def _arcball(x, y, w, h):
 r = ((w + h) / 2.0)
 (x, y) = (((- ((2.0 * x) - w)) / r), ((- ((2.0 * y) - h)) / r))
 h = np.sqrt(((x * x) + (y * y)))
 return ((0.0, (x / h), (y / h), 0.0) if (h > 1.0) else (0.0, x, y, np.sqrt((1.0 - (h * h)))))

def _arcball ( x , y , w , h ) : r = ( ( w + h ) / 2.0 ) ( x , y ) = ( ( ( - ( ( 2.0 * x ) - w ) ) / r ) , ( ( - ( ( 2.0 * y ) - h ) ) / r ) ) h = np . sqrt ( ( ( x * x ) + ( y * y ) ) ) return ( ( 0.0 , ( x / h ) , ( y / h ) , 0.0 ) if ( h > 1.0 ) else ( 0.0 , x , y , np . sqrt ( ( 1.0 - ( h * h ) ) ) ) )
convert x .