The horizontal line sounds great. But, doesn't the line have to (should?) wrap around. The value of 359 should be next to the value of 0. The right intercept should equal the left intercept. They don't have to, but isn't that best?
If that is true, can you do the same thing with your x/y curves? 0,0 to 359,359. If you move the 0 intercept (left edge) away from 0,0 to say 10,0, shouldn't 359,359 move also? To say 10,359? I could do some photoshop to illustrate.
I would think the horizontal line would be best, but what if the alternate was far, far easier to program and almost as good.
Excuse my ramblings.