1function line_intersect(x1, y1, x2, y2, x3, y3, x4, y4)
2{
3    var ua, ub, denom = (y4 - y3)*(x2 - x1) - (x4 - x3)*(y2 - y1);
4    if (denom == 0) {
5        return null;
6    }
7    ua = ((x4 - x3)*(y1 - y3) - (y4 - y3)*(x1 - x3))/denom;
8    ub = ((x2 - x1)*(y1 - y3) - (y2 - y1)*(x1 - x3))/denom;
9    return {
10        x: x1 + ua * (x2 - x1),
11        y: y1 + ua * (y2 - y1),
12        seg1: ua >= 0 && ua <= 1,
13        seg2: ub >= 0 && ub <= 1
14    };
15}