Cleanup

src/Quaternion.hs

@@ -0,0 +1,13 @@
+module Quaternion
+    where
+import Geometry.Data
+import Geometry.Vector3D
+import qualified Linear.Quaternion as Q
+
+-- apply a rotation as if the z axis moves to the new point.
+rotateToZ :: Point3 -> Point3 -> Point3
+rotateToZ z1
+    | cprod == V3 0 0 0 = id
+    | otherwise = Q.rotate $ Q.axisAngle cprod (angleVV3 z1 (V3 0 0 1))
+  where
+    cprod = crossProd z1 (V3 0 0 1)