docs: private boolean check( int x , int y , boolean match ) {
  
  		if( intensity.isInBounds(x,y)  ) {
  			int index = intensity.getIndex(x,y);
  			if( intensity.data[index] >= lower ) {
  				intensity.data[index] = MARK_TRAVERSED;
  				output.unsafe_set(x,y,1);
  
  				if( match ) {
  					open.grow().set(x, y);
  				} else {
  					active.set(x,y);
  				}
  				return true;
  			}
  		}
  		return false;
  	}