public Transform center;
public Transform menuPart;

if(menuActive)
{
	Vector2 distance = center.position - Input.mousePosition;
	float tempAngle = Mathf.Atan2(distance.y, distance.x) * Mathf.Rad2Deg;
	tempAngle += 180f;

	for (int i = 0; i < 360; i +=45)
	{
		if(tempAngle >= i && tempAngle < i +45)
		{
			menuPart.eulerAngles = new Vector3(0,0,i);
		}
	}
}