I also thought so, but unfortunately this is not so easy… scalar parameter value 0.5 is 180 degrees but the pivot of clipping mask is the center of the image. So result is incorrect. The pivot of clipping mask should be offset to the left side of my image, not into the center like actually.
Hm, it’s hard for me to give a the perfect advice, because i never really worked with the material editor till now. Can’t you create your own grayscale Mask but only vor 180°? Then it would match your texture :X
I can’t imagine something different from rescallen with UV or directly creating mask and texture alligned to each other.