Real-Time Physics Simulation Forum

The Jacobians are simply a and b for the first body (and, of course, -a, and -b for the second body). Is this the result you are getting?

I'm probably not fully considering your problem, but is there a solution where you can temporarily convert the quaternions to a rotation around an axis? (I'm talking about either the 4-component "axis and angle" or the similar 3-component "axis rotation" which is simply the unit ...

Glad I was of some minor help!

I look forward to checking out the implementation (someday, at least - it's not pertinent to my current project but I'd like to fiddle around with it in the near future).

I had tried out Korzen's original demo and also experienced that wiggle exactly once. I couldn't figure out how to reproduce it so I never mentioned it. IIRC, the paper detailed a specific order of solving the constraints ... did you follow that?

Ahh, no problem, I see your point.

Just a tip you could also replace the need for this array altogether by doing something like this in ComputeDarbouxVector function. <snip> const int i = c; const int j = (c+1) % 3; const int k = (c+2) % 3; </snip> Are you trying to make it cleaner or faster? If the performance of that code is criti...

I haven't looked, but it's possible that Jan Bender's PBD code has an implementation, too. But no matter since you've apparently found a solution.

You might note that this section of the forum specifically notes that you don't post Bullet support questions here. Please try another section.

OK, you're (basically) right, ERP is a form of Baumgarte stabilization. My confusion stems from originally using Baumgarte's method on a force-based rather than impulse-based physics system. Perhaps that even has something to do with my difficulty tuning it, but that's water over the dam at this poi...

There is more than one way to fix the inevitable overlap. I don't think Baumgarte stabilization is in favor anymore (I have used it in the past, but it seemed difficult to tune). If you look up the CFM/ERP variables that Erin Catto uses on his impulses, that is one good method (which I am currently ...

Presumably your 'car' needs some downforce, but not generated from aerodynamics like a real car, otherwise you'd probably float off at zero speed. Make sure normal gravity is off (which is a force vector relative to the world), and then apply some sort of replacement force vector always pushing your...

Well, it probably needs to accumulate the impulse for other purposes (limits, warmstarting, constraint breakage, debugging, etc.). But I personally don't know how a PGS solver could work without updated velocities each iteration.

For the subsequent iterations to actually do something useful, I think the velocity has to be updated and stored somewhere . But it's possible that it is not being stored in the rigid body object itself. Are you sure that the velocity isn't being copied somewhere before the first iteration (for exam...

Thanks Mr. Melax for the talk and thanks RBD for the links!

Interesting papers, thanks for the ideas!