helixish: bugfix

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/helixish.py b/helixish.py
index 39d525a4e9e19cf8652b49af0f66aff6fe625ee8..afba64e0075ed107a9ab0cd4b93f94930522e268 100644 (file)
--- a/helixish.py
+++ b/helixish.py
@@ -84,7 +84,7 @@ class HelixishCurve():
     # algorithm courtesy of Simon Tatham (`Railway problem',
     # pers.comm. to ijackson@chiark 23.1.2004)
     railway_angleoffset = atan2(*q_plane[0:2])
-    railway_theta =                      tau/4 - railway_angleoffset
+    railway_theta = atan2(*dp_plane[0:2]) - railway_angleoffset
     railway_phi   = atan2(*dq_plane[0:2]) - railway_angleoffset
     railway_cos_theta = cos(railway_theta)
     railway_cos_phi   = cos(railway_phi)