normalizeAngle360 function
Normalizes degrees into the range [0, 360).
Negative inputs wrap around, so -90 becomes 270.
Example:
normalizeAngle360(450); // 90.0
normalizeAngle360(-90); // 270.0
Implementation
double normalizeAngle360(double degrees) {
double d = degrees % 360;
if (d < 0) d += 360;
return d;
}