nl_tokens: obtains from http : // theory . stanford . edu / ~amitp / GameProgramming / Heuristics . html
pl_tokens: protected double getDiagonalHeuristicCost ( double x , double y , double gx , double gy , double dFactor ) { double dx = Math . abs ( x - gx ) ; double dy = Math . abs ( y - gy ) ; double h_diagonal = Math . <mask> ( dx , dy ) ; double h_straight = dx + dy ; return ( dFactor * 2 ) * h_diagonal + dFactor * ( h_straight - 2 * h_diagonal ) ; }