判断线段相交

Posted 2021-12-24 thusloop

struct point

	double x,y;
;
bool inter(point a, point b, point c, point d)

	if(min(a.x,b.x)>max(c.x,d.x)||min(a.y,b.y)>max(c.y,d.y)||min(c.x,d.x)>max(a.x,b.x)||min(c.y,d.y)>max(a.y,b.y))	
		return 0;
	double h, i, j, k;
	h=(b.x-a.x)*(c.y-a.y)-(b.y-a.y)*(c.x-a.x);
	i=(b.x-a.x)*(d.y-a.y)-(b.y-a.y)*(d.x-a.x);
	j=(d.x-c.x)*(a.y-c.y)-(d.y-c.y)*(a.x-c.x);
	k=(d.x-c.x)*(b.y-c.y)-(d.y-c.y)*(b.x-c.x);
	return h * i <= eps && j * k <= eps;