Not an easy spacial game. It took me a full pass through before I understood how finite my measurements needed to be.
Parallelogram 2.2 6.1 5.1
Midpoint 3.2 3.6 3.0
Bisect angle 0.6 0.1 0.7
Triangle center 4.0 5.1 5.0
Circle center 2.2 4.1 4.5
Right angle 2.6 1.6 0.5
Convergence 1.0 2.2 2.2
Average error: 2.84 (lower is better)
http://woodgears.ca/eyeball/
Parallelogram 2.2 6.1 5.1
Midpoint 3.2 3.6 3.0
Bisect angle 0.6 0.1 0.7
Triangle center 4.0 5.1 5.0
Circle center 2.2 4.1 4.5
Right angle 2.6 1.6 0.5
Convergence 1.0 2.2 2.2
Average error: 2.84 (lower is better)
http://woodgears.ca/eyeball/