bool intersect(GeoPoint a, GeoPoint b, GeoPoint c, GeoPoint d)
{
if (!intersect_1d(a.x, b.x, c.x, d.x) || !intersect_1d(a.y, b.y, c.y, d.y))
{
return(false);
}
line m = new line(a, b);
line n = new line(c, d);
double zn = det(m.a, m.b, n.a, n.b);
if (Math.Abs(zn) < GeoPoint.EPS)
{
return(!(Math.Abs(m.dist(c)) > GeoPoint.EPS || Math.Abs(n.dist(a)) > GeoPoint.EPS));
}
else
{
double xx = -det(m.c, m.b, n.c, n.b) / zn;
double yy = -det(m.a, m.c, n.a, n.c) / zn;
return(betw(a.x, b.x, xx) &&
betw(a.y, b.y, yy) &&
betw(c.x, d.x, xx) &&
betw(c.y, d.y, yy));
}
}
