title: Check if glm::vec3 has be set
body: <p>If I declare a value as <code>glm::vec3 myVector;</code> am I able to just check 
  <strong>safely</strong> that it is null by doing a </p>
  
  <pre><code>if (!myVector) { 
    setVector(myVector); 
  } 
  </code></pre>
  
  <p>or is there a way to set <code>glm::vec3</code> values to null without having to set each individual value to null</p>