%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2021-11-01 16:00:36
 % @LastEditTime: 2022-01-12 20:51:13

 % NOTE: the bounding box is [minx, maxx] & [miny, maxy]
%--------------------------
function [freedofs, fixeddofs, fext, alldofs] = design_domain_nonregular(nodes, ...
    opt, vF, minx, maxx, miny, maxy)

    nodes(:,3) = 1 : size(nodes,1);

    switch opt
    case 'Lshape'
        % fixed: (:, maxy)
        [ix, ~] = find(abs(nodes(:,2)-maxy) < 1e-5);
        fixednid = nodes(ix, 3);
        fixeddofs = [2*fixednid(:), 2*fixednid(:)-1]';

        % load: (maxx, 0) on y
        [ix, ~] = find(abs(nodes(:, 1)-maxx) < 1e-5);
        nodes1 = nodes(ix, :);
        [iy, ~] = find(abs(nodes1(:, 2)) < 1e-5);
        loadnid = nodes1(iy, 3);
        loaddofs = 2 * loadnid;

        vF = -vF;

    case 'cantilever'
        % fixed: (minx, :)
        [ix, ~] = find(abs(nodes(:,1)-minx) < 1e-5);
        fixednid = nodes(ix, 3);
        fixeddofs = [2*fixednid(:), 2*fixednid(:)-1]';

        % load: (maxx, miny) on y
        [ix, ~] = find(abs(nodes(:, 1)-maxx) < 1e-5);
        nodes1 = nodes(ix, :);
        [iy, ~] = find(abs(nodes1(:, 2)-miny) < 1e-5);
        loadnid = nodes1(iy, 3);
        loaddofs = 2 * loadnid;

        vF = -vF;

    case 'michell'
        % fixed: (minx, :)
        [ix, ~] = find(abs(nodes(:,1)-minx) < 1e-5);
        fixednid = nodes(ix, 3);
        fixeddofs = [2*fixednid(:), 2*fixednid(:)-1]';

        % load: (maxx, (maxy-miny)/2) on y
        [ix, ~] = find(abs(nodes(:, 1)-maxx) < 1e-5);
        nodes1 = nodes(ix, :);
        [iy, ~] = find(abs(nodes1(:, 2)-(maxy-miny)/2) < 1e-5);
        loadnid = nodes1(iy, 3);
        loaddofs = 2 * loadnid;
        
        vF = [-vF,vF]*sqrt(2)/2;

    end
%     figure; scatter(nodes(:,1), nodes(:,2)); hold on;
%     scatter(nodes(fixednid,1), nodes(fixednid,2), 'filled', 'r'); hold on;
%     scatter(nodes(loadnid,1), nodes(loadnid,2), 'filled', 'k');

    alldofs = size(nodes, 1) * 2;
    fixeddofs = fixeddofs(:);
    freedofs  = setdiff(1:alldofs, fixeddofs);
    fext = sparse(loaddofs(:), 1, vF(:), alldofs, 1);
end