return xoffset, yoffset
+ def get_backface_index(self):
+ # The backfaces have the triangles in the reverse rotational order
+ return 5 - self.index
+
def get_angle_in_plan(self):
"""The angle of a triangle in the hexaflexagon plan."""
return - ((self.index) % 2) * pi / 3.
# angle functions change this one can be left untouched.
return self.get_angle_in_hexagon() - self.get_angle_in_plan()
+ def get_angle_in_backface_relative_to_hexagon(self):
+
+ """"Get the angle of the triangle in the backface relative to the
+ rotation of the same triangle in the hexagon."""
+
+ backface_triangle_index = self.get_backface_index()
+ # group triangles in couples
+ group = (((backface_triangle_index + 1) % 6) // 2)
+ return pi + pi * 2 / 3 * group
+
def get_angle_in_hexagon(self):
"""Get the angle of the triangle in the hexagons.