write a plane sweep algorithm in matlab

main.m
function intersectionPoints = planeSweepAlgorithm(points)
    % Sort the points based on x-coordinate
    sortedPoints = sortrows(points, 1);
    
    % Initialize event queue and status structure
    eventQueue = [];
    status = [];
    
    % Loop over the sorted points
    for i = 1:size(sortedPoints, 1)
        point = sortedPoints(i, :);
        
        % If the current point is the left endpoint of a line segment
        if point(3) == 'L'
            % Add the segment to the status structure
            status = [status; point];
            
            % Check for potential intersections with neighbors
            checkIntersections(status, size(status, 1), eventQueue, point(1));
        
        % If the current point is the right endpoint of a line segment
        elseif point(3) == 'R'
            % Remove the segment from the status structure
            status = status(status(:, 4) ~= point(4), :);
            
            % Check for potential intersections between neighbors
            checkIntersections(status, find(status(:, 4) == point(4), 1), eventQueue, point(1));
        
        % If the current point is a vertical sweep line
        elseif point(3) == 'V'
            % Process potential intersection points
            intersectionPoints = processIntersections(status, eventQueue);
        end
    end
end

function checkIntersections(status, lineIndex, eventQueue, x)
    % Check for intersections between the line segment at lineIndex and its neighbors
    if lineIndex > 1
        intersectionPoint = computeIntersection(status(lineIndex, :), status(lineIndex-1, :), x);
        if ~isempty(intersectionPoint)
            eventQueue = [eventQueue; intersectionPoint];
        end
    end
    
    if lineIndex < size(status, 1)
        intersectionPoint = computeIntersection(status(lineIndex, :), status(lineIndex+1, :), x);
        if ~isempty(intersectionPoint)
            eventQueue = [eventQueue; intersectionPoint];
        end
    end
end

function intersectionPoints = processIntersections(status, eventQueue)
    % Process the potential intersection points found in the event queue
    intersectionPoints = [];
    
    % Sort the event queue by y-coordinate
    sortedEvents = sortrows(eventQueue, 2);
    
    % Process each event in the queue
    for i = 1:size(sortedEvents, 1)
        event = sortedEvents(i, :);
        
        % Update the status structure based on the event
        if event(3) == 'I'
            status(event(4), 5) = event(5);
        elseif event(3) == 'E'
            status(event(4), 6) = event(5);
        end
        
        % Find the intersection point
        if ~isempty(status(status(:, 4) == event(4), 6))
            x = event(1);
            y = status(status(:, 4) == event(4), 6);
            intersectionPoints = [intersectionPoints; x, y];
        end
    end
end

function intersectionPoint = computeIntersection(seg1, seg2, x)
    % Compute the intersection point between seg1 and seg2
    % Returns empty if no intersection exists
    
    % Get the y-coordinates of the line segments
    y1 = seg1(2) + (x - seg1(1)) * (seg1(5) - seg1(2)) / (seg1(4) - seg1(1));
    y2 = seg2(2) + (x - seg2(1)) * (seg2(5) - seg2(2)) / (seg2(4) - seg2(1));
    
    % Check if the line segments intersect
    if (seg1(2) <= y2 && y2 <= seg1(5)) || (seg1(5) <= y2 && y2 <= seg1(2))
        if (seg2(2) <= y1 && y1 <= seg2(5)) || (seg2(5) <= y1 && y1 <= seg2(2))
            intersectionPoint = [x, y1, 'I', seg1(4), seg2(4)];
            return;
        end
    end
    
    intersectionPoint = [];
end

% Example usage
points = [
    1, 2, 'L', 1;
    3, 4, 'L', 2;
    2, 3, 'R', 1;
    2, 4, 'V', 0
];
intersectionPoints = planeSweepAlgorithm(points);
disp(intersectionPoints);
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