%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2021-11-01 15:24:36
 % @LastEditTime: 2022-01-03 21:55:46

 % c_vedges: the edges of each voronoi cell, [x1,y1,x2,y2] * n-rows
 % c_polys: the nodes of each voronoi cell, [x1,y1,x2,y2] * n-rows
 % c_nodes
 % nfaces_local: nfaces in each cvt
%--------------------------
% read file version
function [c_nodes, c_faces, c_vedges, c_polys] = generate_mesh_fromCVT(ncvt, path0, delta)

    cc_nodes  = cell(ncvt, 1);
    c_faces  = cell(ncvt, 1);
    c_vedges = cell(ncvt, 1);
    c_polys  = cell(ncvt, 1);

    polyvec = [];
    figure;
    for i = 40 : ncvt
        [vor_edges, pgon] = read_cvt(i-1, path0);
        c_vedges{i} = vor_edges;
        c_polys{i}   = pgon; % [n,2]
        polyvec = [polyvec; polyshape(pgon)];

        [~, ~, tri_nodes, tri_faces] = read_cdt(i-1, path0, delta);
        c_nodes{i} = tri_nodes;
        c_faces{i} = tri_faces;        
        
        plot(polyshape(pgon),'FaceColor','white','EdgeColor','k','LineWidth', 2, 'FaceAlpha',0); hold on;
    end
    axis equal; axis off
%     figure; h = plot(polyvec,'FaceColor','white','EdgeColor','black');
%     h.LineWidth = 1.5;
end

function [pnts_num, faces_num, nodes, faces] = read_cdt(i, path0, delta)
    datapath = [path0+'cdt'+num2str(i)]; 
    fileID = fopen(datapath, 'r');
    info = fscanf(fileID, '%f');

    pnts_num = info(1);
    faces_num = info(2); 
    nodes = reshape(info(3 : 3+pnts_num*2-1), 2, [])'; % all nodes coodinates of cdt
%     faces = reshape(info(3+pnts_num*2 : end), 3, [])'; % faces of cdt, formed of node-nidx
%     faces = faces + 1; % faces begins with 0

    fclose(fileID);

    dt = delaunayTriangulation(nodes);      
%     figure; clf; triplot(dt,'Color','black');
    faces = dt.ConnectivityList;    
    
%     if i == 39
        triplot(dt,'LineStyle','--','Color','k','LineWidth', 1); hold on;
%     end

    faces = checkValid_trimesh(nodes, faces, delta);
    faces_num = size(faces, 1);
end

function [edges, pgon] = read_cvt(i, path0)
    datapath = [path0+'vcell'+num2str(i)]; 
    fileID = fopen(datapath, 'r');
    info = fscanf(fileID, '%f');

    pnts_num = info(1);
    edges = reshape(info(2 : end), 4, [])'; % [x1,y1,x2,y2]
    
    fclose(fileID);

    pgon = edges(:, 1:2);
end

% reorder the edges to [end to end]
function new_edges = reorder_edges(edges)

    new_edges = edges;
    edges(1,:) = [];
    
    for i = 1 : size(new_edges, 1)-1
        nj = new_edges(i, 2);
        
        [r,c] = find(edges==nj);
        if c == 2
            new_edges(i+1, :) = fliplr(edges(r,:));
        else
            new_edges(i+1, :) = edges(r,:);
        end
        edges(r,:) = [];
    end
end

function [nodes_new, faces_new] = remove_repeated_nodes(nodes, faces)
    % remove the repeated nodes
    [nodes_new, ia, ic] = unique(nodes, 'rows'); % new=nodes(ia), nodes=new(ic)

    old_order = [1 : nidx]';
    new_order = ic;
    faces_new = changem(faces,new_order,old_order);
    % faces = faces_new;
    % nodes = nodes_new;
end