The parameter space is cyclic, but I limited the target values to stay away from the edges, as to not frustrate the player close to the edge. Originally I had a 1 second cooldown on highlighting the correct position, but I found it to be rather frustrating as you kept going in and out of the target area over and over.
The curve in this case is a simple sine wave around x,y,z with a magnitude and phase shifting over time, z ending up being depth (ie, line width) after rotation.
Thank you for the very detailed feedback! It would be fun to make some kind of shadow puzzle game. hmm.