code: public static final Direction getQuadrant(final double cx, final double cy, final double x0, final double y0)
      {
          if ((x0 > cx) && (y0 < cy))
          {
              return Direction.NORTH_EAST;
          }
          if ((x0 > cx) && (y0 >= cy))
          {
              return Direction.SOUTH_EAST;
          }
          if ((x0 <= cx) && (y0 >= cy))
          {
              return Direction.SOUTH_WEST;
          }
          // if( x0 <= c.getX() && y0 < c.getY() )
          return Direction.NORTH_WEST;
      }
docs: Returns the NESW quadrant the point is in.  The delta from the center
  NE x > 0, y < 0
  SE x > 0, y >= 0
  SW x <= 0, y >= 0
  NW x <= 0, y < 0
  
  @param cx
  @param cy*
  @param x0
  @param y0
  @return