home made func

trigo.py

@@ -6,30 +6,35 @@ def angle_to_vector(angle):
     return [math.cos(angle), math.sin(angle)]
 
 
+def get_line_feats(point1, point2):
+    x1,y1 = point1
+    x2,y2 = point2
+
+    a = (y1-y2)/(x1-x2)
+    b = y2 - a * x2
+    return a,b
+
+
+
 def segments_intersection(line1, line2):
-    xdiff = (line1[0][0] - line1[1][0], line2[0][0] - line2[1][0])
-    ydiff = (line1[0][1] - line1[1][1], line2[0][1] - line2[1][1])
+    p1,p2 = line1
+    p3,p4 = line2
 
-    def det(a, b):
-        return a[0] * b[1] - a[1] * b[0]
+    a1,b1 = get_line_feats(p1,p2)
+    a2,b2 = get_line_feats(p3,p4)
 
-    div = det(xdiff, ydiff)
-    if div == 0:
-       return None
+    if a1==a2 :
+        return None # parrallel lines
+    
+    x = (b2-b1)/(a1-a2)
+
+    if min(p1[0], p2[0]) <= x <= max (p1[0], p2[0]) and min(p3[0], p4[0]) <= x <= max (p3[0], p4[0]) :
+        y = a1 * x + b1
+        return x,y
+    else : 
+        return None # intersect is outside segments
 
-    d = (det(*line1), det(*line2))
-    x = det(d, xdiff) / div
-    y = det(d, ydiff) / div
 
-    if (
-        min(line1[0][0],line1[1][0]) <= x <= max(line1[0][0],line1[1][0]) 
-        and min(line2[0][0],line2[1][0]) <= x <= max(line2[0][0],line2[1][0]) 
-        and min(line1[0][1],line1[1][1]) <= y <= max(line1[0][1],line1[1][1])
-        and min(line2[0][1],line2[1][1]) <= y <= max(line2[0][1],line2[1][1])  
-        
-        ):
-        return x, y
-    return x, y
 
 def distance(point1, point2):
     return math.hypot(point1[0] - point2[0], point1[1] - point2[1])