From 022269a13b10a33131dace614132db825426527a Mon Sep 17 00:00:00 2001
From: Justin Lin <caterpillar@openhome.cc>
Date: Sun, 28 Apr 2019 17:48:41 +0800
Subject: [PATCH] refactor

---
 src/m_rotation.scad | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/src/m_rotation.scad b/src/m_rotation.scad
index 2c01ae2f..48882d45 100644
--- a/src/m_rotation.scad
+++ b/src/m_rotation.scad
@@ -2,12 +2,13 @@ include <__private__/__m_multiply.scad>;
 
 function _q_rotation(a, v) = 
     let(
+        half_a = a / 2,
         axis = v / norm(v),
-        s = sin(a / 2),
+        s = sin(half_a),
         x = s * axis[0],
         y = s * axis[1],
         z = s * axis[2],
-        w = cos(a / 2),
+        w = cos(half_a),
         
         x2 = x + x,
         y2 = y + y,