Hello all, I am trying to do something which should be fairly easy: I am trying to see a circle that let's through an image that is behind it. (As if through a telescope...)
Why not render the picture on a square/rectangle, and put a 'hole' in front of it (for instance a cylinder: make it very wide, thick, and short. rotate 90 degrees so we are looking 'throught' it). moving the picture & your 'hole' in coordinated fashion back and forth could create a telescope like effect, no?