Unstable FXAA shader result in Anno 5
There is FXAA fragment shader in Anno 5 which with the same input outputs slightly different colors (it's only visible by diffing the output images).
I'm testing on Intel UHD 630 but issue doesn't look to be GPU specific.
I have narrowed down the issue to the algebraic optimizations which say
a * 0.0 = 0.0, in this case:
(('~fmul', a, 0.0), 0.0), and
(('~ffma', 0.0, a, b), b),
I'm not sure how this leads to different color results between several same runs and not in just same but wrong output.
I'll try to look at difference of the NIR during optimizations.