FK Rig with mirrored local axes

[Binster]

Hello!

Having come from a Maya background, I’m wondering if there’s a way of making an FK rig in Blender where the mirrored joints (left arm versus right arm for example) will rotate mirrorwise in local space.

To clarify, if I were to select the left arm and the right arm and rotate both in local Z for example, I would want them to both come together in front, or move apart. In most rigs I’ve seen FK limbs mirror in one axis only (X it seems) but not the other two.

In Maya, I believe you can achieve this by nesting an FK control under a negatively scaled parent empty, but I don’t know if this can be achieved in Blender.

Anyone got any suggestions?

Cheers!

[Piraniac]

So after telling you to go away and post here I’m going to reply anyway

I was wondering about this so had a play around and I think the answer is simply that you just work differently. If your bones are named correctly and using ‘_left/_right’ or ‘.L/.R’ suffixes then you can copy and correctly paste a bones rotation to it’s mirrored counterpart.

So to use your example, rotate either the left or right arm bone forward then ‘Ctrl-C’ and ‘Ctrl-Shift-V’ to copy and paste mirrored. You don’t have to select the opposite bones first which makes it pretty quick. You can copy from multiple bones at once too.

Don’t know how much of that you’ve already discovered, hope it helps! If you like I’m happy to take a look at the rig (assuming you’re happy to give it out obviously).

P

[Binster]

Cheers Piraniac

Yeah, that’s the approach I expect to be using, so it’s no disaster.

Still, though, I’m surprised there’s no way of making joints’ local spaces be ‘mirror sympathetic’ as it were.

If there is a way, someone enlighten me! If there isn’t a way, someone implement it!

[kastoria]

If you are going to manually copy-and-paste the rotation, can’t you just use a “Copy Rotation” constraint with the “invert” options?

[Binster]

Thanks for the reply kastoria!

I’m only considering using copy paste mirror as a last resort really, and then it’s only applicable for animations such as walk cycles where you can take the one quarter time pose and paste the mirror at three quarter time as it were.

I’m still keen to hear if there’s a way to work with local rotations on bones in mirror space.

Even if there is no way to make bones exist in negative space (so their axes are flipped) is there a posing method that allows you to rotate opposing bones in mirrored directions (Like when you use mirror edit)?