xbr 3d filters not working correctly

[bajolzas]

I've already exposed this issue on the libretro discord some days ago, but I guess I should make it "more official".

My issue is, when using xbr 3d filters they dont appear as they should. This happens for me in both OpenGL/Vulkan and GLSL/slang shaders (cant use cg).

Here's how it looks:

For comparison here is how a simillar named filter correctly looks under pcsxr-pgxp:

At the time @hunterk said that for him these shaders were working correctly under slang, but GLSL versions looked just like mines.