good iq puzzle (not scuffed like my pet's)

[bluerose]

ok so, two empty spots, with f3 being an anomaly (only black line) imply the puzzle is to be solved mostly horizontally.
blue and red lines make a black line somehow.
likely elements to solve this are angles, or rotation.
perhaps an addition or rotation of lines does occur vertically, which is how you would extrapolate data to solve it horizontally ...

am i on the right track?