Blender: Mixing IK and FK Techniques

[Nalates Urriah]

is this possible? ...I mean with out it being a gigantic pain...

As an example: I want to have a standing avatar sit and then bounce its foot. Moving to a sit it is much easier to use IK to control the feet and legs. Once sitting, trying to use IK to animate a bouncing foot is a pain.

If I lessen the IK influence by shortening the change, it messes up previous frames.

If I turn off IK influence and move to FK techniques, it also messes up all previous frames.

If I turn off IK and use FK to position bones then snap IK to the new pose, it creates movement I don't want when I re-enable IK influence.

I am hoping there is a way to get Blender to record FK LocRot while IK is enabled. That seems to be swiming upstream.

So far the only workable process I have come up with is get the animation pretty much as I want it then go back and select the FK controls and LocRot them in each keygrame. Then I can turn off IK and do the rest of the animation. 

Does anyone know an easy way to switch back and forth and have it work?

 

[Medhue Simoni]

Generally, I try not to switch between the 2, but I can understand why someone would want to. I might have some kind of solution for you tho, but I'm not positive about it, as I haven't actually tried it on purpose. One thing I always do now, is save all the animations that I create in the Action Editor. This makes it easy to store the animations, and to bring them into other projects. Forgive me if I'm wrong, but I thought I noticed that when you save an animation, IK or FK, in the Action Editor, you can then place that animation onto an alternative IK or FK rig. So, you could use IK, save it in the Action Editor, then apply it to an FK rig, and do all you want with it.

[Medhue Simoni]

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Medhue Simoni wrote:

Generally, I try not to switch between the 2, but I can understand why someone would want to. I might have some kind of solution for you tho, but I'm not positive about it, as I haven't actually tried it on purpose. One thing I always do now, is save all the animations that I create in the Action Editor. This makes it easy to store the animations, and to bring them into other projects. Forgive me if I'm wrong, but I thought I noticed that when you save an animation, IK or FK, in the Action Editor, you can then place that animation onto an alternative IK or FK rig. So, you could use IK, save it in the Action Editor, then apply it to an FK rig, and do all you want with it.

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Ok, scratch that. I decided to do some tests. The way I described did not work. I did figure out a way, but it's not just a few clicks, and is somewhat obvious. I created an IK animation, and then saved it as a bvh, and then reimported it. Now, I can just use FK on it and clean it up or whatever. I understand this is not what you are asking, but this is likely how I would do what you want to do. Also, with arms, I would not use IK at all. You can get the same results, or actually better in work time, if you just use Blender's auto IK with the arms.

[Sassy Romano]

You can keyframe the start and stop of IK points.  Hold the mouse pointer over the IK button for the IK handle of interest and "i" to insert a keyframe.

It is a bit mucky when all is said and done.

[Nalates Urriah]

I've found a way to do this... it has been hours of searching and reading. But, I think I have it sorted out now. Once I am sure, I'll post how.

Medhue, thanks for the suggestion. Darien made the same suggestion in Blender-Avastar group. I considered it. But, adding an export-import cycle to my style of trial and error animating seems way less than ideal.

For those REALLY wanting to know what I found right now see: [Animating in 2.5] Getting to grips with Keying Sets. It gives the basics for Keying Sets which seems like my solution. Preliminary tests give me hope it is axactly what I want.

 

[Medhue Simoni]

Thanks Nalates! That was some very interesting information. Yeeehaw, 1 button keyframing. I'm in heaven. Setting the types of keyframing in the auto-keyframing text field is not something I've ever seen in a tutorial, but OMG is it handy.

[Nalates Urriah]

Here is the write up I did from what I figured out.

Blender-AvaStar Animation IK/FK Tip

Keying Sets makes it way easier to shift between IK and FK. Plus, as you said, the one-button-keyframe thing is WAY handy.