I'm working on an animation and I'm trying to build an armature to unfold a chinese food box like this one; to a flat paper page:

enter image description here

Once flat, it should look like this :

enter image description here

But I've got hard times to make the armature work. It's no problem to have the main faces working; but I don't know how to handle the paper "folds" in the corners... I've already tested by assigning manually several times and in different ways the vertexes weights; but I don't get any convincing results.

enter image description here

How would you do / can someone help ? Here's my actual file.

Thanks !

  • $\begingroup$ Unfortunately, the best I've come up with adds two more bones to each of the four corners and requires manually animating at least two of the corners. Have you looked into doing in the opposite direction with an add-on like orgamify or even just doing it with a series of shape keys? $\endgroup$ Sep 29 at 15:17

You have only 1 bone for each corner. Why not use 2 bones so each can control a "face area" as seen in the 2nd reference image?

bones layout
Frame 1 - Areas of influence of the bones

Then add a keyframe for the rotation of the bones at frame 25 and bring them on roughly the same height as the sides of the box. But let it bend a bit because the cardboard material can not compact:

frame 25
Frame 25

Then edit the end frame (50) and fold in the two paper folds as shown in the reference illustration. Try to bring the bones in position by rotating them around the X and Z-axis. Then rotate them around the Y-axis to create the folds and if the mesh intersects or is twisted:

frame 50
Frame 50

Blender will calculate the frames in between, but the animation might not look right. For example, intersections can occur at short notice. So you need to adjust the bone rotation at frame 35 a little bit and get them to a good place:

frame 35
Frame 35

Animation (50 frames):

final animation


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