function forward_direction
%----------------------1 初始参数设置---------------------------
    l1=50; l2=50; l3=50; %已知信息：臂长
    degree1 = deg2rad(0);%各关节角度
    degree2 = deg2rad(0);
    degree3 = deg2rad(0);
    
    %求出4个点坐标
    bx = l1*sin(degree1); % B点坐标，A为（0，0）
	by = l1*cos(degree1);
	cx = bx+l2*sin(degree1+degree2);% C点坐标
	cy = by+l2*cos(degree1+degree2);
	dx = cx+l3*sin(degree1+degree2+degree3);% D点坐标
	dy = cy+l3*cos(degree1+degree2+degree3);
%-----------------------2初始图像设置---------------------------
    x = linspace(0, 150, 1500);  % X轴范围包含所有分段
    y = zeros(size(x));         % 初始化Y数组
    figure('Position', [0 0 600 600]);
    axe = axes('Position', [0.1 0.3 0.8 0.6]);
    sport_plot = plot(x,y,'.', 'LineWidth', 2);
    update();%计算初始参数点，设置分段函数
    set(sport_plot, 'YData', y);
    axis('equal',[0 200 -150 150]); % 设置坐标轴范围 [x1，x2],[y1,y2]
    title('正向运动学分析'); % 标题
    xlabel('X坐标'); % x轴标签
    ylabel('Y坐标'); % y轴标签
    grid on; % 显示网格
%-------------------------3 更新参数点，设置分段函数----------------
    function [] =update()
        bx = l1*sin(degree1); % B点坐标，A为（0，0）
        by = l1*cos(degree1);
        cx = bx+l2*sin(degree1+degree2);% C点坐标
        cy = by+l2*cos(degree1+degree2);
        dx = cx+l3*sin(degree1+degree2+degree3);% D点坐标
        dy = cy+l3*cos(degree1+degree2+degree3);
        y = zeros(size(x));
        %x = linspace(0, dx, 1500);
        idx1 = (x >= 0 ) & (x <= bx);
        idx2 = (x >= bx) & (x <=cx); 
        idx3 = (x >= cx) & (x <=dx);
        idx4 = x >dx;
        y(idx1) = tan(pi/2-degree1)*x(idx1);         % 注意使用 .^
        y(idx2) = tan(pi/2-degree1-degree2)*(x(idx2)-bx)+by;    % 线性计算
        y(idx3) = tan(pi/2-degree1-degree2-degree3)*(x(idx3)-cx)+cy;
        y(idx4) = 999;
        title(axe, ['末端坐标（x,y）=（', num2str(dx), '，', num2str(dy), '）']);
    end
%--------------------------4 滑块-----------------------------------------
    % 添加degree1滑块
    uicontrol('Style', 'slider', ...
        'Position', [190 110 200 20], ...
        'Min', 0, 'Max', 180, 'Value', degree1, ...
        'Callback', @updatedegree1);
    uicontrol('Style', 'text', ...
        'Position', [140 110 42 15], ...
        'String', 'degree1');
    % 回调函数1
    function updatedegree1(hObj, ~)
        tem = hObj.Value; 
        degree1=deg2rad(hObj.Value);%更新角度
        update();
        set(sport_plot, 'YData', y);
        uicontrol('Style','text','String',num2str(tem),'Position',[400 110 40 15]);
    end

 % 添加degree2滑块
    uicontrol('Style', 'slider', ...
        'Position', [190 60 200 20], ...
        'Min', 0, 'Max', 180, 'Value', degree2, ...
        'Callback', @updatedegree2);
    uicontrol('Style', 'text', ...
        'Position', [140 60 42 15], ...
        'String', 'degree2');
    % 回调函数1
    function updatedegree2(hObj, ~)
        tem = hObj.Value; 
        degree2=deg2rad(hObj.Value);%更新角度
        update();
        set(sport_plot, 'YData', y);
        uicontrol('Style','text','String',num2str(tem),'Position',[400 60 40 15]);
    end

% 添加degree3滑块
    uicontrol('Style', 'slider', ...
        'Position', [190 13 200 20], ...
        'Min', 0, 'Max', 180, 'Value', degree3, ...
        'Callback', @updatedegree3);
    uicontrol('Style', 'text', ...
        'Position', [140 13 42 15], ...
        'String', 'degree3');
    % 回调函数1
    function updatedegree3(hObj, ~)
        tem = hObj.Value; 
        degree3=deg2rad(hObj.Value);%更新角度
        update();
        set(sport_plot, 'YData', y);
        uicontrol('Style','text','String',num2str(tem),'Position',[400 13 40 15]);
    end
%------------------------------5 文本框输入------------------------------
    uicontrol('Style', 'text', ...
        'Position', [450 430 100 20], ...
        'String', 'set 1:');
    uicontrol('Style', 'edit', ...
        'Position', [450 400 100 30], ...
        'String', '0', ...
        'Callback', @setdegree1);

    % 定义回调函数
    function setdegree1(src, ~)
        % 获取输入值
        input_str = get(src, 'String');
        input_num = str2double(input_str);
        % 验证输入
        if isnan(input_num)
            errordlg('请输入有效数字！', '输入错误');
            return;
        end
        % 更新全局变量
        degree1 = deg2rad(input_num);
        update();
        set(sport_plot, 'YData', y);
    end

	uicontrol('Style', 'text', ...
        'Position', [450 370 100 20], ...
        'String', 'set 2:');
	uicontrol('Style', 'edit', ...
        'Position', [450 340 100 30], ...
        'String', '0', ...
        'Callback', @setdegree2);

    % 定义回调函数
    function setdegree2(src, ~)
        % 获取输入值
        input_str = get(src, 'String');
        input_num = str2double(input_str);
        % 验证输入
        if isnan(input_num)
            errordlg('请输入有效数字！', '输入错误');
            return;
        end
        % 更新全局变量
        degree2 = deg2rad(input_num);
        update();
        set(sport_plot, 'YData', y);
    end

	uicontrol('Style', 'text', ...
        'Position', [450 310 100 20], ...
        'String', 'set 3:');
	uicontrol('Style', 'edit', ...
        'Position', [450 280 100 30], ...
        'String', '0', ...
        'Callback', @setdegree3);

    % 定义回调函数
    function setdegree3(src, ~)
        % 获取输入值
        input_str = get(src, 'String');
        input_num = str2double(input_str);
        % 验证输入
        if isnan(input_num)
            errordlg('请输入有效数字！', '输入错误');
            return;
        end
        % 更新全局变量
        degree3 = deg2rad(input_num);
        update();
        set(sport_plot, 'YData', y);
    end

end