first step towards moving to a new mesh/solid/geometry structure

1 files changed, 13 insertions, 5 deletions

diff --git a/transform.py b/transform.py
index 1321c8c..ef8c96c 100644
--- a/transform.py
+++ b/transform.py
@@ -1,16 +1,24 @@
 import numpy as np
 
+def make_rotation_matrix(phi, n):
+    """
+    Make the rotation matrix to rotate points through an angle `phi`
+    counter-clockwise around the axis `n` (when looking towards +infinity).
+
+    Source: Weissten, Eric W. "Rotation Formula." Mathworld.
+    """
+    n = np.asarray(n)/np.linalg.norm(n)
+    
+    return np.cos(phi)*np.identity(3) + (1-np.cos(phi))*np.outer(n,n) + \
+        np.sin(phi)*np.array([[0,n[2],-n[1]],[-n[2],0,n[0]],[n[1],-n[0],0]])
+
 def rotate(x, phi, n):
     """
     Rotate an array of points `x` through an angle phi counter-clockwise
     around the axis `n` (when looking towards +infinity).
-
-    Source: Weisstein, Eric W. "Rotation Formula." Mathworld.
     """
     x = np.asarray(x)
-    n = np.asarray(n)/np.linalg.norm(n)
 
-    r = np.cos(phi)*np.identity(3) + (1-np.cos(phi))*np.outer(n,n) + \
-        np.sin(phi)*np.array([[0,n[2],-n[1]],[-n[2],0,n[0]],[n[1],-n[0],0]])
+    r = make_rotation_matrix(phi, n)
 
     return np.inner(x,r)