% get the connectClusterIDX for clusterIDX
% K * 4 * (K-1): 
% For K clusters:
%   for 4/8 dirs:
%       if connect to the other (K-1) clusters
function connClusterIDX = connectClusterIDX(connectEle, clusterIDX, K, optNeighbor)

    connClusterIDX = zeros(K, optNeighbor, K-1);

    eleNums = size(connectEle,1);
    for i = 1:eleNums        
        ci = clusterIDX(i,1);

        conn = connectEle(i,:);
        for j = 1:optNeighbor
            if conn(j)>0
                cj = clusterIDX(conn(j),1);                
                connClusterIDX(ci,j,cj) = 1;
            end
        end
    end
end