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IK On to Off to twisted


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I'm just messing around with a character that has a 2001 rig. I'm having him drop in, and jumping up. I started with IK off and keyed the IK to on so he wouldn't go through the floor. But no matter how I try, the legs end up twisted.

 

Any ideas?

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I started with IK off and keyed the IK to on so he wouldn't go through the floor. But no matter how I try, the legs end up twisted.

 

You'll have to be more specific. Having IK off and then keying the IK (the feet? the pose switch?) doesn't make sense. Twisted how?

 

we can't tell. post screencaps. jpgs.

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Well I raised the character up in the air, and turned off IK. I then lowered the character and added a keyframe, and turned on IK. The legs twisted when I did this. I have to recreate this, the program quit on me, and I didn't save it. I turned the IK on and off in the rig set up in the pose sliders.

 

I was trying what I learned on the Jeff Lew DVD. Of course it worked well for him....

 

I don't know if there is a new set up machine for AM? I've been reading about those, but they only seem for the older versions.

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Ok, here is what I'm talking about. I took the rabbit character, and turned the IK leg set up on and off three times. The legs twist up.

 

I would like to know if this is a program glitch, or a sign to either leave IK for the legs on or off when animating. Like I wrote before, I was trying to do some jumps and flips like I saw in the Jeff Lew DVD I bought. So if you're doing jumps, leave IK off and leave it on when you are doing walking and running?

 

Does anyone else have this problem? Finally, does upgrading to V15 solve this? I'm at V13 now.

Picture_1.png

Picture_2.png

Picture_3.png

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AM's constraint system works a bit differently now. The rig is outdated and doesn't work like it use to. And no, v15 doesn't fix this. If you have v12, it may work like it did for Jeff Lew on his DVD.

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Try the exercise with a different character.

 

For example, Shaggy on the 2006 Yeti CD has the "same" rig as Rabbit but his legs don't wander with with each IK ON/OFF change. I just tried it. Something is wrong with the Rabbit model, not with constraints in general.

 

Try the exercise with a different character.

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I've experienced a similar "drifting" issue with a number of characters using the 2001 rig...one of them being an original one I'm building now. What I found was that there was a Translate To constraint in the relationship for that particular pose. In your case, this may be the IK targets in the IK legs pose. The Translate To constraint had an offset built into it that would continue to build each time that particular pose was turned on and off. Eliminating the offset fixed the problem in more cases than one.

 

On the one hand, you get to learn a lot about how rigging and relationships work when dealing with the 2001 rig, on the other, it's a terrible mess trying to actually get any animation done if your rig implodes every time you push a button. I'm glad real life isn't so temperamental!

 

Chris

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Certain constraints need the offset. If you eleminate the offset, the constraint won't work properly.

 

The on/off poses of the 2001 rig are not meant to be turned on/off during animation. They weren't designed to be a switch.

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In other words, either animate with the constraint on or animate with the constraint off? The problem is I need to do both, and because I'm a Mac user The Set Up Machine doesn't work anymore. Or That's what I've been told.

 

Maybe I need to just learn the Squetch Rig.

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Thanks for responding. This is the most hopeful advice yet. How do you eliminate the offset?

 

I tested my theory on the Rabbit model in my library and discovered a couple things. Firstly, I'm not having the same twisting issues that you've encountered. I can turn the IK legs on and off with a slight movement each time. It's not a show-stopper but it will get irritating after about three on/off cycles. Secondly, in searching for an offset in the IK Legs pose, nothing turned up initially that dealt with this. The way I'm going about is by going into the

 

Objects

-Rabbit

-Relationships

-User Property Relationships

 

and browsing to the pose I want to investigate. Inside the pose folder you'll find a list of bones that affected by the pose and drilling down a level deeper you'll see the constraints themselves. I check the offsets for things like Kinematic Constraints to make sure everything matches perfectly, but then this isn't a guarantee to solve every problem. Many times I've found I've had to actually reposition bones or rebuild entire poses from scratch. You can also compare the Rabbit to another model using the 2001 rig that doesn't have these problems and see where they differ. If all else fails, you can try the model from my library and see if that works.

 

Good luck

 

Chris

Rabbit.mdl.zip

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Certain constraints need the offset. If you eleminate the offset, the constraint won't work properly.

 

The on/off poses of the 2001 rig are not meant to be turned on/off during animation. They weren't designed to be a switch.

 

Good point. A team of my students discovered this as well when trying to get a guy to step into a pair of slippers that we'd built into his model. In the end, we simply duplicated the constraints externally in the choreography and animated the enforcement, not the on/off for the pose when he puts them on. Fortunately in later shots he's just wearing his slippers the whole time so nothing fancy needs to happen.

 

Chris

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