关于直线与线段

求直线与线段的交点

求交点

定比分点法，用叉积求面积，用面积比代替线段长度比

Point inter_point(Point A,Point B,Point C,Point D)///返回直线AB和线段CD的交点
{
    if(!intersect(A,B,C,D)) return {-INF*1.0,0};///判断直线AB是否与线段CD相交，不相交必须须特判
    double area1=fabs((B-A)*(C-A));
    double area2=fabs((B-A)*(D-A));
    double x=(area1*D.x+area2*C.x)/(area1+area2);
    double y=(area1*D.y+area2*C.y)/(area1+area2);
    return {x,y};
}

判断相交，叉积判断左右拐(跨立实验)

bool intersect(Point A,Point B,Point C,Point D)///判断直线AB是否与线段CD相交
{
    if(((C-A)*(B-A))*((D-A)*(B-A))<eps) return true;
    return false;
}

如果判断线段相交则须用快速排除实验和跨立实验

求线段交点必须先判断相交

时间： 2024-11-02 02:47:15

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