# Bone animation rotation problem

Good afternoon guys,

i have this little animation:

https://gyazo.com/aa8917e8bcbc0988f47d5f1b3a3617b9

I want to make a popup like stairs, i am copying the rotation from the major bone in each little bone and then i am inverting like this (invert,non,invert,non,invert,non)

The problem is that the last bone should remain in the "ground" and the other bones shouldn't go in the z axis more than what they are to be physically correct. But i am having a rough time finding how to...

I tried to limit location but didnt work maybe i did something wrong.

The blend file is here:

https://www.dropbox.com/s/a9tzk4oagqfpenm/PopUpStairs.blend?dl=0

First of you should delete the constraint on every second bone. This will give you a pop up behaviour.

In order to make them not intersect by bending to far, I would simply manually rotate the large bone to the point, where the deformation looks fine. A real popup book would never be able to fully close. Your model also doesn't have proper volume, so cheating is best, as long as it looks good.

Finally, I would suggest adding a root bone. Assign the bottom card to the root bone, and constrain all bones parallel the floor to the root (which will also be parallel to the floor).

This will ensure not only closing downwards, but also closing upwards (if you want that).

In the following I also constrained the large yellow bone to the root.

This is how I would construct the rig.

### Step by step instructions how to create the rig

1. Set up all the bones as they were, add a root bone, which will be used to rotate and move the whole rig.
2. Parent the first bone (red) of the step chain to the horizontal large bone (green).
3. Parent the large green and red bones to the root bone.
4. Make sure all bones' Z-axis are parallel.
5. Lock the X and Y rotation on all bones, except the root bone.
6. Create an additional horizontal bone with the same orientation as the horizontal bones of the steps and parent it to the large green bone. This way we can use less confusing world space copy rotation constraints.
7. Add a Rotation Constraint from the large red bones to the small red bones.
8. Add a Rotation Constraint from the small (inverted) green bone, to the small green bones controling the steps.
9. Hide all small bones.

(Long Gif.)

• Oh man thank you very much! Ive done the first part but the second im having a bad time. I have some problems to chose the correct constraints, and applying the root bone, and the yellow one to the root bone, without destroying the connection between bone and bone 1. Commented Sep 30, 2016 at 19:15
• I only used copy rotation constraints so the red and the yellow have the same orientation. Only the two large bones are constraint with copy location. If you're still having trouble, Ican add a detailed explanation. Commented Sep 30, 2016 at 19:19
• If u may, i would like, please. Or if you dont have time you can send me a link with the solution and i study what u did. But i would like better if you could explain to me . Commented Sep 30, 2016 at 19:27
• I added instructions for a similiar rig. I hope you get all information you need. Commented Sep 30, 2016 at 21:02
• Leander may a ask you another question regarding this problem? I´ve used everything and its working really fine. But now i have a problema that is killing my brain xD Commented Oct 13, 2016 at 12:51