Question on bones axis / realignment.

Howdy! 

Wow! The lessons are definitely more intense now. I'm sure it will come with experience but I feel we can tweak the position of these bones forever. Lol.

I did end up with a couple of questions regarding the bones axis. I can't quite tell why the Z axis is down for the arm and back for the leg. Is that just general practice? Why does it make a difference?

And at the very end I noticed I made a mistake and had subdivided my Thigh incorrectly (and had an extra bone - oops). I ended up dissolving the bones, repositioning, then re-subdividing. Is that the easiest way to approach something like that? Or is there a way to ensure two bones are properly aligned, and of exact same size?

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  • Dwayne Savage(dillenbata3) replied

    It's a matter of preference. I personnally prefer rigify's X down instead of Z down, because I like to key main bending on the X axis. In this case the Z axis is the main bend for the elbow and X is the main bend for the knee. As for the direction, animators tend to favor working with the charater's left and using Flip pose to copy to the other side. By having axis pointing downward(arm)/Backwards(Legs) this makes it positive angles. If you flip it, it will be negative angles. Also when you symmetrize the roll gets flipped. Positive becomes negative and negative becomes positive.  

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  • Dwayne Savage(dillenbata3) replied

    You said dissolved not deleted. If you dissolve(Ctrl+x) the middle bone it will make it 1 large bone again and then you can adjust and redo the subdivide. You can align bones based on the actively selected bone by selecting the bones then select the bone you want all the others to be aligned by last then press Ctrl+Alt+A. As for length, you can enter the length in the n-panel and copy paste to the others. It will only move along the bones Y axis when you adjust the length.

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  • Nathi Tappan(nathitappan) replied

    Wow, there is a lot more do it then! Thanks Dwayne! And also for the hotkey for the alignment, will have to write that one down for sure.

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  • Wayne Dixon replied

    Dwayne is correct here, Nathi.

    The bone roll is mostly preference for this type of thing.  Most often I too prefer to have the main axis for animation to be the X.

    Having the X axis facing down for the arms in this position will mean that the main movement (forward and backward) on the upper arm will be the X axis, and the elbow will also move on the X.  This is in deed much nicer to animate.
    This is usually what I do but it was an oversight when putting this mammoth course together with all its pieces.  It was too late into production when I realised I did this.  

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  • Dwayne Savage(dillenbata3) replied
    Cool Wayne. I just thought you had succumbed to the Maya way. 
  • Nathi Tappan(nathitappan) replied

    Got it! So it is something that is pretty set on stone once we get started then... ? Or could I potentially try and make the change once I have finished following the course as it is?

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  • Dwayne Savage(dillenbata3) replied

    I'd recommend either keeping with it until you finish the course or do 2 parallel version. One that follows the course and one you mess around with so that you can get a better feel and build confidence in your rigging abilities. Keep the one that follows the course in case you run into problems and can use that as a guide to troubleshoot those problems.

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  • Nathi Tappan(nathitappan) replied

    Absolutely! I'll finish following the course first, then make a copy of the rig to test the difference. Thanks Dwayne.

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  • Wayne Dixon replied

    Nathi - it's easy enough to adjust, but you need to understand a few things first.

    The DEF bones can be in different orientations to the CTRL bones, but you need to make sure that the way it is connected isn't causing mode flipping.
    By that I mean if there is a constraint that is set to copy the rotation, when you jump from edit mode into pose mode, those bones are going to reorient and twist the geo with it.
    So either the DEF bones and CTRL bones need to be aligned in edit mode OR the way the DEF bones are set to follow along needs to avoid this potential issue.

    I would suggest, however, that you just follow along first.  Then you can make some notes on how you would adjust things.

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  • Nathi Tappan(nathitappan) replied

    Cool, that makes total sense. Thanks Wayne. And certainly, I'll follow along first. In fact, I plan on taking your animation courses before I return to it... I think I'll make more informed decisions on my rigs once I start animating them and seeing what makes most sense to my brain.

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