[ODE] Velocity vs forced based constraints

[Joakim Eriksson]

I was just wondering a bit what the pro/con is of using force based
constraints (as ODE does)
as opposed to using velocity based constraints (as for example FastCar
does)?

With forced based I mean that the constraints that should adjust the
bodies into correct
place is done by applying of a force.
In velocity based you directly change the velocity of the body without
calculating a force.
In my unserstanding the velocity based should be simpler but is it also
more error prone?
FastCar seems to do a very good job of using it and its very fast. Its
also iterative. However
in the free package they only have contact joints but I assume they also
have real joints.

/Joakim E.