double Map::block::get_delta( double x, double y, double bx, double by ){
        if( slope == 0 ){
            if( y >= by && up )
                return by - y;
            return 0;
        }
        double t =  ( x - bx ) / slope + by + ( slope < 0 ? Global.Block.Size : 0 ) + Global.Block.Size / slope  * segnum;
        if( y >= t )
            return t - y;
        return 0;
    }