%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2022-01-13 00:10:54
 % @LastEditTime: 2022-01-18 19:53:15
%--------------------------
function seeds = quadtree_nonregular(rho, cpnts, maxx, minx, maxy, miny, maxz, minz, microx, eps)
    % 2. compute faces-center points & rho
    % 3. divide into block with min-size/10
    % while any block>min-size:
    %   divide the into 4
    
    min_size = microx / 2;
    max_size = microx / 1;
    
    %% bounding box and divide into block with max-size
    decomp_info = [];
    for i = minx : max_size : maxx-max_size
        x = [i, i + max_size];

        for j = miny : max_size : maxy-max_size
            y = [j, j + max_size];

            for k = minz : max_size : maxz-max_size
                z = [k, k + max_size];

                [idx, ~] = find(cpnts(:, 1) <= x(2) & cpnts(:, 1) >= x(1) & ...
                                cpnts(:, 2) <= y(2) & cpnts(:, 2) >= y(1) & ...
                                cpnts(:, 3) <= z(2) & cpnts(:, 3) >= z(1));

                if ~isempty(idx)
                    rho_info = mean(rho(idx));
                    decomp_info = [decomp_info; [rho_info, i,j,k, max_size]];
                end
            end
        end
    end

    %% quadtree
    flag = 1;
    while (any(decomp_info(:,1) > eps) || any(decomp_info(:,4) > min_size)) && flag
        flag = 0;
        [r, ~] = find(decomp_info(:,1) > eps);
        
        for ri = 1:length(r)
            di = decomp_info(r(ri), :);
            cur_size = di(end);

            if cur_size > min_size
                flag = 1;
                step = cur_size / 2;
    
                decomp_info(r(ri), 1) = -1;
    
                for i = di(2) : step : di(2) + cur_size - step
                    x = [i, i+step];
    
                    for j = di(3) : step : di(3) + cur_size - step
                        y = [j, j+step];

                        for k = di(4) : step : di(4) + cur_size - step
                            z = [k, k+step];
    
                            [idx, ~] = find(cpnts(:, 1) <= x(2) & cpnts(:, 1) >= x(1) & ...
                                            cpnts(:, 2) <= y(2) & cpnts(:, 2) >= y(1) & ...
                                            cpnts(:, 3) <= z(2) & cpnts(:, 3) >= z(1));
        
                            if ~isempty(idx)
                                rho_info = mean(rho(idx));
                                decomp_info = [decomp_info; [rho_info, i,j,k, step]];
                            end
                        end
                    end
                end
            end
        end
    end

    decomp_info = decomp_info(decomp_info(:,1)>0,:);

    step = decomp_info(:,end)/2;
    seeds = [decomp_info(:,2) + step, decomp_info(:,3) + step, decomp_info(:,4) + step];
%     figure; scatter3(seeds(:,1), seeds(:,2), seeds(:,3), 'filled'); axis equal;
%     view([10 25]);
%     xlabel('x axis');
%     ylabel('y axis');
%     zlabel('z axis');    
end