Bullets' velocities and coordinates can be updated. The acceleration due to gravity is calculated. Then the change in velocity is calculated. And then the bullets actually move. Physics is entirely vector based, i.e. x and y components stay separate.
And so the text reflects the changing values for the bullets. There is no OpenFrameworks currently.
I will work on collision detection if my Android app project goes smoothly. Have a nice day!
Merge https://github.com/SpaceShotGame/SpaceBalls
merging my new updates to the master branch