title: Keep camera target while moving its position
body: <p>Currently I'm evaluating texture caching and utilize two cameras. Each camera has of course a position, a target and an up vector.</p>
  <p>Camera #1 has a position of [72.1, 77.5, 73] and target [71.5, 77.9, 72.4]. The up vectors is uniform for both [0, 1, 0]</p>
  <p>To see if how well caching is working, I need to spawn the 2nd camera at the same position and translate its position, but also need to adapt the target to still keep looking at the same world coordinate point.
  How can I calculate the target vector using the position translation?</p>