1. Use the 'o' key to let the user toggle between the blue cube and red cube. This lets the user manipulate either object.
2. - Use the 'o' key to let the user toggle between the blue cube, the red cube and the eye to let the user manipulate either object, or the eye. For the eye motion, apply all transformations with respect to ~et (ego motion), and invert the signs of the translations and rotations.