# of digits of Pi to look for:
(this changes the mass of the big square below)

Note: Starting at this setting,
visual glitches are apparent.
This happens because there are many
collisions in a small fraction of a second.

Warning! The maximum number of collisions
that can be calculated is ≈100 per second!
At that setting, it will take > !

Animation speed: 

Use anti-aliasing (smooths animation):