判断两条直线是否相交

代码

#include

using namespace std;

struct line{
    int xa;
    int ya;
    int xb;
    int yb;


    int getMax_x()
    {
        return xa > xb ? xa : xb;
    }
    int getMin_x()
    {
        return xa < xb ? xb : xa;
    }
    int getMax_y()
    {
        return ya > yb ? ya : yb;
    }
    int getMin_y()
    {
        return ya < yb ? yb : ya;
    }
}line1,line2;

bool is_intersect(line l1,line l2)
{
    //BA(l1.xa-l1.xb,l1.ya-l1.yb)
    //CA(l1.xa-l2.xa,l1.ya-l2.ya)
    //DA(l1.xa-l2.xb,l1.ya-l2.yb)

    //DC(l2.xa-l2.xb,l2.ya-l2.yb)
    //AC(l2.xa-l1.xa,l2.ya-l1.ya)
    //BC(l2.xa-l1.xb,l2.ya-l1.yb)
    if (l1.getMax_x() < l2.getMin_x() || l2.getMax_x() < l1.getMin_x() || l1.getMax_y() < l2.getMin_y() || l2.getMax_y() < l1.getMin_y())
        return false;
    int res1 = (l1.xa - l1.xb) * (l1.ya - l2.ya) - (l1.ya - l1.yb) * (l1.xa - l2.xa);
    int res2 = (l1.xa - l1.xb) * (l1.ya - l2.yb) - (l1.ya - l1.yb) * (l1.xa - l2.xb);

    int res3 = (l2.xa - l2.xb) * (l2.ya - l1.ya) - (l2.ya - l2.yb) * (l2.xa - l1.xa);
    int res4 = (l2.xa - l2.xb) * (l2.ya - l1.yb) - (l2.ya - l2.yb) * (l2.xa - l1.xb);

    if(res1*res2 <= 0 && res3 * res4 <= 0)
        return true;
    else
        return false;
}
int main()
{
    return 0;
}