I am trying to design a robust cloth system. I have no problem at all simulating things like that using forward integration such as euler, midpoint, runge-kutta, verlet, etc. However, I just can't wrap my head around implicit methods.
I don't understand how you formulate the equations in linear algebra terms. I'd really like to see a VERY simple tutorial, and an actual example of how to construct the equations, and then solve for a very simple system (for example, 3 particles connected by 3 springs).
I looked into David Baraff's Large Steps in Cloth Simulation, and I can kind of follow it, but going from equations to code is a weak spot of mine.
I can use a package like eigen to solve, but I'd also really like to see some code for something like conjugate gradient descent. I don't care about efficiency at the moment, I just want to be able to clearly understand what's going on.