matlab多边形区域填充

以下是使用Matlab实现多边形填充的方法：

1. 使用扫描线算法进行多边形填充。该算法通过扫描线与多边形边界的交点来确定填充区域，并根据交点之间的水平间隔对像素进行填充。

function fillPolygon(x, y)
    % 获取多边形的边界点
    boundary = [x(:), y(:)];
    
    % 获取多边形的最小和最大y坐标
    minY = min(boundary(:, 2));
    maxY = max(boundary(:, 2));
    
    % 初始化扫描线
    scanline = minY;
    
    % 初始化活动边表
    activeEdges = [];
    
    % 初始化填充区域
    fillRegion = zeros(maxY, 1);
    
    % 遍历每一条扫描线
    while scanline <= maxY
        % 更新活动边表
        activeEdges = updateActiveEdges(activeEdges, boundary, scanline);
        
        % 对活动边表进行排序
        activeEdges = sortActiveEdges(activeEdges);
        
        % 填充当前扫描线的像素
        fillRegion(scanline) = fillPixels(activeEdges);        
        % 更新扫描线
        scanline = scanline + 1;
    end
    
    % 显示填充结果
    imshow(fillRegion);
end

function activeEdges = updateActiveEdges(activeEdges, boundary, scanline)
    % 移除不再与扫描线相交的边
    activeEdges = activeEdges(activeEdges(:, 4) > scanline, :);
    
    % 添加与扫描线相交的边
    for i = 1:size(boundary, 1)
        % 获取边的起点和终点
        startPoint = boundary(i, :);
        endPoint = boundary(mod(i, size(boundary, 1)) + 1, :);
        
        % 判断边是否与扫描线相交
        if startPoint(2) < scanline && endPoint(2) >= scanline || endPoint(2) < scanline && startPoint(2) >= scanline
            % 计算边与扫描线的交点
            intersectionX = startPoint(1) + (scanline - startPoint(2)) * (endPoint(1) - startPoint(1)) / (endPoint(2) - startPoint(2));
            
            % 计算边的斜率
            slope = (endPoint(1) - startPoint(1)) / (endPoint(2) - startPoint(2));
            
            % 添加边到活动边表
            activeEdges = [activeEdges; startPoint(2), intersectionX, slope, endPoint(2)];
        end
    end
end

function sortedEdges = sortActiveEdges(activeEdges)
    % 按照交点的x坐标对活动边表进行排序
    [~, sortIndex] = sort(activeEdges(:, 2));
    sortedEdges = activeEdges(sortIndex, :);
end

function fillRegion = fillPixels(activeEdges)
    % 初始化填充区域
    fillRegion = zeros(1, size(activeEdges, 1));
    
    % 遍历每一对相邻的边
    for i = 1:2:size(activeEdges, 1)-1
        % 获取边的起点和终点
        startPoint = activeEdges(i, :);
        endPoint = activeEdges(i+1, :);
        
        % 填充边之间的像素
        fillRegion(startPoint(2):endPoint(2)) = 1;
    end
end

2. 使用Matlab的`fill`函数进行多边形填充。该函数可以直接填充多边形区域。

function fillPolygon(x, y)
    % 获取多边形的边界点
    boundary = [x(:), y(:)];
    
    % 填充多边形区域
    fill(boundary(:, 1), boundary(:, 2), 'r');
end