%--------------------------
 % @Author: Jingqiao Hu
 % @Date: 2022-01-08 22:27:37
 % @LastEditTime: 2022-01-29 15:30:40

 % c_interPolyMMC: the intersected polygon for each mmc
 % c_interPolySeed: the intersected polygon for each seed
 % each mmc is simplified as a segment
%--------------------------
function [c_interPolySeed] = do_intersection(vedges, c_polyMesh, c_nnbEdgeIDX, seeds)

    ncvt  = size(c_polyMesh, 1);
    npnts = size(seeds, 1);
    
    % computer the intersected-idx of each polytope-cell for each MMC
    c_interPolyMMC = cell(ncvt, 1);
    for i = 1 : size(vedges, 1)

        p1 = vedges(i,1:3);
        p2 = vedges(i,4:6);

        interP = zeros(ncvt, 2);
        interP(:,2) = 1:ncvt;

        parfor j = 1 : ncvt
            pnts = c_polyMesh{j};
            intersect = TriangleRayIntersection(p1, p2, pnts(:, 1:3), pnts(:,4:6), pnts(:,7:9), ...
                'lineType' , 'segment', 'border', 'inclusive' );

            if sum(intersect) > 0
                interP(j, 1) = 1;
            end
        end
        c_interPolyMMC{i} = interP(interP(:,1) > 0, 2);

%         % test
%         figure(1); clf 
%         x = vedges(:,[1,4]);
%         y = vedges(:,[2,5]);
%         z = vedges(:,[3,6]);
%         plot3(x',y',z','LineWidth',1, 'Color','k'); hold on;  
%         segs = vedges(i, :);
%         x = segs(:,[1,4]);
%         y = segs(:,[2,5]);
%         z = segs(:,[3,6]);
%         plot3(x',y',z','LineWidth',2); hold on; axis equal;
%         idx = c_interPolyMMC{i};
%         for j = 1:length(idx)
%             verts = c_polyMesh{idx(j)};
%             scatter3( verts(:,1), verts(:,2), verts(:,3), 'filled'); hold on;
%             scatter3( verts(:,4), verts(:,5), verts(:,6), 'filled'); hold on;
%             scatter3( verts(:,7), verts(:,8), verts(:,9), 'filled'); hold on;
%         end
        
    end

    % compute the intersected-idx of each polygon-cell for each seed
    c_interPolySeed = cell(npnts, 1);
    parfor i = 1 : npnts
        MMCs_id = c_nnbEdgeIDX{i}; % the corresponding idx in MMCs_poly for each seed
        interP = [];

        for j = 1 : numel(MMCs_id)
            mj     = MMCs_id(j);         % this MMCs_poly id
            pgonID = c_interPolyMMC{mj}; % the intersected mesh-polygon with this MMC

            for k = 1 : length(pgonID)
                interP = [interP; pgonID];
            end
        end
        c_interPolySeed{i} = unique(interP);
    end

%     % test
%     for i = 1 : ncvt
%         figure(1); clf 
%         x = vedges(:,[1,4]);
%         y = vedges(:,[2,5]);
%         z = vedges(:,[3,6]);
%         plot3(x',y',z','LineWidth',1, 'Color','k'); hold on;         
%         
%         pid = c_interPolySeed{i};
%         for j = 1:length(pid)
%             verts = c_polyMesh{pid(j)};
%             scatter3( verts(:,1), verts(:,2), verts(:,3), 'filled', 'k'); hold on;
%             scatter3( verts(:,4), verts(:,5), verts(:,6), 'filled', 'k'); hold on;
%             scatter3( verts(:,7), verts(:,8), verts(:,9), 'filled', 'k'); hold on;
%         end        
%         scatter3(seeds(i,1), seeds(i,2),seeds(i,3), 'filled', 'r'); hold on;
%     end
end