Comment by tubs

As the other posters have shown it’s not that hard.

Most graphics specs will explicitly say how tie break rules work.

The key is to work in fixed point (16.8 or even 16.4 if you’re feeling spicy). It’s not “trivial” but in general you write it and it’s done. It’s not something you have to go back to over and over for weird bugs.

Wide lines are a more fun case…