Hi,
Im trying to animate a tentacle rig i made. in theory, i thought this would be very simple…make a string of bones, drag around the end bone and set loc and rot keyframes for it. the problem is that it doesnt play back, but simply stays in the last place i put a keyframe. why cant i animate something with auto ik? what can i do? im not interested in using the curve modifier by the way.
blender 2.44 on the intel mac. thx
Auto IK is a convenient solution for occasional and simple IK requirements but since it isn’t a true IK chain, you have to key all the bones in the chain after you’ve moved the end bone (because Blender isn’t going to recalculate it all at animation time since it isn’t true IK).
So, move the end bone then select all bones in the chain and key rotations (you usually key rotations because, except for the root bone, bones in chains are actually located as a result of rotations of each parent bone)
Depending on your needs, you may be better off setting up genuine IK chains.
Which kinda sucks, admittedly, because I’ve seen full-body IK in other programs, and it is a sweet, sweet ride, I’ll tell you that.
One frequently overlooked feature is the Auto-Keying functionality. While I have to admit that it can sometimes be a pain to use (if you’re not careful, you may end up with things moving around that you didn’t intend to move), it does sort out these problems about forgetting to key bones in Auto-IK situations.
To enable auto-keying, there are two ways to do so:
Aligorith
great answers. thanks guys.
Hmmm, I always use Auto Keying with armatures but hadn’t noticed that it solved the Auto IK problem before - but I just checked in 2.43 and it definitely works there so thanks Aligorith for pointing that out.
My coming weeks are about to get much easier I think 
Roboshobo: You still need to understand that this doesn’t give you a full, genuine IK experience. The lack of a target means that if you move parent bones, the tip of the chain will move as if it was still an FK chain. So it’s great for grabbing a hand and sticking it where you want it but not so good if you want to lean on a wall or desk or similar action where the hand stays still while the body moves. …unless Aligorith has some more gems
Remember posting this BlackBoe?:
"I suppose if someone gives you voxel rendering, you’ll find some other massive feature to demand.
CD and Felix, using smilies does not disguise the fact particularly well that saying '“wow, I hope while Jahka was away doing school he thought up more massive features for us, possibly including a large, complex new way of rendering large quantities of complicated participating media materials and numerous other dynamic objects” is a slightly selfish thing to say–and if not selfish, then at least not very grateful–especially because he hasn’t actually finished the first massive feature yet.
Quick note: If I said ‘You suck!’ and then put a smily after it, it’d still be rude, except I’d get away with it because people would be unsure whether I was joking or not."
Slam!!!, Punk!!!
You slam folks around here constantly for being themselves, I only slam the idiots.
Edit.
…
if you don’t wanna post it, P.M. me with it Andy. You’re not gonna piss me off, I actually respect your work and your opinion. Just not the guy who takes every opportunity to kick folks in the groin. The hypocrite deserves no respect. He just posted that crap 2 days ago.
I was trying to fathom your previous post but had missed Blackboe’s contribution (so had assumed it was somehow in response to my previous post?!?!). When I re-read the thread, my question became moot. Anyway, I’m not sure it’s wise to hijack a legitimate and constructive thread with this issue.
…K.