title: points on a plane in 3D
body: <p>I'm trying to figure out a way to move objects on a 3D plane that faces the camera using <code>Unity3D</code>. I want these objects to be constrained to the plane, which itself can move about in 3D space (the camera follows it).</p>
  
  <p>To that end, I thought that I'd use the plane's coordinate system to move the objects. I figured that an x,y coordinate on a plane would have a corresponding x,y,z coordinate in actual 3D space. Problem is, I can't figure out how to access, use, or calculate (x,y) coordinates on that plane.</p>
  
  <p>I've done some research, and I've come across vectors and normals and such, but I don't understand how they pertain to my particular problem. If I'm looking in the right place, could you explain how? And if I'm not, can you point me in the right direction? Thanks a lot.</p>