View Full Version : New Approach to No Flip Knees

05 May 2008, 06:19 PM
I thought I would introduce a new way of making no flip knees and get some feed back. Please let me know what you think, and if you see any problems or ways to expand it to make it better.

Here is a link to the page from my blog:
No Flip Knees (

05 May 2008, 12:21 AM
That's neat! thanks for sharing.

05 May 2008, 06:15 PM
You're welcome, I thought it was a cool find.

05 May 2008, 08:20 PM
Indeed! Use of parenting and rotation to follow the knee control with the use of aim constraint is neat. Actually description was a little hard to follow for me because I was getting lost in what was where. I downloaded the file and it took me few minutes to see what your idea was. Thanks for posting the file.

I am looking for little more though. How about knee control always following the knee to the closest location. There are cases in your method where knee control is away from the knee instead of in the direction where knee is pointing. The simplest idea I had actually creates cycle so it's no use since results are unpredictable. Also i want knee control to move only in limited distance around the knee so it doesnt go far from the knee while animating.

Would be interesting to discuss more about this issue. I hate separate aim control which doesnt follow the target since I always have to animate it and it looks disjointed. For cartoony character its still fine though.

05 May 2008, 09:44 PM
Yeah, the distance from the knee is a bit of a problem. I was able to get better results in that regard using vector math and object matrices, but I couldn't figure out how to get the local global switching to work with it. I didn't spend that much time on it. I think i will go back to it again and see if i can get some better results.

To influence open discussion, I think i was trying to get the vector that is normal to the hip or the plane that is made up by the hip,knee, and ankle. Once that was found i could get the crossProduct of the vector from the Hip Normal and the Vector from hip to knee. Take that vector and add it to the PoleVector object position. Hopefully I'll post a new solution soon. Let me know if you have any ideas!

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05 May 2008, 09:44 PM
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