(svn r12870) -Codechange: remove some magic numbers from u.ship.state handling

src/direction_func.h

@@ -167,6 +167,22 @@ static inline DiagDirection AxisToDiagDir(Axis a)
 	return (DiagDirection)(2 - a);
 }
 
+/**
+ * Converts an Axis to a Direction
+ *
+ * This function returns the Direction which
+ * belongs to the axis. As 2 directions are mapped to an axis
+ * this function returns the one which points to south,
+ * either south-west (on X axis) or south-east (on Y axis)
+ *
+ * @param a The axis
+ * @return The direction pointed to south
+ */
+static inline Direction AxisToDirection(Axis a)
+{
+	return (Direction)(5 - 2 * a);
+}
+
 /**
  * Convert an axis and a flag for north/south into a DiagDirection
  * @param xy axis to convert