Returns the degree value of the arc tangent of specified X and Y coordinates. The arc tangent is the angle from the X-axis to a line passing through the origin and a point with coordinates X,Y. The returned angle is in degrees, from -180 to 180, excluding -180.
float atan2d(float Y, float X )
X is the X coordinate of the point.
Y is the Y coordinate of the point.
atan2d(1,1)
Returns 45 degrees.