title: How to rotate a vector around a particular axis
body: <p>The <code>.X3D</code> format has an interesting rotation system. Unlike most formats containing rotation values around the <code>X</code>, <code>Y</code> and <code>Z</code> axis, <code>.X3D</code> gives a normalized direction vector and then gives a value in radians for rotation around that axis.</p>
  
  <p>Example:</p>
  
  <pre><code>The axis to rotate around: 0.000000 0.465391 0.885105 
  Rotation around that axis (in radians): 3.141593
  </code></pre>
  
  <p>I have the conversion from radians to degrees, but I need the rotation values around <code>XYZ</code> from these values.</p>