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Can you post whatever code you have and give a bit more detail about the effect you want? I like the concept of a “chameleon stuck in time and space” but it isn’t easy to visualise exactly what you mean by that 
Wow, this is an old thread. 
I’d say you have to compute the view direction in world space (not in object space).
Don’t know how to do that in Cg.
And I think a more common name for your concept is “magic lens”.