title: Calculate direction vector facing origin
body: <p>I have two vectors defining two separate points in a three-dimensional space. One is static at the origin (0.0f, 0.0f, 0.0f) and the other one will be moving slowly. From this data i need to get a (three-dimensional) direction vector that describes the direction from the moving points current position to the origin. </p>
  
  <p>The moving point will be a directional light (3D game) that always myst face the origin.
  I don't require any code, just basic information on how to calculate the vector.</p>