I wanted to determine if a point lay on a line segment and it seemed to be unimplemented, at least in rev31. So I defined a function in class LineSegment2, returning None if there is no intersection. The square root operation is expensive so if anyone can do the same thing using only magnitude_squared, please post it. Here is my code:

def _intersect_point2(self, Q): #Given self.p, self.v, Q.x, Q.y #Intersects iff (p_Q || v) & p between end pts. if self.p == Q: #projection will be 0 return self.p else: diffv = Q - self.p d = diffv.magnitude() s = self.v.magnitude() if (d==0 or s==0): return None ratio = diffv.dot(self.v) / (d*s) #arccos of this gives theta if ratio == 1 and d > 0 and d <= s: #collinear and between return Q else:
return None

To test if a point lay on a segment you could simply test if distance is zero, no?

If so, the whole function could be reduced to:

def _intersect_point2(self, Q): return self.distance(Q) == 0

Or, if instead of True/False you want to return Point/None:

def _intersect_point2(self, Q): return Q if self.distance(Q) > 0.0 else None

Both versions are one-liners, so that's probably the reason why it's not implemented.