Initial data commit

Task/Find-the-intersection-of-two-lines/Processing-Python-mode/find-the-intersection-of-two-lines.processing-py

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+from __future__ import division
+
+def setup():
+    """ test line_intersect() with visual and textual output """
+    (a, b), (c, d) = (4, 0), (6, 10)  # try (4, 0), (6, 4)
+    (e, f), (g, h) = (0, 3), (10, 7)  # for non intersecting test
+    pt = line_instersect(a, b, c, d, e, f, g, h)
+    scale(9)
+    line(a, b, c, d)
+    line(e, f, g, h)
+    if pt:
+        x, y = pt
+        stroke(255)
+        point(x, y)
+    println(pt)  # prints x, y coordinates or 'None'
+
+def line_instersect(Ax1, Ay1, Ax2, Ay2, Bx1, By1, Bx2, By2):
+    """ returns a (x, y) tuple or None if there is no intersection """
+    d = (By2 - By1) * (Ax2 - Ax1) - (Bx2 - Bx1) * (Ay2 - Ay1)
+    if d:
+        uA = ((Bx2 - Bx1) * (Ay1 - By1) - (By2 - By1) * (Ax1 - Bx1)) / d
+        uB = ((Ax2 - Ax1) * (Ay1 - By1) - (Ay2 - Ay1) * (Ax1 - Bx1)) / d
+    else:
+        return
+    if not(0 <= uA <= 1 and 0 <= uB <= 1):
+        return
+    x = Ax1 + uA * (Ax2 - Ax1)
+    y = Ay1 + uA * (Ay2 - Ay1)
+    return x, y