yeah it's definitely a bit weird. I spawn them placing script_origins in radiant with a specific rotation per each one, thus their forward vector is (aprox. for other surfaces) the normal vector to each surface.
I will try later with bullettrace; already did with decal but apparently it doesnt show up in fx ed preview, besides it doesnt let me set the shader framerate.
This is how it looks in non axis-aligned surfaces with the current solution.
how it looks in radiant:
thx