--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Resources/Computations/IntersectSegmentAndHorizontalLine.py	Fri Nov 17 18:01:31 2017 +0100
@@ -0,0 +1,21 @@
+#!/usr/bin/env python
+
+from sympy import *
+
+# Intersection between the 2D line segment (prevX,prevY)-(curX,curY) and the
+# horizontal line "y = y0" using homogeneous coordinates
+
+prevX, prevY, curX, curY, y0 = symbols('prevX prevY curX curY y0')
+
+p1 = Matrix([prevX, prevY, 1])
+p2 = Matrix([curX, curY, 1])
+l1 = p1.cross(p2)
+
+h1 = Matrix([0, y0, 1])
+h2 = Matrix([1, y0, 1])
+l2 = h1.cross(h2)
+
+a = l1.cross(l2)
+
+#pprint(cse(a/a[2], symbols = symbols('a b')))
+pprint(a / a[2])