%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2021-12-13 20:05:32
 % @LastEditTime: 2021-12-22 14:24:48

 % rangesearch, for filter
%--------------------------
function [neighbors, center_nodes] = neighbor_faces(nodes_cell, faces_cell, r)

    ncvt = size(nodes_cell, 1);
    neighbors = cell(ncvt, 1);
    center_nodes = cell(ncvt, 1);
    
    for ele = 1:ncvt
        nodes = nodes_cell{ele};
        faces = faces_cell{ele};

        x = nodes(:, 1); 
        y = nodes(:, 2);
        x = x(faces); % [m,3]
        y = y(faces);
        cx = mean(x, 2);
        cy = mean(y, 2);

        Mdl = KDTreeSearcher([cx, cy]);
        neighbors{ele} = rangesearch(Mdl, [cx, cy], r);                         

%         tmp = neighbors{ele}{1};
%         r1 = [cx(tmp), cy(tmp)] - repmat([cx(1), cy(1)], length(tmp), 1);
%         vecnorm(r1)

        center_nodes{ele} = [cx, cy];
    end
end