利用c++和easyx库实现对一个不规则多边形Weler-Athenton多边形裁剪算法，请给出示例代码

好的，以下是利用C++和easyx库实现Weiler-Athenton多边形裁剪算法的示例代码：

#include <graphics.h>
#include <conio.h>
#include <vector>

// 定义点结构体
struct Point
{
    int x;
    int y;
    Point() {}
    Point(int x, int y) : x(x), y(y) {}
};

// 定义线段结构体
struct Segment
{
    Point start;
    Point end;
    Segment() {}
    Segment(Point start, Point end) : start(start), end(end) {}
};

// 定义多边形结构体
struct Polygon
{
    std::vector<Point> vertices;
    std::vector<Segment> edges;
    Polygon() {}
    Polygon(std::vector<Point> vertices) : vertices(vertices)
    {
        int n = vertices.size();
        for (int i = 0; i < n; i++)
        {
            int j = (i + 1) % n;
            edges.push_back(Segment(vertices[i], vertices[j]));
        }
    }
};

// 定义边界矩形
const int LEFT = 100;
const int TOP = 100;
const int RIGHT = 500;
const int BOTTOM = 400;

// 计算点p是否在边界矩形内
bool inside(Point p)
{
    return p.x >= LEFT && p.x <= RIGHT && p.y >= TOP && p.y <= BOTTOM;
}

// 计算点p和点q的交点
Point intersection(Point p, Point q, int edge)
{
    Point r;
    int x1 = LEFT;
    int y1 = TOP;
    int x2 = RIGHT;
    int y2 = TOP;
    if (edge == 1)
    {
        x1 = RIGHT;
        y1 = TOP;
        x2 = RIGHT;
        y2 = BOTTOM;
    }
    else if (edge == 2)
    {
        x1 = RIGHT;
        y1 = BOTTOM;
        x2 = LEFT;
        y2 = BOTTOM;
    }
    else if (edge == 3)
    {
        x1 = LEFT;
        y1 = BOTTOM;
        x2 = LEFT;
        y2 = TOP;
    }
    if (q.x == p.x) // 垂直线段
    {
        r.x = q.x;
        r.y = y1 + (y2 - y1) * (q.x - x1) / (x2 - x1);
    }
    else // 非垂直线段
    {
        float k = (float)(q.y - p.y) / (q.x - p.x);
        float b = q.y - k * q.x;
        r.y = k * x1 + b;
        r.x = (r.y - b) / k;
    }
    return r;
}

// Weiler-Athenton多边形裁剪算法
Polygon clipPolygon(Polygon subject, Polygon clip)
{
    // 计算多边形交点
    std::vector<Point> intersections;
    for (int i = 0; i < subject.edges.size(); i++)
    {
        Segment s = subject.edges[i];
        for (int j = 0; j < clip.edges.size(); j++)
        {
            Segment c = clip.edges[j];
            Point p = intersection(s.start, s.end, j);
            if (inside(p))
            {
                intersections.push_back(p);
            }
        }
    }
    // 构造交点多边形
    Polygon intersectionPolygon(intersections);
    // 构造裁剪后的多边形
    Polygon output;
    for (int i = 0; i < clip.vertices.size(); i++)
    {
        Point c = clip.vertices[i];
        int k = intersectionPolygon.vertices.size();
        for (int j = 0; j < k; j++)
        {
            Point p1 = intersectionPolygon.vertices[j];
            Point p2 = intersectionPolygon.vertices[(j + 1) % k];
            Segment s(p1, p2);
            if (s.start == c) // Case 1
            {
                if (output.vertices.empty() || output.vertices.back() != c)
                {
                    output.vertices.push_back(c);
                }
                output.vertices.push_back(s.end);
            }
            else if (s.end == c) // Case 2
            {
                if (output.vertices.empty() || output.vertices.back() != c)
                {
                    output.vertices.push_back(c);
                }
                output.vertices.push_back(s.start);
            }
            else if (inside(s.start)) // Case 3
            {
                if (output.vertices.empty() || output.vertices.back() != s.start)
                {
                    output.vertices.push_back(s.start);
                }
            }
            else if (inside(s.end)) // Case 4
            {
                if (output.vertices.empty() || output.vertices.back() != s.end)
                {
                    output.vertices.push_back(s.end);
                }
            }
            else // Case 5
            {
                // do nothing
            }
        }
    }
    return output;
}

int main()
{
    initgraph(640, 480);
    // 定义不规则多边形
    std::vector<Point> subjectVertices = {
        {200, 200},
        {250, 150},
        {300, 200},
        {300, 300},
        {200, 300}
    };
    Polygon subject(subjectVertices);
    // 定义裁剪窗口
    std::vector<Point> clipVertices = {
        {LEFT, TOP},
        {RIGHT, TOP},
        {RIGHT, BOTTOM},
        {LEFT, BOTTOM}
    };
    Polygon clip(clipVertices);
    // 裁剪多边形
    Polygon output = clipPolygon(subject, clip);
    // 绘制不规则多边形
    setcolor(BLUE);
    for (int i = 0; i < subject.vertices.size(); i++)
    {
        int j = (i + 1) % subject.vertices.size();
        line(subject.vertices[i].x, subject.vertices[i].y, subject.vertices[j].x, subject.vertices[j].y);
    }
    // 绘制裁剪窗口
    setcolor(GREEN);
    for (int i = 0; i < clip.vertices.size(); i++)
    {
        int j = (i + 1) % clip.vertices.size();
        line(clip.vertices[i].x, clip.vertices[i].y, clip.vertices[j].x, clip.vertices[j].y);
    }
    // 绘制裁剪后的多边形
    setcolor(RED);
    for (int i = 0; i < output.vertices.size(); i++)
    {
        int j = (i + 1) % output.vertices.size();
        line(output.vertices[i].x, output.vertices[i].y, output.vertices[j].x, output.vertices[j].y);
    }
    getch();
    closegraph();
    return 0;
}

这段代码实现了对一个不规则多边形的Weiler-Athenton多边形裁剪算法，并使用了easyx库进行图形绘制。具体实现过程在代码注释中有详细解释。