Gives the intersection point between 2 2d segments, handling all cases

get_intersection.py

def get_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]) #Typo was here
    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))
    p = det(d, xdiff) / div, det(d, ydiff) / div
    def onsegment(seg, p):
        x1,x2=min(seg[0][0], seg[1][0]), max(seg[0][0], seg[1][0])
        y1,y2=min(seg[0][1], seg[1][1]), max(seg[0][1], seg[1][1])
        return x1<=p[0]<=x2 and y1<=p[1]<=y2
    if onsegment(line1, p) and onsegment(line2, p):
        return p
    return None