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View Full Version : Newb prob: Axis constraints changing behaviour of IK Solver

digitaldamage
07-12-2006, 05:44 PM
I've searched the forum but haven't come up with much, so here's the question:

I've created a 5-Joint structure for a mechanical object. Joint 1 and Joint 5 are connected via IKrp Solver. At Joint 1, i restricted the part from being moved or rotated in the x and z axis. So for now, Joint 1 is only rotateable in the Y axis.

What i do not understand is, that, on the remaining joints, my IK behaves now differently. Sure, i changed the dregrees of freedom, but shouldn't Joint 2 to 5 behave exactly like before applying the restrictions to joint 1, only limited to such a dregee that they are not moving/rotating in x and z ?
With that restriction enabled, i am now limited in the movement of the remaining 4 joints. Not completely, but partially which is unacceptable. I think i'm having a misconception about how IK works. So any, really any help is appreciated.

One last thing. As you surely have noticed, i'm quite a beginner in Maya and ik as a whole. So please bare with me.

Thanks in advance,
-mat
lemonyfresh
07-12-2006, 06:26 PM
Hopefully I'm not giving you too simple of advice, But you need to tell maya the way that you want IKs to go, you do this by bending them all in the direction you want them to go, left click over the joint and select Set Prefered angle, then create your IK. You may look into the spring IK for multiple joint chains.

Also, you want all of your joints in a chain to have the same rotation axis unless you have some specific reason not to. You can see the rotation axis of joints by going into component mode and then along your middle menu bar at the top of the maya gui is a row of buttons, one is a question mark, toggle this button on and it will display your rotation axis. You can manually rotate these if you want to change the axis your joints spin on.

Good luck, rigging is a bitch.
digitaldamage
07-12-2006, 09:06 PM
Thanks lemonyfresh, but that wasn't able to solve the problem. Maybe i'm totally dense right now...

I attached an image to show what i mean. (I left out one joint on purpose to clear things up) The axis' mentioned in the picture are corresponding to mayas coordinate plane visible in the lower left corner.


http://www.digitaldamage.com/onthemove/joints1.gif

I mean, i feel like an complete idiot. :( I'm 100% sure that there is an awfully simple solution which i simply cannot see. It is probably right in front of my eyes.

Oh well...
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07-12-2006, 09:06 PM
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