From 51caa214d527678dfbe1bb3b6a31609d33110b03 Mon Sep 17 00:00:00 2001
From: Antonio Ospite <ao2@ao2.it>
Date: Thu, 28 Jun 2018 12:42:08 +0200
Subject: [PATCH] trihexaflexagon: clarify the formula in
get_angle_in_plan_relative_to_hexagon()
Write the formula in a clearer way and explain the meaning of the
integer division.
---
src/flexagon/trihexaflexagon.py | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/src/flexagon/trihexaflexagon.py b/src/flexagon/trihexaflexagon.py
index e3aab5c..faf4d90 100755
--- a/src/flexagon/trihexaflexagon.py
+++ b/src/flexagon/trihexaflexagon.py
@@ -44,7 +44,12 @@ class Triangle(object):
def get_angle_in_plan_relative_to_hexagon(self):
""""Get the angle of the triangle in the plan relative to the rotation
of the same triangle in the hexagon."""
- return ((self.index + 5) % 6 // 2) * pi * 2 / 3 - pi / 6
+ # The meaning of the formula regarding the index is the following:
+ # - rotate the indices by 1
+ # - group by 2 (because couples of triangles move together in the
+ # plan)
+ # - multiply the group by a rotation factor
+ return pi + pi / 6 + (((self.index + 1) % 6) // 2) * pi * 2 / 3
def get_angle_in_hexagon(self):
"""Get the angle of the triangle in the hexagons.
--
2.1.4