Thanks all, I'm putting this to bed, as it seems very rare, there are some ways around it, and there are other things demanding attention. I'm still very curious about the *exact* role that the preferred angle plays in the solve, as my previous assumption seems to be incorrect.
Also, just to clarify - I didn't mean to sound like I actually wanted someone from Autodesk to slip me some code - I know it's not gonna happen and is probably illegal...plus, I'm pretty sure it would take me a year to figure out how it worked :P. That being said, I've always thought it'd be nice to have some better documentation on the impact of various inputs to ik the system and their impact on the solve (joint orientation and preferred angles being the main two that seem fairly undocumented). I think I mistakenly replied to Jeremy directly, so I've pasted my original reply below: """ Thanks guys, I'm pretty sure I don't have any cycle errors - but I'll double check. It does somehow seem like the node doesn't fully compute, and it only happens in very specific cases. I'm sorry I can't provide any really good examples - there are good reasons :) I mentioned that setting the preferred angle at <<30,0,0>> wouldn't fix the problem - actually, it would look like it fixed it, then after a bit of scrubbing the problem would reappear. It didn't seem to reappear at <<90,0,0>> degrees, which seems interesting to me, as I was under the impression that setting even the slightest angle would cause the joints to bend in that direction if there weren't any other hints for how to solve. There's a relationship between joint orientation, the preferred angle, and the location of the pole vector that I just don't fully understand. I haven't dealt with the preferred angle much - I've always set up ik on pre-bent joints, and assumed that this angle was somehow set internally, but now it seems like it does have an impact on the way the ik solves in some specific circumstances, even when joints are bent when the ik is set up. """ Anyways, thanks for the help! -- http://groups.google.com/group/python_inside_maya
