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Twisty segments on the right arm? (11 posts)

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  1. leffler

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    Posted 8 years ago
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    Hi! My first post here, nice forum.

    I´m having big trouble with the twist bones on the right arm. It rotates the oposite direction. It´s the same on the JJ-rig too ...

    The problem must be that the "adwanced twist" needs X to go down the chain. So if you mirror the joints, it wont.

    But if I reorient the joints, I cannot rotate both the left and right chain together with the same value. That is, RotateZ on the left would rotate down, RotateZ on the right side would rotate up

    Is there a solution to this?

    Cheers
    Otto
    http://www.ottoleffler.com

  2. Javier "Goosh" Solsona (admin)

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    Posted 8 years ago
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    What about mirroring only the controllers but not the joints?

    When you connect the controller you need to make sure you negate (with a negative value) the rotations.

    That way you can have a controller that works the way you want and also have the joints underneath working properly

    Hope that helps (it's been a while since I did something like that, but it should work.. I think... )

    Javier

  3. leffler

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    Posted 8 years ago
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    Hi Javier,

    Can´t get that to work either. Only thing that might work is if i put all controllers in a group and set it to -1 in scaleX. But then it will be a nightmare to animate with

    The problem is that the twisting is happening reversed since X is not pointing down the chain ... and I don´t think there so much to do about that if we want that orientation on the joints.

    Is there another way of doing these twistbones? What method do you use Javier? I really like this setup though ...

    // Otto

  4. Javier "Goosh" Solsona (admin)

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    Posted 8 years ago
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    I'll take a look this week at one of my files and let you know.

    I haven't used Maya in a bit, and my brain is very small. The buffer gets filled pretty quickly and it starts dumping things.

  5. leffler

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    Posted 8 years ago
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    Thanks Javier, that would be great. If you want, I can send you an .ma file to show the problem?

    Otto

  6. Javier "Goosh" Solsona (admin)

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    Posted 8 years ago
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    hey Otto

    I just checked quickly

    I'm not using advanced twist. My joints are actually mirrored (and I have Y down the axis)
    I control the twist through nodes (a combination of multiply divides, etc)

    I'm still thinking you should be able to negate the rotation.. get X pointing down the axis (for both twist joints left and right)
    but then control the twist on the right normally, but the left, you might need to do a -1 in the input.. (if that makes sense)

    if you can't get it, I could take a look, but really, I haven't used Maya in a while and I'm a bit rusty.

  7. sim.On

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    Posted 8 years ago
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    @leffler:
    did you orient your Joints ( left and right side ) after mirroring them ? maybe you need to do it for the right arm as well , because the advancedTwist-attributes are just working properly if you have the joints oriented either in XYZ or XZY ( aim-Axis = X ) ... and after "mirroring" they are usually oriented towards -X ( on the "mirrored half of the body" ) ... maybe this causes the twist to happen in the exact opposite direction .

  8. leffler

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    Posted 8 years ago
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    Javier:
    Okey, I´m thinking about giving up the adwanced twist to and do something with nodes, should be pretty cool.

    sim.On:
    I don´t orient the joints on the right side because if I do so I loose the very nice thing for the animator when they can select both arms and rotate in for example Y and both the arms rotate forward. So yes, on the right side I have -X down the chain, that´s the problem

    But I guess I have to check out some other orientations then Thanks for the help

    Otto

  9. dBrooks

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    Posted 8 years ago
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    Essentially what you want is joints that are mirrored behaviourally, with the advanced twist still working.

    Okay, here's a way round it, but I still think issues might come up.

    First build one side of the joint chain, mirror your joints. Orient your controls to this mirrored chain. Then orient the mirrored side. Connect rotation via orient constraint with maintain offset turned on. Failing this, use direct connections and negate rotate X like Javier suggested.

    I've got a hunch this will not be stable.

    I will have a little play soon and get back with the best solution.

  10. leffler

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    Posted 8 years ago
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    Hi dBrooks,

    The problem that I keep getting back to is this:

    If i orient the joints so that X points down the chain on both side, the adwanced twist works.
    But ... then I loose the nice "rotate both arms and they do what you want"-thing :D:)

    So I´ve done a setup with multiplyD-nodes, but there are some flipping issues when going abowe 90degrees. (Which probably wont happen too often in animation, but still ...).
    I think I´m gonna try using aim-constrains next, seen a very nice demo on that.

    But I´m still up for any solutions with the adwanced twist ...

    Otto

  11. dBrooks

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    Posted 8 years ago
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    Okay Otto have a look at this maya file I whipped up for you (Maya 2008 .ma). It's a real simple demonstration of what I explained in my previous post.

    mirrorAdvTwist_dbrooks.ma

    I mirrored the arm joint chain from right to left. I then snapped the orientation of the fk controls to this skeleton. So you have mirrored behaviour in both the controls and the joints. Cool.

    The problem is the advanced twist won't work on the left side with it's mirrored orientation.

    So I reoriented the joints on the left, so that now it will work in conjunction with the advanced twist.

    I then orient constrained the fk controls to the joints with maintain offset turned on. The fk controls on the left side have still got this mirrored behaviour and do what we want. The advanced twist seems to be okay too.

    I'd rather the controls on the left wholly match the orientation of the joints...but from my 2 minutes of playing with the rig it seemed stable enough.

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