%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2022-01-06 15:33:25
 % @LastEditTime: 2022-01-27 11:29:02

 % specifically for those repeated edges with opposite directions
%--------------------------
function [edges1] = unique_edges(edges0)

    % remove repeated edges with opposite direction
    dir1 = edges0(:, 4:6) - edges0(:, 1:3);

    IDX = 1:size(dir1, 1);
    negIDX = IDX(abs(dir1(:, 1)) > 1e-5 & dir1(:,1) < 0);

    borderIDX1 = find(abs(dir1(:, 1)) < 1e-5 & abs(dir1(:, 2)) > 1e-5 & dir1(:, 2) < 0);
    borderIDX2 = find(abs(dir1(:, 1)) < 1e-5 & abs(dir1(:, 2)) < 1e-5 &...
                          dir1(:, 3) < 0);

    negIDX = [negIDX(:); borderIDX1(:); borderIDX2(:)]; 

    posIDX = setdiff(IDX, negIDX);

    edges2(negIDX, :) = [edges0(negIDX, 4:6), edges0(negIDX, 1:3)];
    edges2(posIDX, :) = edges0(posIDX, :);

%     e0(:,1) = mean(edges0(:,[1,4]), 2);
%     e0(:,2) = mean(edges0(:,[2,5]), 2);
%     e0(:,3) = mean(edges0(:,[3,6]), 2);
    [~, ia, ~] = uniquetol(edges2, 'ByRows', true ); 
%     [~, ia, ~] = unique(edges2, 'rows'); 
% 
    edges1 = edges0(ia,:);
end