segment intersections does not work, algorithm tbt

trigo.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+import math
+
+def angle_to_vector(angle):
+    angle=angle*math.pi/180
+    return [math.cos(angle), math.sin(angle)]
+
+
+def segments_intersection(line1, line2):
+    x1,y1 = line1[0]
+    x2,y2 = line1[1]
+    x3,y3 = line2[0]
+    x4,y4 = line2[1]
+
+    xdiff = (x1 - x2, x3 - x4)
+    ydiff = (y1 - y2, y3 - y4)
+
+    def det(a, b):
+        return a[0] * b[1] - a[1] * b[0]
+
+    div = det(xdiff, ydiff)
+    if div == 0:
+       return None
+
+    d = (det(*line1), det(*line2))
+    x = det(d, xdiff) / div
+    y = det(d, ydiff) / div
+
+    if min(x1,x2) <= x <= max(x1,x2) :
+        return x, y
+    return None
+
+def distance(point1, point2):
+    return math.hypot(point1[0] - point2[0], point1[1] - point2[1])