Split screen on landscape mode multiple issues

[SPiNNiX]

Hello

I have multiple issues with the cocktail table shader. Please see this pictures: https://imgur.com/a/irLFe5w

I used this shader to split the screen: https://raw.githubusercontent.com/hizzlekizzle/glsl-shaders/master/misc/cocktail-cabinet.glsl

I have these issues:

As the screen has to display the video in a widescreen manner because the players sit at the top and bottom edge of the screen (and not left and right), I need to make either some changes to the shader (where I don't know how) or rotate the screen which leads to the problem that I have custom_viewport settings in my retroarch.cfg

aspect_ratio_index = 23
custom_viewport_width = 1100
custom_viewport_height = 1080
custom_viewport_x = 0
custom_viewport_y = 418

Next the screens are not placed right, but this is not a big issue as I can change the params for each emulator which I will do after fixing the other problems.

The last problem is that the screens are mirrored while in the screenshots of other users everything seems right.

Help is appreciated a lot, if you need cfg files or logs, tell me, but as the cabinet is not in my house, it takes me a while to provide these.