title: Place one instance of model in ARCore Sceneform
body: <p>Having completed the Sceneform quickstart, I'm still having trouble implementing my model placement method...</p>
  
  <p>Rather than each touch of the screen placing a new instance of the model (as in the quickstart &amp; codelab), I'm trying to have each touch reposition the model to that location while still retaining the drag &amp; scale interation.</p>
  
  <p>Any ideas?</p>