Just released v2.0a of ofxMSAPhysics along with a new demo showing off some new features (attractions, collision etc.).
This is a demo for a traer like physics library for C++/openFrameworks. I wrote the lib for a little project with Todd Vanderlin while in Linz, Austria at Ars Electronic 2008 (vimeo.com/1707467). I tried to keep the same API as Traer (so processing code using traer can easily be ported to oF) and it is basically a particle system with springs, attractions, gravity etc (but uses verlet integration instead of RK4).
In this demo I am interacting with the app using the keys:
'p' - add a particle in random position with random mass
's' - add a spring between any two random particles with random stiffness and random rest length
'u' - unlock all fixed particles
'f' - add random forces to all particles
The size of the balls are proportional to their mass
The width of the connectors are proportional to the strength of the spring
Some balls (randomly chosen) are fixed in space. They are red.
more info and source at memo.tv