%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2021-12-03 19:58:59
 % @LastEditTime: 2021-12-06 16:53:59
%--------------------------
function [valid_faces] = checkValid_trimesh(nodes, faces, delta)
    x = nodes(:, 1); % [n, 1]
    x = x(faces);    % [m, 3]
    y = nodes(:, 2); % [n, 1]
    y = y(faces);    % [m, 3]
    area = 0.5 * ((x(:,1).* y(:,2) - x(:,2).*y(:,1)) + ...
                (x(:,2).* y(:,3) - x(:,3).*y(:,2)) + ...
                (x(:,3).* y(:,1) - x(:,1).*y(:,3)));
    [idx, ~] = find(abs(area) < delta);

    nfaces = size(faces, 1);
    vaild_idx = setdiff(1:nfaces, idx);
    valid_faces = faces(vaild_idx, :);
%     nonvalid_faces = faces(idx, :);

%     valid_nodes = nodes;
%     test = unique(valid_faces(:));
%     figure; trimesh(valid_faces,nodes(:,1),nodes(:,2));
end