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}
1// line intercept math by Paul Bourke http://paulbourke.net/geometry/pointlineplane/
2// Determine the intersection point of two line segments
3// Return FALSE if the lines don't intersect
4function intersect(x1, y1, x2, y2, x3, y3, x4, y4) {
5
6 // Check if none of the lines are of length 0
7 if ((x1 === x2 && y1 === y2) || (x3 === x4 && y3 === y4)) {
8 return false
9 }
10
11 denominator = ((y4 - y3) * (x2 - x1) - (x4 - x3) * (y2 - y1))
12
13 // Lines are parallel
14 if (denominator === 0) {
15 return false
16 }
17
18 let ua = ((x4 - x3) * (y1 - y3) - (y4 - y3) * (x1 - x3)) / denominator
19 let ub = ((x2 - x1) * (y1 - y3) - (y2 - y1) * (x1 - x3)) / denominator
20
21 // is the intersection along the segments
22 if (ua < 0 || ua > 1 || ub < 0 || ub > 1) {
23 return false
24 }
25
26 // Return a object with the x and y coordinates of the intersection
27 let x = x1 + ua * (x2 - x1)
28 let y = y1 + ua * (y2 - y1)
29
30 return {x, y}
31}
32