Here's an idea... why not just put something underneath the glass.... like a background on the back of a tank? Then all you have to do is find something that looks like tile.
Doh..know why now... refraction would interfere I think. the difference between looking straight at it (the background) vs the side or bottom
Doh..know why now... refraction would interfere I think. the difference between looking straight at it (the background) vs the side or bottom