ngbinh wrote:

Are there any specific reasons that you use Baraff's method now?

It's considered to be obsolete by timestepping method.

Instaneous method (the last paper we've seen is Baraff's) suffers from alot of problems, including non-existence solution, worst-case exponential,etc...

Saying Baraff work obsolete, when all we do with rigid body dynamics is one way of another based his work, is the equivalent to Baraff saying that Newton second and third laws of physics are obsolete.

Baraff work is the formulation of the equation of Lagragian dynamics for rigid bodies, deducted from Newton first and second laws in a very elegant way.

He provided one method for solving the system of equations one get from such formulation. And all of the work on rigid body physics is based on his 1994 paper.

Implementing a different optimization tecnique to find one of the many posible solutions from the search space does not make his work automatically wrong or obsolete.

I see a great deal of confusion among people starting to study the field of classical mechanic, I believe is generated by many publications of papers that for the most part are fundamentally incorrect. Baraff work does not violate any laws of physics; it is the solution of the system of equations that required those compromises, but the formulation is 100% correct.

Baraff?s 1994 paper is the entire foundation of real-time rigid body physics, I would be more careful claiming that his work is wrong or obsolete, because I think that very few people can contest his work.