That's intriguing.
What sort of variable is d? I think when d+90 = 255, then it wraps to d+90 = 0 sent into the function, giving you sin 0 again.
I see mister Boriel got to the same answer while I was looking and typing
What sort of variable is d? I think when d+90 = 255, then it wraps to d+90 = 0 sent into the function, giving you sin 0 again.
I see mister Boriel got to the same answer while I was looking and typing