if textures sizes don't match the size the game specifies, things previously broke. That can happen with custom textures, and also with scaled EFB copies at non-native IRs. It breaks most obviously by not scaling the texture coordinates (so only part of the texture shows up), but the hardware wrapping functionality also assumes texture sizes are a power of 2 (or else it will behave weirdly in a way that matches how hardware behaves weirdly). The fix is to provide alternative texture wrapping logic when custom texture sizes are possible.
Note that both GLSL and HLSL provide a fwidth (fragment width) function defined as `fwidth(p) = abs(dFdx(p)) + abs(dFdy(p))`. However, it's easy enough to implement this ourselves (and it makes the code a bit more obvious).
The benefit to exposing this over the raw BP state is that adjustments Dolphin makes, such as LOD biases from arbitrary mipmap detection, will work properly.
SPDX standardizes how source code conveys its copyright and licensing
information. See https://spdx.github.io/spdx-spec/1-rationale/ . SPDX
tags are adopted in many large projects, including things like the Linux
kernel.
This fixes bounding box shaders failing to compile under Vulkan, due to
differences between GLSL and HLSL in the return value of vector
comparisons and what types these functions accept. I included all() for
the sake of completeness.