Creating a bone setup that would make realistic popup books?

AndyWarby

Hi first time posting here

I'm trying to work out if there is a way i could use bones to create the pop up book technique
So that if the left page opens it creates tension at either side and causes the folded part to pop up

Is this a realistic thing you could do with bones or would the best option be to just animate by hand?

Thanks for any help

Mark Dygert

If it's not all that important to use bones, you could probably do this pretty easily with morph targets?

poopipe

Using morphs will lead to the parts changing size because they only work linearly (unless you use 1 per frame)
This sort of thing can be a complete sod to set up but a simple case  like that should be doable - I'd try something along the lines of a reverse foot lock to start and see what happens. 

kwyjibo

I have done something similar before using morph targets (origami), but this looks like it could be done with simple IK. Parent the IK handle to the bone of the page that opens (green). Rotating that bone then pulls on the joint chain for the popup section. Parent the root bone of the popup section to the other bone.

RN

I tried @kwyjibo's way in Blender, it does work.
For elements that need to open perpendicular to the pages (like in your photos with real paper), you can lay the bones on the pages. I also needed to tick "lock X axis" in the IK settings so those bones would always stay on the pages and not move away from them (the IK solver tries to use all of the 3D space, so you need to restrain it).

Element.L and Element.R form the IK chain:


PS: There's also the pure math way, if you're into that.