View Full Version : Cyclic skeleton

03 March 2010, 10:24 PM
My question is not directly related to characters, but to skeletons so I hope I am in the right place. I searched this forum and the web but I could not find an answer.

I am trying to animate a shaving mirror with a folding mechanic. I am not sure what to call that. I have attached an image of my model. Now I am trying to achieve that I can pull the mirror using an IK handle and have the folding mechanic work properly. I thought I make two bones for each segment, and then make the center joint have 0 degrees of freedom. That way I wanted to connect the center joints of the crossing segments but that would result in a cyclic skeleton, and that does not seem to be possible in Maya. Does anyone have an ideaof how I can model that folding behavior? I want to have one IK handle at the mirror side of the folding that I can pull back and forth. The folding segments should behave as if they were connected in the middle with a bolt. The lower sleeves on both side should be fixed to the polls, and the upper ones should move up and down as necessary to accomodate for the angle of the segments. It's hard to describe, I hope you can imagine :-)

03 March 2010, 01:51 PM
Hi. you can use ikSpringSolver for that situation.
Run "ikSpringSolver" mel-command at first.
Then create bones in necessary places and assign the solver to this joints (use IK Handle Tool and select "ikSpringSolver" in the list).

03 March 2010, 06:49 PM
Have 2 joint chain driven by 2 ikRP solver.. as shown in the image to get the type of movement you ask for.

03 March 2010, 09:03 PM
Thank you for your replies!

@alexanderzagoruyko: I read the documentation of the ikSpringSolver (,topicNumber=d0e313518) but from what I understand, this only makes sure that the angles at each joint are distributed evenly. I do not understand how this will solve my problem of having the two chains depend on each other. Could you please make this more clear?

@shinyprem: This is about how I started off. It allows me to move both chains just fine, but the problem is that it does not preserve the sliding of the uper sleeves, which happens due to the fact that each link of the two chains is connected in the middle with the overlapping link of the other chain.

I have further stumbled upon the multichain solver, which seems to be able to solve for multiple ik handles. What I cannot find, however, is a way to have the two chains influence each other. I have tried to illustrate it better:

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03 March 2010, 09:03 PM
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